Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Navy - Military - Battleships: => Topic started by: andrewh on August 20, 2008, 01:15:54 pm
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AndyN, Umi and the rest of the Mayhemmers have a lot to answer for!
They helped with such wonderful information while I was building my "cartoon" scale Higgins Hellcat that I was inspired to build a more-scale model of a MTB/PT boat.
AND, while I was competing at the Footy Nationals at Aylesbury (don't ask) my young son and I saw a couple of large Perkasas (one badged as PT109 :-\) and we decided to make (together) something large and FAST. So when we got home I dug out the candidate plans and Angus unhesitatingly selected the 78foot higgins boat by Peter Miller (model Boats free plan just after the roman invasion)
(The candidates, by the way, were Glyn Guest's PT boat, his Miami crash boat, and his Hellcat - all, I think 1/32nd scale)
So, having read the plans and article several times and checked the balsa stocks, off we went:
Photocopied (all-in-one printer) the formers (Peter calls then F1 to F8 - he is, like me a aircraft modeller)
What are they made of? - not on plan or in description, but photos appear to be ply (other builders have used ply and 1/8 balsa)
I aimed to use satsuma ply (recovered from scrap fruit boxes) but that source has dried up at the moment
So I used 3mm ply from the local DIY store - this is thin enough to be cut with a big knife (but I did destroy my cutting mat with the force used!)
Wisdom of hindsight suggests that liteply would be a good material, or satsuma wood, or balsa ply. I would not suggest 1/8 balsa sheet as I think it would be weak and prone to splitting with the grain during the build stresses.
The stack of formers seemed to be a bit heavy - so I added a lot more lightness with a holecutter.
The construction goes on "in the air" with the use of a slotted jig - I found that my table saw produced a slot which was a good tight fit on the former ply, and I glued the formers into the jig with a spot of balsa cement (quick drying and I could easily break or dissolve it out later!)
Keel cut out and fitted - I made the keel and formers to plan, but thought that the keel stuck out too much from the formers, so I notched the keel the make half-and-half joints with the formers and fitted it.
The deck and chine stringers are 1/4 square, but I didn't fancy making the bend at the bow (I could do it but would need the kettle, a waning moon, some ammonia and a virgin to sacrifice) so like other builders I used two laminations of 1/8 x 1/4
The stringers "land" at the bow on solid 1/4 balsa "sub-decks" - they may be visible in the bow pictures labelled S1 and S2. When I cut them out and offered them up there was clearly something missing - of about 1/4 inch thickness. In fact there needs to be a stem plate between them - its in the Peter's pictures asa part, butI can't see it on the plan!
Anyway easily made and fitted, followed by the sub-decks and stringers
I will stop there for now - and anticipate the completion
1/32 nd scale - final length about 36 inches
Power: 500 or 600 type motor - direct drive, 36mm racing prop
cells; 2000MAH 6 or 7 cells buggy pack
Colour scheme: to be determined, but not the single-colour khaki-green. perhaps one of the Zebra/dazzle schemes?
Your feedback, please
Too much/ too little/shut up, andrew/other
andrew
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Yep, I'm in!!. Keep it going Andrew.
Barrie.
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Yep keep it up.
As much detail as you have the time to input is always good. There is always somebody who will use the knowledge.
Thanks for sharing.
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Ooo it's all kicking off now O0
Have a look at http://www.pt-boats.net/ (http://www.pt-boats.net/) - wow!!!! gotta get me one ;D
Keep it coming
The other Andy O0
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Thanks for the responses - I take them as positive, thanks
Time is short today - I work with the US and they have woken up today
Couple of pics - word to follow
Barrie - glad to see you are out there. How goes the Hellcat?
BTW, when I dug out the 540 size motors I found:
A MFA power 15 (flight 540 that used to fly my EMP Silent Knight)
Speed 600 Eco
An Overlander buggy motor - fairly "hot" wind
Two salvaged 540 s from Black and decker screwdrivers (2.4 and 3.6 V labelled)
A carriage drive motor out of a Printer with ribbon cable - has about 365 poles and more torque than a politician
The S600Eco sounds like the favourite on 35mm graupner prop and 6 or 7 nicad buggy pack
andrew
andrew
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So here we are, Formers and keel finally assembled in the jig, stringers stripped from sheet
How do you strip material from sheet?
WhenI embarked on my Thames barge there was a lot of parallel strips required to be cut from 1.5mm styrene sheet, so I made myself a little stripper which scores a line so that a strip can be snapped off. It works also with a no.11 blade in place of the scoring operative point (or Pin as mortals call them)
Takes nearly a second to make so its quicker to make a new one than find the previous version
Pic follows when I take one!
It is now evident (see the pictures of the stringers lightly clamped in place) that I can either glue and clamp the tringers in the slots and have a very wavy boat, or allow the stringers to take a fair line and sdjush several of the formers.
Where is the error? Dunno. I make mistakes for england, but the formers cannot be more that 1/2 mm from the drawing (they stilll have the paper copy pasted to the front side); and they cannot be mis-spaced fore and aft enough to give errors like this.
I could investigate with a ruler and dividers but its an old plan and life is short. (I am certan that the original did not have the problem - this would not be Peter Miller's way and he would have mentioned it)
So I am going for the fair curve, even if the stringers "miss" two of the formers by up to 3mm.
Glued (PVA) the first four 1/8 x 1/4 stringers in place, (not wetted or pre-bent) - left to dry
more later
andrew
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Second stringer lamination added - using white glue and all the clamps possible (clothes pegs)
The side planking of the boat is 1/8 balsa applied with the grain vertical so it was out with the sanding block and sand the "sides" flat for the planking to fit on. When I started it became clear that the bow section had a lot of twist and was too much even for the medium-soft 1/8 balsa I was using, so I covered the last 2 inches of the bow after the rest of the side -planking had dried.
You can't have too many clamps, can you? I buy packs of them occasionally when I see them in "pound" shops. I needed all of them and a few bulldog clamps as well for doing the side planking.
andrew
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Two bits of backtracking.
Before doing the side planking I filled gaps between the formers and stringers in the two places where smooth and beautiful lines required that the stringers missed the slot in the former. These had slivers of balsa inserted and sanded smooth when dry. I also ran a batten over the formers to see if the planking would run smooth, and built up the "shy" formers with balsa strips cyanoed in place.
There, I have confessed to you, I'm not perfect, and my boats contain "adjustments" as required
I mentioned a balsa stripper - here are a couple of pics.
Body is HARD balsa (tea cheast wood) and the fence down the edge is a bit of coffee stirrer or similar hard wood or ply
width of strip is set by measuring from the fence and inserting the no 11 blade or scoring point (pin) through the wood at that place!
Highly technical, innit.
I'm a southpaw so the "in action picture shows it being held against the left edge of a sheet - several light cuts are better than one heavy one (BYKT)
andrew
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The poor mans balsa stripper {-)
Mines a plastic job from SLEC that came with a 4 foot rail and various adjustment pieces
(http://www.modelbatteries.com/catalog/images/5509365.jpg)
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It looks great Andrew! I think it will fly by the time you are done with it. As with your other boats, the lightweight will pay off I'm sure. I like the jig you used, getting the frames straight is critical of course.
I still use the metal yardstick and blade (meter stick I suppose now), long ago I sliced a piece off my thumb doing that, nothing too bad, it grew back, no flat spot even, but have been much more careful since. Tends to yield beveled edges but sure beats ripping them with a saw. The yardstick method doesn't produce constant width either but usually close enough for me.
Joe
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After a slight gap in building things have got under way again :)
Andy - I had one of these strippers, but the size and length meant that I was nevver likely to have it to hand when needed - I also "created" my cheapo stripper when I needed to follow curves when building a Thames sailing barge - so the original design had two map pins to follow the curve instead of a "fence"
Planking of the bottom started and finished - this morning at 06.00
Planks next to the keel were straightforward (garboard strakes). MEMO TO SELF - NEVER plank again with ANY joints like this - I should have run a balsa bearding strip along the side of the keel for the plank edge to land on.
There is a lot of twist, quite a bit of taper in the garboard strakes, and a little taper on the next two planks away from the keel - all the rest are parallel and 3/8 wide. Any wider than this and the twist would become difficult
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04130.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04131.jpg)
The snag of non-fitting formers reared its head - normally I plank onto balsa formers and have no difficulty pinning the planks in good contact. This hull has ply formers and it took a bit of thought to keep it all fair.
I used white glue for all but the two final closer planks - these are actually at the edge, and used PU glue for these - because it sands very well, and there was at least the possibility of some gaps needing to be filled - and PU expands as it cures.
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04133.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04134.jpg)
While I was playing with the PU glue, I put a dollop in a mixing cup - added an equal quantity of water, stirred hard and fast and ladled the pink (this PU cures pink) frothy mess into the forepeak (the triangle at the pointy end) to see it it would expand and fill the space
It did, and before I cut the surplus off I will take a picture or two
So I have bonded the entire bow together, gained a little buoyancy foam and learned something all at the same time
Can't be all bad
Next sanding and deck!
andrew
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Bottom planking finished and sanded - actually one of my favourite jobs
I have not taken the sanding to the final surface, since the lower bow is later made of block balsa, and this will need considerable sanding/persuasion to fair with the bottom planking. Holding the bottom up to the light shows a few thin areas, which I will reinforce on the inside if necessary.
I have decided to finish with dope and tissue (out of doors) not least because I love the smell, and have mumblety years experience dope and tissue covering. It will also be a good base for a car primer spray finish.
I am not decided on the final paint scheme, but I'm seriously tempted by the Zebra stripes! I certainly want someting other than allover grey or (far worse) allover green. Did any Higgins ever get a north atlantic splinter scheme like a flower-class?
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04151.jpg)
Bottom planked and sanded
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04152.jpg)
close-up of my bow filling experiment - the PU foam is pink
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04154.jpg)
bottom view
I had mental and physical trouble with the plan where the planking met the keel. Plan sections show the bottom planks covering the keel towards the stern, but clearly fitting against the side of the keel in the bow half of the boat. I compromised by running the garboard planks so that they fitted the sides of the keel at the bow, and carried on to the stern with a 1/4 inch gap, which I later filled with another plank glued in with PU glue. THIS is why the prop shaft and rudder tube holes are invisible! ;D
Sharpened tubes will recut them thru the final plank
You do collect dead radio aerials don't you? I take them apart and use the tubes (slightly sharpened) to cut holes in soft woods, etc, plastics when heated and my left palm (always)
andrew
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Preview of the bow block as glued (I have already removed a big clamp)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04161.jpg)
To carve this roughly to shape I will use the long blade out of a "snap-off blade" craft knife - usually I have to take it out of the knife to get the angles and access required, but they are SERIOUSLY sharp when new
andrew
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Comin' at Ya
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04156.jpg)
and leaving
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04157.jpg)
There is a 1/4 balsa transom cover to come before deck planking
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04158.jpg)
andrew
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This is a great write-up of a great build. More please!
The other other Andy
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OYEZ; OYEZ!
BE IT HEREBY KNOWN AND DECREED!
You don't have to be christened Andrew to post here (even if it helps)
Andy - thanks for the comment - its not a patch on your magnum opus, but it pleases me and my lad
Brilliant sunshine over the weekend so I did the bow block sanding outside - always more pleasant
The bow area needs another block or two letting in, but is then within reach of filling with Polyfilla
Made the basis of a stand - I use huge sheets of polythene foam and cut them with a breadknife (I know - it looks like it)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04172.jpg)
I may cut a slot in the entire forefoot and insert a 1/32 ply piece - cos this is where the impacts will occur
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04171.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04168.jpg)
I'm pleased with this - I have punched the prop shaft and rudder tube holes through the skin
Transom doubler, Hatch outlines and deck planking next
andrew
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They did have these in splinter camo, see the Hellcat thread.
Another Andy O0
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Hi Andy
Looks good. I started this same boat about two years ago after acquiring the part finished hull. I have yet to complete it (I think I am a bit of a procrastinator). I am enjoying your build and wondering if you are going to scratch build the torpedoes and guns and other fittings.
Regards David
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David,
I, too, plan to take up procrastination, but probably later sometime,
and yes I aim to scratchbuild the guns and torpedoes - In the original plan that is what Pete Russell does and my scrap box is probably similar to his (only younger)
I made a "Cartoon" higgins hellcat and the torpedoes on that were rolled paper tubes with blue foam ends and plasticard fins
How far have you got with yours? Pictures, please ;D
andrew
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Hi Andy
I am at the stage of painting and then assembling the fittings and guns and the like. However I have inherited a problem from the previous owner. The propshaft was put in at an angle for a 380 size motor which would not be enough power for a boat of this size. I have a 540 motor and I am concerned about how the motor and propshaft align. There is no room for the motor to go at a better angle so will have to find a really flexable coupling. I will have to take a couple photos and post them.
Regards David
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David
So the build is well advanced
You would seem to have several motor options - you could fit a 380 size brushless, or a beefy 380 size brushed motor like an AP27 , or you could modify the shaft to gear or belt drive (if you can get a bigger prop in there) or you could remove the offending propshaft.
If its buit as the plan the keel is balsa - I wounder if you can determine what the glue is holding the shaft? It MAY be possible to find a tube which fits down the ourside of the prop shaft tube, sharpen the end till its serrated, chuck it in a cordless drill and attack from the outside - it will be a lot easier that describing it and the existing shaft &tube can be cleaned up and re-used.
And of course you can re-insert it to suit your 1000W brushless outrunner ;D ;D or whatever
Hope this helps and pictures, please, especially of the hatch area
andrew
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Andrew
I altered my hatch (i have two) so that the front of it slides under the front cabin. The rear of the front hatch will be attached with magnets. The second hatch just drops in once the front is in place and it too will be secured with magnets. I will have to take a couple of pics over the weakend.
Regards David
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David
TIA
andrew
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CONFESSION TIME >:(
While fitting bow blocks to tidy up the bow area I peered down the run of the planking, held it up to the light and ran fngers along it (as you do).
Many of the planks are no longer glued to their neighbours, and are free therefore to twist and to run away from the sanding block!
Not a disaster, but a palpable setback!
I planked with a new bottle of PVA glue from a trade counter - it is enormously concentrated, thick and seems to dry hard and brittle. I had added as much water as I could get into the bottle, but the glue was still too viscous. I normally use PVA well diluted so that the water penetrates wood fibres. So I have probably caused this failure by using the glue without diluting it enough.
I am certain that there is nothing wrong with the glue - indeed the quality is just too good for my need with porous woods.
So, how do I recover from here?
There isn't an overall problem - because I will be covering the whole hull with at least tissue and dope, which will bond the whole enchilada together.
However I would like to re-bond the planks before finishing the sanding. Hence the method has to allow me to sand afterwards.
My favourite plan at the moment is to dollop the same pva (better diluted) onto the inside of the hull, and squooge it with a squoogee into the gaps between the planks - they can move enough to allow this to happen.
If I have run strips of insulating tape down the outside to prevent the glue marking the bottom, this should work.
In fact, while there is wet PVA on the inside of the planking I could lay down strips of fleece to bond it all together
Any better advice, please?
MOTOR MOUNT
The plan method is vertical formers with semicircular cutouts for the motor - which is held in place by a metal strap tensioned by self-tappers into some blocks on the base
The base is designed to fit exactly beween two of the bulkheads, more or less level
I will be folllowing this generally, but I prefer rubber bands to hold the motor down (or tywraps) and I like to prevent the motor spinning with some form of rubber friction mount.
So its out to the garage to try the hole saw on some of the same ply as used for the formers. The nearest hole was about 3mm in diameter bigger than a 540 motor - perfect
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC03999.jpg)
a length of silicone fuel tubing slit along one side makes a great packer-and-friction device
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC03998.jpg)
This will work well - I need to make a bit of liteply to fit between the relevant two formers, (I would sit it on a couple of 1/4 square bearers glued to the face of the bulkhead) - I could even just screw it down to the bearers so that it could be changed out for the brushless ratmotor later in life - or the twin zenoahs if AndyN proves persuasive
andrew (unnumbered but genuine)
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I think that I would use an epoxy, does two things for you, first it glues all of the planks back together O0, second it will water proof the inside of the hull O0 O0. You won't need to add and glass cloth, just epoxy will be strong enough. I usually thin the epoxy about a third with denatured alcohol so it penetrates better and I apply it with what we in the states call an "acid brush". They usually have a metal handle and black plastic bristles. And then I toss the little buggers in the trash because they cost me about $.12 each when I buy them by the box, 144 in a box.
Andre :)
Over here in Portland Oregon
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Andre
Thanks for the information - it is one of the things I had considered, but it will need to run between the planks, and then I will have streaks and globs of epoxy on the outside which will be difficult to sand smooth
welcome, too, to the Andrew/Andy/Andre thread!
andrew
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I think your idea of using a low tack masking tape would keep the drips and runs to a minimum.
Andre :)
Over here in Portland Oregon
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Many thanks for the comments and suggestions; I got a little build time over the weekend and investigated the unglued-plank issue more fully.
There are only two bays with planks with unglued edges - roughly the motor location area where the botton is concave and the planks twist a lot.
I have: determined to use diluted PVA, and add horticultural fleece patches to the inside at the same time. I'm not going to use tape on the outside because I need the planks to move during the Squoodging process - I will clean up the outside with a wet cloth while the glue is still wet, and check from time to time to make sure that no more has appeared.
BTW - I don't suggest that what I'm doing is the best or only way, just that I have done it in my mind, and expect that I can follow it thru without drama. There is an aviation saying "Don't let the plane go anywhere your brain hasn't gone 10 seconds earlier"
So progress: Finished the bow blocks - basically cut out any areas which were not solid and bow-shaped and glued in (PU) balsa block, then cut/planed/sanded to shape
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04200.jpg)
After prelim smoothing
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04205.jpg)
And the transom doubler - 1/4 balsa - was PU'ed onto the ply transom, and when dry planed/sanded to the complex radius-reducing-to-nothing shape required
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04202.jpg)
I also found the plans (loud cheers) and bravely cut out the formers in the hatch area, but havn't glued the hatch-forming structure in place cos I need the access for the plank repair operation - for which I need the right trousers (breeks with nothing to lose!)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04204.jpg)
AND I cut out the motor mount plate - from Satsuma ply. It is just resting in place at the moment and the motor sits on a blu-tack mounting bracket just to get an idea of the drive train in place - All looks OK to me at the moment
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04210.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04213.jpg)
Rudder, FWIW, is home-made from bits I have.
Blade is 1mm brass from Proops 1pound box - shaped generally as per plan,
Stock is two nesting brass tubes the outer of which fits the commercial tilller arm
Rudder tube is a length or radio aerial tube (chrome-plated brass which is a good fit on the stock)
Whole shebang soft-soldered together
Prop shaft, etc is Graupner nickel -plated with 4mm thread and 35mm racing prop to begin with
I can see this on the water ;D
andrew
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The rudder stock is two tubes cos one is too thin
(To answer the question in advance)
andrew
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04208.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04212.jpg)
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Rudder assembly - as described before
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04219.jpg)
repair of floating planks by squooging method went very well - no glue penetrated to the outside, but the bottom is now well bonded, and the fleece re-inforcement lays flat(tish)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04215.jpg)
hatch rails now being added:
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04217.jpg)
Deck planks are stripped from sheet - now I just need to make the remaining hatch crossmembers and I can embark on deck planking.
While the lid is off I have the opportumity to get a good coat of white paint inside to help the seeing and cleaning later in its life.
What do you do? Do you bother to coat the insides of boats?
I know that Glyn doesn't - I am thinking more about cleanliness than preservation
andrew
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You could use halfords grey primer inside, providing that you coat every single little bit of boat....
Looks to be coming along nicely, Llanberis next year??? O0
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Andy,
possibly, possibly
Do you think I could slip in two Zenoahs? ;D
Actually I don't do noise, so the rattiest I would go is three brushlesses
andrew
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hi there Andrew
when you have used a soft material such as balsa wood on a hull construction - it is very wise to seal the timber on the inside as well as the outside - although water isn't intentionally wanted on the inside - it sometimes does happen.
An unprotected timber expands rapidly, especially balsa wood. All the joints (you may find) will open up - even the well glued joints. So, as has been suggested, a good few coatings of either Sand'n sealer or Halfords spray will do the trick.
Keep up the good work - it is enjoyable to watch someone enjoying building a model so much O0 .
aye
john
bluebird
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Hi Andrew
Your build is looking really great.
I to am building this and started 2yrs ago !! , you have nearly passed me ;D Its interesting to see how someone else does a build and you are posting some good pictures.
At the moment I am just running the boat as it is and it really lifts on the plane when running at full power, its here that I seem to be having the problem.. I am using an electronize motor with a Viper 15 and 1850 7 cell battery , it lasts for about 15 minutes which seems a bit short to me.
How are you finding the weight as I see you used ply for the formers whereas i have used 1/8th balsa with a double skinned hull and sides, with the 2nd layer being at 45 ish angle, them covered in a very thin layer of tissue paper and dope (Great stuff even outdoors.) and have undercoated with a can of halefords primer .
Inside just coated with some paper and dope again. No leaks yet 8)
Keep up the momentum..
Larry
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Looking good Andy H, no; Andy N, no; Andy G - damn, that's me.
I would coat the insides - but the wood looks so good don't dismiss G4, the resin-varnish pond sealer (sold by garden centres) which is transparent and sets like resin. Because it is.
Laurent, a Belgian modeller sold me on this stuff on year or so back, which has now turned my paper plating into something very like tough plastic. O0
Andy Someone-or-other
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Andrew, It's looking great, the photo of the great pink glob on the bow nearly made me faint, but not to worry. I'll have to learn to use foam some day. I see you used foam for the base too. I'd agree with the others about sealing the balsa, something that penetrates would be good I think. Looking forward to test runs, longbuilds too. Cap
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Cap
You are hereby christened Andycap for the purposes of this thread
The foam you are referring to is prolly the very pink stuff that gets everywhere - thats the color of this particular brand of PU glue. It cures in the presence of water, so before adding the little filler blocks I apply BAS*, just as if i was going to cyano them. This produces a quick cure (about 10 min) and a plethora of pink froth. It cuts off in seconds with a sharp blade and carves and sands pretty much like balsa
BAS is biologically available solvent - I lick them
Thanks everyone for your input on painting inside - I'm going your way.
I will give everything a brush coat of my favourite acrlyic primer and then a coat of satin acrlyic - both water-based. You will all be happy that my balsa is protected and I will be able to see the little widgets that I drop into the hull
larry, thanks for the pics - lovely hull - thats where I'm going ;D
more later
andrew
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Larry,
Been doing a little calculation: If your batttery is really 1850mah (sometimes much more for small loads) and you are getting 15 mins that implies a current draw of 7.4 amps.
I know that Electronize do a 3-pole and 5-pole motor in 540 size, and I remember that Pete Miller changed to the 5-pole version after he emptied the bath! My guess is that you are prolly using the 3-pole version
7.4 amps at say 7 volts is very close to 50watts
This all sounds about right for numbers, but if the duration is too short I'm afraid the only solution is larger batteries (or possibly lower voltage)
The prototype ran, I believe, on a 6 cell buggy pack. This cuts the peak current a lot, and often seems to give very similar performance for a longer time.
I'd love to see your PT boat in flight from the side - I assume she is planing with quite a lot of the bow well clear of the water as, I believe, the originals did.
The weight is pretty good - I cored out all the formers as much as seemed possible and the balsa is medium grade stuff.
Next job is the hatch, and I have a cunning plan ;D
I'm going to have a plank join at the edges of the hatch and seperate the planks there with some polythene sheet - then I will work inwards to the centre line and finish with a closing kingplank. I can be sure tha the hatch will come out when I cut the front and back edges.
I'm also expecting motor changes so the entire motor mount will be held in with screws
BTW - I have a bought(!) brushless outrunner which is rated at 110W at modest Kv - Can't for the life of me see why it shouldn't be rather effective - its about 35gm weight vs 190 or so for a S600!
andrew
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Hi Andrew
I am hopefully going to the pond this weekend if aloud , so will try to get some video of it , at the moment it is planing when fully charged as you say with the bow quite out of the water, but am going to experiment with some new props I have.
was a bit disheartened the other day at a local show when I heard a little lad say "Wow daddy look how quickly that BARGE !! is moving" , well at least he agreed it was moving quickly.
Might not bother with the upper structure and rename it a as stealth torpedo boat. {-)
Larry
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Larry,
Some barge!
I'm sure it is perfect scale for either:
the delivery passage to the fitting out basin
or an actual boat on active service after "The Bridge Incident"
Hope the sail goes well, I would be interested in what props you are using or trying
You could send us a pic of your empty bench and claim the low-vis paint scheme works a treat!
andrew
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Now LOOK what the massed Andys have made me do!
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04221.jpg)
This is after the primer - looks a bit scraggy
BTW - there is a (deliberate) error here - I have run the hatch from Bulkhead to bulkhead, but the plan stops it about an inch short of each end - which strikes me as strange but possibly functional thing to do
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04222.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04224.jpg)
after satin topcoat
and close-up
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04225.jpg)
Deck planking today - I will insert large bits of foam before the deck goes on, and probably the motor mount base plate - since it runs most of the way acrosss the bottom, and may not be east once the deck is on
andrew
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Hi Andrew how is your Higgins getting along ?
Took mine it out for a run , using a bog basic carbon 40mm prop, as the video shows it is lifting nicely at the bow however I am not sure if this should be higher ?. Unfortunately the pond was full of leaves & twigs which kept snagging the prop , the engine even after this short 40 second run became quite hot to the point that it actually was seizing until it cooled down, so was thinking of adding a couple of Graupner large water cooling inlets and a carbon Hydropropeller 42mm next time.
http://www.youtube.com/watch?v=ncKI2CQLUsU
Look forward to seeing yours in the water.
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Larry,
Thanks for the video - havn't been able to access it yet - Utube wants me to log in and I don't.
Fron a distance, and in large ignorance, it seems to me that the prop may be larger than the motor and its cooling likes. Adding cooling coils will certainly improve matters.
But I can be ABSOLUTELY certain that increasing the prop will accelerate the overheating, but the ride might be exilarating while it goes.
I am not at all a boatie, but my habit while flying would be to reduce the prop size till performance drops off then increase gently till you can live with the duration - this will give the coolest motor for a given speed, and will be quite sure that the motor is spinning as fast as possible - thus giving the highest eficiency.
I did have a re-look at the original article and found that Pete M finished up with 7 cells and an Electronize 3-pole motor, but not the hottest one, so probably the 7 amps I estimated for your boat was much the same as his. If that is what you are using the motor should be reasonably happy and cool (altho stalling on weed or sticks could lead to a huge overheat - if the ESC permitted the current to flow)
At my rate of build I would expect to overtake you perhaps tomorrow ;D ;D
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04234.jpg)
starting planking- orange is polthene bag to allow the hatch to release
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04235.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04238.jpg)
andrew
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Not sure you have enough pins there. {-)
Ps Ducks were not impressed either when i went a bit to close by accident , glad there was nothing on the deck as he used it as the takeoff platform..
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You ain't seen nothing yet - That pic was taken about 2am and shortly theafter I borrowed a load more pins and completed the planking
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04241.jpg)
The gap in the centre of the hatch was not really planned - I just could not get my hands into the forest of pins ;D
It came in very useful in removing the hatch for the first time - I could pull upwards with a wire hook poked in thru the gap. It all went well and the hatch separated sweetly.
The next stages (sanding, doping) I aim to illustrate using the new mayhem facility which is a bit like Photobucket, but involves delivering dust and smell to your computer (Dustbucket and Dopebucket0 If you do not have an account with Dopebucket you can read the post while spraying yourself with the wife's hairspray.
Why are you looking at me like THAT
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04240.jpg)
The fretful porpentine!
andrew
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I always think it's a shame to cover things like that up! However, in the interests of safety and accuracy, you've made the right decision: looking forward to more.
Andy #1963
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How are you protecting the other side of the deck planking?
Andy #1964
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Andy - any and all Andys!
Other side of the planking? - forgive me - I must be slow today. Not sure what you mean.
Larry - video works. Nice high-speed barge! Have you also got an IC engine in there? The noise level - imho suggests something catching, interfering or otherwise not aligned so as to be completely smooth.
Progress so far - deck planking lghtly planed and rough sanded - (the hatch in this pic is slightly raised - intentionally)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/Plankeddeckoct1.jpg)
And the hatch comes off!
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/Plankeddeckoct3.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/Plankeddeckoct4.jpg)
andrew
All the hull needs finish sanding, 3 coats of dope then heavyweight tissue applied wet with thinners
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Non-sequitur!
Before decking, I cut some foam to filll the bow compartment - polyethylene foam FWIW, same as I used for the stand - we get huge sheets with some purchased components
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04232.jpg)
the foam is just visible filling the compartment behind the forepeak
andrew#00000001
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What he was talking about is the under side of the decking, the inside of the hull. I usually paint the under side of my deck planks before gluing them down.
Andre, Andy 1959
over yonder in Portland Oregon
PS I take the Andy from my last name Anderson {-) O0 {-)
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Non-sequitur #2 - triggered by Andre
I watched the Scots Guards trooping their colour (mid 70s?) , with their colonel at the head - he was (and still is) Gregor MacGregor of MacGregor, who was also THE MacGregor (of that ilk).
I mentioned this in Liege to a flying friend (as you do) and got the reply: "Yes, I know him - went to his wedding in Invararray!"
small world, not many names!
i don't usually seal any wood inside a boat - I generally incline with Glyn Guest and let things drain and dry with the hatches open.
Howsomever you lot of Andrews, andres and andys have persuaded me to dollop the inside - so I will have a go at the inside of the deck with my U-shaped brush for brushing round corners. Actually I will probably hold a lump of foam in my fingers and sloosh the stuff in place!
The hatch is easily coated - but I have a little re-inforcing to do first round the edges
Thanks for the explanation - I'm a little errrrrr; errrrrr; slow on the uptake
andrew
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Hi Andrew
Sorry it has taken so long to post a photo. I used the film cases as my machine gun tubs. I also had the hull fiber glassed at a fibre glass factory.
Regards David
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David - Looks very nice!
What motor, prop, please? and have you had her in the water?
Speaking of which - this happpened over the weekend:
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04259.jpg)
and also this
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04258.jpg)
So I reckon I'm catching you-all quite fast :D
These pics are after 3 coats of nearly neat dope - good enough to be waterproof, especially with blue-tack in the propshaft hole
Funny thing making models - or indeed anything - I put about the same time in every day - about 20 to 30 mins, but sometimes there is a lot of progress, and sometimes you move what seems like a long way! It must be quantum, or something
I have realised that the original and all the replicas I have seen do not have the characteristic Higgins bronze exhaust pipes - these will be added when I find a good enough side view or drawing to be able to space them properly.
Now the doping on of the tissue - this is venerable heavyweight model tissue - applied wet (damp) and applied with thinners in the time-honoured way - it went on very well, with (near-) perfect smooth surface, and reasonable edges. I used one peice for the deck and hull bottom (slit along the keel for 1/3rd of the way back from the bow)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04261.jpg)
and this is the hull this morning getting its 3rd coat of dope
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04263.jpg)
pardon the mess - I took her into the garage to dope at about 6.15 this morning - the lovely odour should have reduced enough to bring her into the house by this evening
andrew
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Andrew
" I have realized that the original and all the replicas I have seen do not have the characteristic Higgins bronze exhaust pipes - these will be added when I find a good enough side view or drawing to be able to space them properly."
Is this what you mean? :-))
By the way you might want to explore this site "Save the PT Boat" ( http://www.savetheptboatinc.com/ ) it is a site where a group of PT Boat Veterans here in Portland Oregon are restoring a Higgins PT Boat. I am sorry it took so long for me to put 2 and 2 together and get 4, :embarrassed: and realize that you were building a model of one of the Higgins boats and there was a great source of photos and information right here in Portland.
Andre (Andy 1959)
over yonder in Portland Oregon
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Hi Andrew
She has yet to undergo sea trials. I am going to use a Johnson 540 motor (I have 10 of them) and a 35mm three blade prop. I want to use a SLA battery as my brother is in the battery business. I have one of those EL ESC's that you get off Ebay (it was cheep, cheap) it is rated at 110amps and I think the motor might just scrape under that {-) {-). What I do have a problem with is the angle of the propshaft. I can not take it out as it has all been fibreglassed in and would be too hard (for me) to put in another tube at a different angle. What I would like to do is use a belt drive from the motor to the shaft (less noise than gears). That would give me room to put the larger motor on a proper mount. I recall someone on the forum who uses belt drives on their models but can not find the post. If anyone has any ideas of belt drives and advice it would be most appreciated.
Regards David
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Andre,
Thanks for the link to the PT boat site - I was a little aware of it as Umi has posted us one of her videos of that boat in action (on the Hellcat thread). So you are up in Portland, too - its an area I have always wanted to visit - I come from the West Coast of Scotland so sea, forests and weather are all familair.
Thanks too for the pic - this is one of the pics that I was going to take the dimensions off.
It really is a goldmine because it shows the size and location of the exhausts, and the "chocks" ahead of them, and the way the spray chine rail stops at the rear exhaust (it also doesn't run quite to the bow)
David
I think you might squeeze in under 110Amps {-)
Will a gel cell survive the current draw? I don't know which winding of motor you have, but it could take up to 30 Amps! This would distress a gel cell, I think.
Removal of a prop shaft is not totally impossible - even if epoxied in. Let me know if you really want it out. i assume that it is at too great an angle so the prop is very low and the motor very high?
belt drive is a good idea - suggest that you find a suitable belt (they are sold by the model boat traders over here - and also used by all MFA olympus drives.
I will do a sketch when time permits - but basically you epoxy an aluminium (or ply or glassfiber PCB) plate to the existing propshaft tube with a good strong fillet for support. You need a hole for the motor bearing housing and slots for the motor fixing screws (so you can adjust the belt tension) Probably a speed ratio of between 2:1 and 3:1 seems good with a bigger propellor to suit (Glyn Guest suggests starting at about 45mm diameter with 2:1 ratio)
Sketch and URLs follow
andrew
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An SLA battery will most definately not take the current draw.
I had a 12v 5ah SLA in the club Perkasa, which got way too hot for comfort (SLA batteries shouldn't even get warm)
You would probably be best off going to component shop and getting one of their Ni-Mh's, I've now got one in the perkasa that lasted plenty long enough but nearly burnt the motors out. Nice plume of smoke coming out of them after about 20 mins...
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David,
Forgive the Janet-and-john sketch, please, but this would fit a belt drive to existing boat with prop shaft
(http://i222.photobucket.com/albums/dd159/andrewh_photo/beltdrivesketchJ.jpg)
Whatever you do please add good bracing so that the motor/drive assembly can't flap around :D
andrew - just one session from the water
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Hi Andrew
Thanks for the sketch, I will go down that path. However I will have to have the motor around the other way. Sort of in line with the propshaft as apposed to over it, as I would not have any room for the battery.
Thanks again.
Regards David
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Great, David, but even more need for the bracing to avoid destructive flapping :D
I use a lot of foam Polyethylene and polyproplyene salvaged from computer and similar packing - usually I use it as motor mounts by just cutting a trough of the same diameter as the motor case (using a dead motor case as a cutter) then rubber-banding (or tie-wrapping) the motor down to the block of foam and hot-melt-gluing the whole assembly in place
(I may yet do this on the PT boat - with motor cooling slots or watercooled coils )
andrew
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David
The belts I was thinking of were:
http://quantrum.co.uk/redbankmodels/olympus-belt-drive-p-1363.html
http://www.mfacomodrills.com/timing_belts_timing_pulleys/timing.html
Admittedly all these are UK based - There used to be a 2:1 Graupner unit called the Speedgear - don't know if it still exists.
My scrap box has several suitable belts and pulleys salvaged from dead printers, etc
andrew
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Hi Andrew
The Olympus looks ideal. I have bought a lot of stuff from Redbank in the past so no worries there. I do have a few questions though. Is it a motor mount or do you have to mount the whole thing onto a mount and then the boat. Does the threaded shaft have to be attached to the prop shaft via an in-line universal joint. Sorry about all the questions but I have found some new enthusiasm.
Regards David
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David,
From the top:
It was designed for IC engine replacement so it has flanges for beam mounting - not easily visible in the pic
so you might need to arrange something to give support at the right angle
I have an idea about how this might be atrranged - again easier to sketch than describe
I think its an M6 thread, I seem to remember so you would need an M6 or maybe plain 6mm end for a universal joint
Have you got a pic off your boat wit the hatch off - showiiing how far the prop shaft comes, and at what angle?
andrew
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Would one of these suffice, or three of them for scale...
http://robotbirds.com/catalog/product_info.php?cPath=56_102&products_id=961 (http://robotbirds.com/catalog/product_info.php?cPath=56_102&products_id=961)
You may have figured by now I quite like robotbirds...
Andy 1964 :-))
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Andy,
They would look to be ideal {-), but I can see an 11x7 prop might be a challenge and where would we put the touchpaper?
3 times 150 watts is er; a lot of watts.
I had done a little figuring, and have a 15A bell motor, so with say 10V thats 150Watts (and good efficiency) and light weight whereas the S600 might be 10A at 7V = 70 watts with no more than moderate effiiciency.
And I have a spare channel and can reverse it with just a changeover switch on two of the phase wires. I have been mentally working out an electrical interlock so that I can't reverse unless the throttle is closed
And two bell motors or other cheap 15A brushlesses would be great - altho the structure would have to be modified to get appriopriate access.
andrew
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Disaster narrowly averted!
Had a short session last night - epoxied the propshaft, rudder bearing tube into the hull and assembled the motor mount from ply parts. Opened a new pack of epoxy - using my favourite fast epoxy - its called 151 and comes from a pound shop for guess how much.
It has always been reliable, hardens to a rock-hard state and takes 20 to 30 minutes at room temperature to set (Much, much less if I put the component on a light bulb or mosquito-killing heater :D)
Last night the new pack (twin tube dispenser) didn't want to dispense the brown component (it seems to crystallise in the tube nozzle) but I got a fairly even amount of both bits, mixed it very well (starbucks stirrer), added a little microbaloons for gap-filling and did the job.
3 or 4 hours later it had not started to set , or even gell, so I prepared to worry, but left it overnight, and this morning it seems to be OK.
I will give all the bonded parts a very good heat cure as well, to be quite sure (in fact I don't like the bare propshaft stickin' out of the bottom of the hull, so I will fair it with a 1/4 balsa strake and will have to mix another batch to do this and will cook both of them in one go (fan heater aimed carefully).
I believe that support for the prop shaft is important - I am quite capable of putting the boat down unwisely, and hitting an obstruction at speed would certainly try to bend the prop shaft if it was unsupported
Has anyone else faired the prop shaft, or have you left it bare?
andrew
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I like a support for the tail end of the prop shaft, usually a triangular fillet on a planning hull.
-
Heres the support on my I.C Huntsman, 1/32nd brass.
None of my other boats have one, even my big Zenoah catamaran has about six inches of exposed Flexi, so i dont think it'll be too much of a problem.
Andy 1964 :-))
(http://i288.photobucket.com/albums/ll184/andyn_01/DSCN3372.jpg)
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Thanks for the replies, I would always aim to have lots of support for the propshaft, and have given it a triangular fill-in fairing, altho I could have made up a brass stern-bracket, maybe silver soldered
Sorry about the quality of the photos - I suspect that the camera is in macro mode (but can't easily check since the screen on the back is broken)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04299.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04298.jpg)
I see that the rudder tube is rather less than vertical :((
I have screwed in a floor made from satsuma ply and mounted the rudder servo poking through it with a rather awkward angle on the linkage
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04297.jpg)
BTW the t'other box on the end of the servo lead is my servo tester - one of the best 6 quid 50p I have ever spent
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04296.jpg)
On the water this week?
andrew
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What are you going to power it with batteries wise, and what motor have you settled on?
Those robotbirds motors would have been ok, the Tethered Hydro guys use airscrews that are cut down and balanced ok2
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It's looking great Andrew. I will be interested to see the motor and battery set up too, I'm sure you have it well figured. I would have thought you'd replaced your camera by now, but I imagine you can get a pretty dandy motor and battery for the price of a camera. You will need a new camera to take the movie though right? Looking forward to seeing it under power. Cap (or Andycap as you say)
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Thanks for the comments.
I am on a deep economy setting now and for the foreseeble future so all the gear will be what I have, or can make
This makes Andy's question simpler to answer :}
No new camera, too, for the same reasons!
Motor will be either a Hummingbird 15, a very soft flight motor from the dawn of time, a Speed600 Eco, or a bell motor (brushless); batteries will be initially a 6cell 2100mah buggy pack, possibly an 8-cell sanyo2000 flight pack or a load of Li-ions (2S:3P?) reclaimed out of computer batteries.
Invidentally I notice that at work our drills run on 35V, 1.3AH packs (hundreds of them!) on investigation they are Li-ion, obviously 10S, 1P, and each cell is clearly able to handle reasonable amps - If I could reconfigure one as 3S;2P I reckon i would be on a winner, except that they don't belong to me :((
Motor mount tonight, possibly followed by trials :} :}.
before painting I will fit the spray rails, exhausts rubbing strakes and probably the toe rails as well
Does anyone have a good way to make toe rails?
I am thinking of making two together, out of 1/16 styrene, by drilling holes for the rounded inner shape, cutting out a slot to join the holes - then slice into 2 parts for finished rails
andrew
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Hi Andrew
I made my toe rails by cutting lollipop sticks in half length ways and using my dremal scalloped out the holes, after sanding them to size. It does not look perfect but it was the only way I could think of how to make them.
Regards David
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David, thanks, thats a very workable solution. I use lollipop sticks and stirrers a lot for strip wood and packers.
How do you get them to follow the curve of the deck edge? That's the reason I was thinking of styrene.
Got the motor mount ready for installation this morning - it will also (initially) be screwed down.
While playing with the motor/coupling/shaft i noticed the reason that I originally "retired" the Hummingbird motor - it suffered a bent shaft in one of my "tent-peg" landings.
So the S600 eco it will have to be - I will equip it with supression and flying leads
I also noticed that the local boat shop have sold me the wrong coupling end for the shaft I am using (which I bought at the same time) its probably usable but not good.
andrew
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Andrew
What I did was cut the stick into three once scalloped and then glue into position following the curve. I filled the joins with CA and micro sawdust from the sanding. I know it is not completely curved but I think it looks OK after all trees are not curved {-) {-) {-). I also used these sticks for making the radar mast, they are very handy things. I am unsure of the type of motor you are using (it must be for Aircraft) It is a bit of a pain when you get home from the hobby shop itching to go and they have given you the wrong bits.
Regards
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Andrew
What you do with your Popsicle sticks is soak them in hot water or water with ammonia in it (till is easily bendable, it may take a half hour or so) and then bend them on a form that is close to the curve that you need and secure them to the form and let dry, once dry they will hold their shape and you can glue them in place. I also drill a small hole all the way through the toe rail and insert a piece of wire through them into the deck to pin them in place. Once you fill the hole for the pin, sand and paint you will never know the pin is there but it will make the toe rail much stronger. I would pin all of the details that are going on the deck just for strength.
Andre :-))
over yonder in Portland Oregon
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Thanks for the popsicle hints, Andre, I use them for lots of constructional uses as well as glue mixing, etc.
:}WELL :}
Trial run today!
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04323.jpg)
Motor in place
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04325.jpg)
Floating in running trim
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04332.jpg)
She runs :} :}
instant assessment - Staggeringly noisy, motor, ESC and battery cool after 20 mins running, scale-looking and very safe (and Dull)
more in a minute
andrew
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I have under-propped the motor (35 mm) and the S600 is a huge beast, I think I will try a little 540 buggy motor I have - much lighter and hotter
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04340.jpg)
Not easy to take pics with one hand
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04336.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/th_MOV04341.jpg) (http://s222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/?action=view¤t=MOV04341.flv)
See whaT i MEAN ABOUT THE NOISE!
andrew
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Looking good.. :-))
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Looking great :-)) O0 :-)) O0, about the noise I don't know I didn't hear a thing (no speakers on the computer %) ;)).
Andre
over yonder in Portland Oregon
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Could it be noisier because the hull is empty at the moment?
ken
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That noise is the drive system vibrating, could do with an oiler on the shaft and some grease in the coupling.
-
Thanks for your noise observations - I'm sure that they are all true
I will trace and fix the worst of the noise before long - probably when the boat is hauled ashore for painting.
A few more observations from the first test (6cell nicad pack):
- Boat very "dry"
Prop appears to be cavitating at all speeds above half throttle
Prop CERTAINLY cavitating when the rudder is put over - even a small amount
Safe to use full throttle and rudder at the same time
Goes astern, but steering not wonderful.
Radio range pathetic! Some idiot had not connected the Rx aerial, not taken any wire to the test area. I had to poke the 3inch stub of the aerial vertically up thru the hatch and this gave me about 35 yards
Balance appeared fine
Bow wave thrown out "sideways" like a pair of wings
Not exciting :((
HOWEVER
This morning at dawn I slipped in a 7cell pack of 2000SCs and gave her another test run:
Fast , not entirely safe handling
wet - water splashing over the deck
Turning, even a little at full speed led to digging in the inside chine, the bow dipping and getting very wet
(I will fit the spray rails next!)
Motor, ESC and batteries still very cool after 20 min running - I am still radically underpropped
The pack is very heavy - also the motor so the boat weight is considerable - I'm sure the right answer is 2S Lipos and a lighter motor
So this is the way to go: and if a little is good, more is better and too much is just enough :} - I will try 8 cells and see what happens!
Another trial, weather permitting, at dawn tomorrow
andrew o/c PT boat
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Would it be an insane suggestion to move the batteries depending on the motor speed? That is: all stop - waterline perfect. Full speed - batteries head transomwards?
Andy #1963#
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Andy - thats direct thinking! It seems that Higginses more or less do this automatically - they lift the bows as the throttle increases.
This one - probably because of the absence of spray rails (today) did all the characteristic bows-out-of-the-water stuff, but tucked in a "shoulder" as she rolled into the turns"
It was with a big, heavy pack, so I will try 7 cells and a lighter pack, also 9.6 V and see what happens!
As the current is very low (must be around 5A) I can try 8- pencell packs, of which I have lots from kids toys. Might also solder up a heavy-duty Li-ion pack or use a laptop battery as is (3S, 2P) and see how that goes!
andrew
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Andrew,
The noise sounds like driveline vibration.
In your pics there is a lot of unsupported weight revolving.
Is it possible to move the motor aft but shortening the inner propshaft.
If the outer prop tube is well supported at both ends this cant vibrate.
But with the length of the inner prop shaft and the unbalanced coupling there is a good possibility that the vibration is comming from here.
If it isn't possible to move the motor would it be possible to fit a small outer shaft epoxied into the hull.
This would only leave the coupling unsupported.
One last point, check the coupling ends as I have had some of these bored off centre!!
Bob
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Bob,
Thanks for your reply - it certainly is driveline vibration. I may have mentioned earlier that my local supplier of boat parts has supplied me coupling fittings which essentially do not fit the propshaft. So the coupling is not running true.
:}Holy grigoli! :}
had a session in the ice this morning (6.30am at Blaby wharf) tried 9.6V (8 pencells) and this is the dog's appendages. Got about 10 minutes running, good fun and some poor pictures!
However they do show how she looks at speed - the front is well lifted!
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04350.jpg)
Blurry - but see what I mean about the "wings" - the bowwave is rolled out sideways
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04353.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04348.jpg)
Not great pictures - I plead shortage of fingers and eyes
Steering habits - I'm getting used to her now - even with a the light battery pack she dips a shoulder and nearly stops in turns at full speed - next step is to add spray rails which should reduce this a bit.
Turns left much tighter than right - might be prop torque or my lousy rigging of the rudder linkage
Full power in reverse gives impressive speed, marginal steering and a fast stop
OK, so this motor needs at least 9V to be interesting, and the current draw is not excessive. The pencell nicad pack is probable rated about 1AH, so if it lasted 10 minutes it was drawing 6A approx - this seems close to other estimates. So a Nimh pack of pencells should nearly double the duration - and Li-ions will increase it a lot more
Still to try - an Overlander buggy motor - I willl return to 6cells to begin with
Outrunner bell motor - need to rig up a reverse (nother servo with microswitches) and find a coupling for it
andrew
a little euphorious
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Whenever I see models or full-size boats in a posture like this I am sure that they would go faster on the same power if we could get the bow down!
I am thinking strongly of fitting a (non-scale) adjustable planing tab at the stern to:
Get the bow lower
Lift the stern
reduce cavitation by preventing air entering from the stern
I'm thinking of something about 30mm wide, the full width of the bottom of the transom
I could either make it in perspex or similar plastic (so its not very visible) or include it in the Zebra camelflage so that you wouldn't know what your eyes were seeing
Could any speedboat experts tell me (a) if this is a worthwhile idea
and (b) if speedboats use flexidrive to get the prop drive axis more parallel to the water?
TIA
andrew
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A flexi has to be slung out at the back of the boat to have meaningful effect, which would mean having strut / stinger, rudder at the back etc, so wouldn't be feasible, trim tabs should be fine, but should be of metal construction, as perspex would need hinges and bolts to angle them, best off for a boat this size with a couple of strips of soft ally sheet epoxied to the underside or transom, because the stress is minimal, and you would be able to angle them with your fingers. You could paint them in matching hull colours and the bits sticking out water colour for camouflage.
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Andrew,
Before you get too worried about how she runs see if you can't find some photos of a pt boat at full throttle, you may find that she is running the same way the full size ones ran. If you look at the way the real ones were fitted out with all of their gear. The engines, torpedoes, fuel, and the largest gun were all in the rear. The only thing forward were the crew quarters, bridge, chart room and a fairly light gun. So I was thinking that they must have run with their bout of the water due to the weight in the back of the boat.
Andre
over yonder in Portland Oregon
PS I seem to remember them riding high in the front in movies but I may be mistaken. %)
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Higgins Pt Boats sit with the bows just clear of the water, so yours should be fine.
My Hellcat has somehow decided to be way too fast at full throttle, and sits with the waterline halfway along the hull and the tail nearly out of the water, planing and riding over waves like theyre not there, has the powerboats it lives with's blood running through it's veins. Because the powerboats it lives with have no blood left ok2
To reduce cavitation, you need to re prop, possibly a brass racing prop.
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Andrew,
Agree also, by referring your photos, it sits very nicely with scalelook attitude O0
BR,
Hannu
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Andre & all the Andrews
I note with the photo of PT658 that the machine gun tubs are further back from the helm than other Higgins I have seen. Is this a later design? See the photos below.
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Forgive me for my ignorance, but which PT is it you are building Andy number 1?
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AndyN,
Forgiveness is granted you :}
Believe me , if I knew I would tell you - Peter Miller is non-exact about the type or specific number, and I am too. It has roll-over the sied torpedoes, but a whole slew of assorted guns. I instinctively like the earlier boats like 235 pictured (or retouched) but don't want the highly-angled tube launchers.
I'll let you know the moment I do - I have all the pics on 658, but still want the zebra scheme
Hannu, thanks for the comment - this was some trial outings to see what I could learn - and I have liked what I saw.
I would, of course like to get some weight out of the boat - I have a 540 buggy motor which should do the trick without drawing more than 30 Amps :}, and I will make up some 2S;2P li-ion packs.
But mainly fit the spray rails, gunwale rubbing strip and stern bumper as well as the basic deck clobber then get lots of pale grey paint on her.
I am wortking on the theory that the Zebra camelflage measure would have been black on white, but I will use dark grey on light grey with tiny additions of "other"
andrew
(been sidetracked to finish my submersible Footy racing yacht - as you do)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/Footys/ZBF/DSC02344.jpg)
Pic of ZBF on the right next to my Razor on the left
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Hi Andrew
I have more photos of Higgins like the 235 if you would like me to post them. Myself I prefer the torpedo tubes and I have seen them in line as apposed to them being on the angle. The tubes have a system when ready to launch of being manoeuvred outwards so as to clear the sides of the boat and then be retracted.
Regards David
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The problems with the tipping topedo launchers always was that the sea corroded them and they stopped working, so crew members literally had to kick the torpedos off the sides of the boat.
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Andy, I can well imagine this happening!
There is nothing quite like kicking a primed Torpedo with a pair of contra-props which can spring to life any time :}
Well its been a Good news, Bad News weekend (PT boat wise)
Good news: The coupling I have fits the shaft exactly - and always did!. The Graupner shaft is stepped down from 3mm to about 2mm for the last 20mm of length - I was trying to fit the coupling to the 2mm portion of the shaft - shows how much I know about boat hardware :}
That explains all the thrashing, vibration and noise when running.
Bad news - I had unkind thoughts about the supplier of the parts
More good news: I have fitted the spray rails and rubbing strakes, and got them dope-sealed, made good progress with the deck house. I am taking the layout and detail of this from PT568. The gun tubs have been cut from a length of plastic tube I have of the right diiameter with the top flanges from styrene sheet cut with a circle cutter.
I aim to get most of the fixed deck fittings in place before diving in with the paint primer/undercoat
I will do a post on the spray rails later just in case it helps anyone getting close to that task :}
andrew
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Spray rails etc.
Hull is covered in heavyweight tissue and doped heavily, so its time to fit spray rails, rubbing strips round the edge of the decks and a bumper across the transom (seen in restoration pics of PT658)
A quick scout through the strip wood I have available turned up some 1/16 square for the top rails and some 1/8 sq (both balsa) for the spray rails. They are all medium hard wood - so i filled a tall thermos with boiling water and dunked them for an hour or so.
When they were nicely "al dente" I brushed the water off with my fingers and pinned them in place round the hull - with some rubber bands at the bow
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04396.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04397.jpg)
Next day they had set in a good curve so there was no bending to do while gluing them in place.
Balsa glue (well if it works for Glyn Guest, who am I to argue?) and pins got them fitted (I had rounded the bow ends carefully before doing the glueing)
Note: none of the rails on a Higgins actually reach the bow - the rubbing strips are tapered off in the last foot (full size) and the spray rails also terminate short of the bow - there are good pics in
http://www.savetheptboatinc.com/photos.htm
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/scan0076.jpg)
Also the spray rails do not reach the stern - the rail from the bow stops ahead of the front exhaust (where there is a tapered "chock") and continues between exhausts 2 and 3 where it stops completely - there is no spray rail between exhaust 3 and the stern.
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04400.jpg)
This is the morning after doing the hot bending - the first rubbing strip has a good permanent bend
So now the rails are in place, and have been sanded and doped
I will be spraying the hull, but not until I have done the exhausts, which are so much of the character of a Higgins boat that they need considerable care. I am also mortally afraid of Andyn's eyebrow if I deviate from scale :}
Boat will probably be in the car for the warwick show - on the friday. I will be (modestly) badged if anyone is interested
andrewH
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Coming along nicely, the eyebrow will stay down for now ok2
Found any good diagrams of this splinter camo yet? I have one somewhere if you want it
I'm going a bit scale mad now, I'm just about to take purchase of a Revell Smit Houston tug (reserved for friday in the model shop). Build thread will follow shortly, I expect it to be the backup Andy thread :-))
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Andy, Thanks. Sorry to have missed meeting you over the weekend
I wil try and give your eyebrow a long rest, but i suspect that you are basically a better scale modeller than me, so it won't be permanent.
Today I'm a little euphorious - had a generally very good weekend and had a GREAT trial of the PT boat with non-wabbling coupling! Night and day difference - smooth, quiet and faster :}
The weather was just turning pear-shaped when I took the pics, and only two of them are worth seeing.
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSC04426.jpg)
Imagine a low hummmmm and this. By this stage the battery was down in the mid-voltage
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/th_MOV04431.jpg) (http://s222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/?action=view¤t=MOV04431.flv)
not the world's greatest video, but it gets better (briefly)
andrew
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Andrew, It's looking great, any updated photo's or movies? How did the ZBF do? It sure looks unique, do you have a movie of that one under sail? Cap
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Now the doping on of the tissue - this is venerable heavyweight model tissue - applied wet (damp) and applied with thinners in the time-honoured way - it went on very well, with (near-) perfect smooth surface, and reasonable edges.
[/quote]
Andrew
I read your Higgins progress with interest. O0
But having just "Dope and Tissued" a similar hull using the GG method of applying the tissue with a "dollop" of dope and then laying it down with full brushes of neat dope, I was intrigued to read your method with the tissue applied damp. For the uninitiated, could you give a brief idea of how this is achieved.
Regards
Barrie
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As I was saying........
Sorry about the gap in communication - I have been doing some real life, running this boat very briefly with a brushless at Wicksteed, building and sailing Footys and quietly making bits in the background
The story so far:
Hull all complete, and running trials completed with both S600Eco 7.2, brushless 2210/21 (1200KV) and 540 buggy motor
beginning to complete deck fittings, armaments, etc.
I will also reread the thread, re-apologise to all the andys, and catch up with the questions/barracking/applause etc
Promise
This is where we were last night
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1557.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1559.jpg)
The lifeboatmen are just visiting to keep the scale in mind!
I have been scared of making the Higgins eXhausts - 3 per side. Pete Russell ignored them, but it ain't a Higgins without them
Mine being electric I have routed the exhaust electrons to come out of them (under water at displacement speeds) :}
andrew
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EXHAUSTS!
The Higgins boats ran their exhausts directly to the side of the boat level with the engines - each bank of each engine having its own exhaust.
The shape of these is quite subtle,
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCN1717.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/PTrepair007.jpg)
and my attempts so far have just exactly not achieved it (so far)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1555.jpg)
I am going to cast the exhausts in epoxy filled with microbaloons, so I need to make a mould and to make the mould I need a pattern for a LH exhaust and a RH
I will continue with these patterns to sort out the mould and method, but make much more scale ones before attaching anything to the boat. I woldn't want andyN to have to lift an eyebrow :}
andrew
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While confessing to less that right shapes of the patterns, I can also confess to "NO CURE whatsoever" of the silicone used to make the mould!
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1563.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1564.jpg)
The baby pink stuff is a 2-part silicone rubber. This particular one is a VERY high thermal conductivity potting agent that we use at work. It often doesn't cure, and this one hasn't.
It has a very subtle cure system,and is five years out of its date, so no great surprise there :}
I have cleaned off the patterns, and will try more silicone, and also possible plasticene to mould in
As you can see from the picture I tried one side lying on its back in a balsa box filled with the silicone - this SHOULD and prolly did eliminate air bubbles. The other side I just pushed into a puddle of silicone. In hindsight I realise I have but used any release agent at all - so if the silicone had cured I would have had a third confession to make.
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1125.jpg)
I like this pic - Bill the lifeboat is getting a good vew of approaching bank
andrew
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Update on the detailing of the PT boat
What a lot I learn as I do things - I knew vaguely that the Bofors (40mm) fired "clips" of 5 rounds, and that these are dumped into the holder above the breech.
Now thinking about that - say they fire at one round per second (almost certainly faster) then the clip is used up in 5 sec or less - so someone has to drop in new one, or it all goes quiet :((
It can't be the two gun crew, so it must be a loader or two standing behind or beside the gun and reaching over the rails at behind the breech. They would have to keep their piggies (and all other bits) well out of the way of recoil, etc!
I have some pics of the story so far with guns, torpedoes getting made
Torpedoes are rolled tubes of laminating film with foam fronts and balsa sterns. Not my most glorious modelling success, but very light and not too bad for stand-way-off scale
pics follow - they are (slowly) uploading into p/bucket so can't do anything till that has finished
THe Higgins exhausts have been fiitted and painted - they DO look like exhausts - just not the right shape for Higgins boats - sorry, Andy :((. Anyway a new and useful technique learned!
In the course of doing the mouldings I tested out a drum of about 10gall (imperial) of polyester resin which I was given many years ago, and was bought in the 1970s. Still works!
pics when they have loaded
andrew
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It's looking good, Andy #1 :-))
The Hellcat didn't have a Bofors, it had three 50 caliber machine guns. I think...
Found this: http://books.google.co.uk/books?id=XvJS9HYMnV4C&pg=PA77&lpg=PA77&dq=higgins+hellcat&source=bl&ots=hUW158JKvD&sig=dAX8cjXu0lM8yOfMm280VbX9SCs&hl=en&ei=LN6TSrfIA9yNjAfskaWDDg&sa=X&oi=book_result&ct=result&resnum=4#v=onepage&q=higgins%20hellcat&f=false Page 76 - 78
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True, Oh King, and this one is a 78foot Higgins - not sure what Pete Miller based it on but it has its gun tubs NOt where any pic or plan that I have seen includes them
Never mind - its generic (or I havn't found the pics yet)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1715.jpg)
The lifeboat men (George Turner 1/32nd) got pressed into service here tooo
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1823.jpg)
(http://i222.photobucket.com/albums/dd159/andrewh_photo/higgins%2078foot/DSCF1826.jpg)
it floats too, but the pictures havn't uploaded!
andrew
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Looks good Andrew ,heres the one i built several years ago for my son.He still has it but hasnt ran her in about a year,when we first fitted the 540 car motor my god it was way too fast but i think the motor is now past its best and its a lot more scale speed so to speak .Anyway heres the vid from her maiden voyage on christmas day 2006 running arround half speed with a weak battery lol.
http://www.youtube.com/watch?v=S5WPQneDh7o&feature=channel_page (http://www.youtube.com/watch?v=S5WPQneDh7o&feature=channel_page)