Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: PeachyPM on December 17, 2015, 07:11:12 pm
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“The First rule of FE club is; Nobody talks about FE club”
Well that’s how it sometimes can feel to outsiders, possibly because the competitive instinct of keeping the things that make your boat fast close to your chest!
But what I want to try to do is break down some barriers to a small part of our great hobby that I’ve only recently got involved in.
I got lucky, I met some FE chaps who race at my local club, one of them let me have a go with his Mini-mono and I was hooked. I bought a couple of second hand boats, re-furbished them with helpful advice and got racing.
Now I want to tackle my own build, but couldn’t find many topics or current advice on MBM and I wondered if this silence was a contributing factor to the apparent low numbers of FE racers in the UK, (compared to the rest of Europe, the Far East & the States)
I’m hoping to show with this build blog that most of us with some model making experience can build a boat capable of competing in at the very least, local championships if not quite hot enough for the Nationals or the World championship.
Please remember this is my first build and most of what I’m doing is based on very welcome advice from a very helpful FE community, but please, by all means chip in!
P.S. Re "the first rule"; the motor and prop in the photo’s won’t be the ones I’m racing with…but I will give ball park details to help with first timers who might want to get involved.
Here are some helpful links to clubs in almost the 4 corners of England, if any of our UK cousins know of a club championship in Scotland, Northern Ireland or Wales, please tell me.
In the North; http://www.ampdraggers.co.uk/ (http://www.ampdraggers.co.uk/)
In the East; https://ostendospreys.wordpress.com/ (https://ostendospreys.wordpress.com/)
In the South; http://www.electrafying.com/ (http://www.electrafying.com/)
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394 (http://www.swambc.webeden.co.uk/#/swarm-home/4581722394)
[size=0pt]For rules & boat classes; http://www.mpba-fes.org.uk/ (http://www.mpba-fes.org.uk/) & http://naviga.org/index.php/en/ (http://naviga.org/index.php/en/)[/size]
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Ok, so enough bla!
First picky, is my newly bought Lindenau designed mono 1 hull, I’m not sure of its provenance as I bought it second hand but un-worked from a private individual I found via the FE community. It’s a bit rough around the edges/seem, but nothing I can’t handle…..
First job, fit the flood chamber….this should be down as much of the port side of the hull as is reasonable. The idea is that when the boat (and it will) flips, porpoises or dives under it will fill the chamber which in turn rolls the boat over enough for the prop to re-engage. As the boat moves off the water empties out of the step & transom and the boat gets back onto the plane.
Pic2 is a thin sheet of GRP marked & ready for cutting, that I will use to make the wall inside the hull;
Pic3 is the wall fettled and dry fitted
Pic4 Then glued in place
Pic5 You can use whatever adhesive or resin you wish, I prefer 2 part Acrylic from;
http://www.adhesivebrokers.co.uk/ (http://www.adhesivebrokers.co.uk/)
They are a small & helpful company with massive amounts of experience selling to the modelmaking & film industry (I swear by their superglue as well)
Pic6 To seal this wall all the way down to the bow was proving tricky so my apprentice model maker was employed!
Pic7&8 Now to cut out the transom drain;
Pic9 Then the Step drain
Pic10 Now for some breather holes, these have 2 jobs, the first is to let air out & water in when the boat is upside down (air pockets will stop the boat self-righting) then to let air in to help the water evacuate as the boat moves off
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Looks great mate, can't wait for it to terrorise... er, I mean, "grace" the club lake! :}
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Looking good, i'll be following your posts with great interest over the coming weeks.
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Hi Christopher
Are you going to be mounting your rudder on the flat section where you have put the three bolts in?
I'm just about to mount the rudder and was not sure if i should mount it there as it is very close to the center line of the hull
Thanks
Steve
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Hello Steve,
Yes that's where I've been advised to place it, I must admit I also thought it was a bit close - jury's out on that one, once I've placed my shaft I'll mount my intended prop and have a think about it, perhaps I'll have to space the rudder blade out a bit, couple of posts down the line me thinks! :embarrassed:
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:-)) Thanks IKB & Hydro-monkey for joining in! :-))
From now on I will be pretty much “just” bolting kit on, so at this stage I want to tidy up the hull.
So first off, a good de-grease with panel wipe, prep clean or even white spirit. Tip… do this with the hull reasonably warm as the Gel coat has waxes in (otherwise it would be tacky to the touch just like normal lay-up resin) and any wax that has leached to the surface needs removing, I then “cut” the whole hull with 800 grit wet & dry.
Next step is to make good the transom, rails and sheer lines, (apologies if I have the terminology wrong) these need to be nice and sharp, this helps the boat leave the “grip” or “suction” of the water allowing it to get up out of the water and onto the plane.
I use car body filler, it’s perfect for the job and designed to bond well to fiberglass.
After this a quick whiff over with white primer, just to see how she’s doing. Don’t go too thick, it’s just to help you see how tidy your work is.
Pic1. Tidied-up step drain
Pic2. Sharpened up transom
Pic3. Whilst working on the hull I want to make the hatch fit better (actually I mean fit!)
Pic4. So first I made some masking tape templates as a rough cutting guide
Pic5. Then it’s a case of trim, try, trim, try, trim etc etc ………
Pic6. At this stage I’m happy with the fit, but the GRP still needs its “memory” to be changed, so I will be heating this up till it is very floppy and then taping it in place to cool down.
In the North; http://www.ampdraggers.co.uk/ (http://www.ampdraggers.co.uk/)
In the East; https://ostendospreys.wordpress.com/ (https://ostendospreys.wordpress.com/)
In the South; http://www.electrafying.com/ (http://www.electrafying.com/) & http://shpowerboats.co.uk/ (http://shpowerboats.co.uk/)
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394 (http://www.swambc.webeden.co.uk/#/swarm-home/4581722394)
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Now for some bolt-on items, the rudder bracket and turn fin bracket. you can buy these, but I wanted to make mine so they would fit the odd shaped Lindenau hull and look a little more bespoke (and if I can’t make my boat go fast yet, the least I can do is make it look good) I’m going to make mine from pre-preged carbon fibre sheet, there are plenty of places on the tinter web that you can buy this from, but take my advice, don’t buy the cheap stuff it will fail! If you are on a tight budget, you can make these parts out of strips of aluminium, it’s only a few grams heavier and you might have to bend it back into shape after a prang but at least it won’t just shatter like the cheap carbon fibre does.
http://www.easycomposites.co.uk/ (http://www.easycomposites.co.uk/) is a reputable company with whole range of kits and tools plus plenty of advice.
I first made some cardboard templates, and then transferred them onto the sheet, you can cut CF with pretty much anything but the range of tools from perma-grit are by far the best, everything else gets worn down very quickly. Always cut near but not on the line as CF will always have a fluffy fibre edge after cutting, this is easily removed with sanding and although messy, actually sands really well.
Two things to consider;
- If you use a band saw or any wood cutting saw, don’t use your extraction as CF will spark when cut and you don’t want to suck those sparks into your sawdust bag!
- Watch out for the CF dust, it conducts electricity and will ruin the motor in your dremmel, also keep it away from your boats motor!
Pic1. Small jigsaw is perfect for this sort of work
Pic2. Finished CF rudder bracket & fin mount
Now for the turn fin which I will fabricate out of aluminium.
This will be mounted on the starboard side of the hull and is shaped for right hand turns as this boat will mainly be turning right! The idea is this gives something for the rudder to work against don’t ask me about the shaping, I’m just copying what you can commercially buy!
Pic3&4. Shows my initial sketch spray-mounted on to the ali & the fin rough cut out ready for final finishing.
Pic5. The finished mountings in place with a bought water pick-up rudder and my turn fin.
The reason for the one bolt in the turn fin is so it will allow the fin to pivot at this point if it ever strikes an object, the bottom bolt in the rudder bracket will be replaced during racing with a sacrificial M4 plastic bolt, which will shear & allow the rudder to pivot in the same way. Without the ability to “get out of the way” a lot of unnecessary damage can befall your boat with snapped brackets, wrecked rudders and even holes ripped out of your hull!
Pic6. As we found out earlier with the flood chamber, the insides of these hulls can be quite difficult to access, even before they are full of hardware, so after bolting these items on I encapsulated the nylock nuts in acrylic adhesive, sorry about the mess, it looks untidy but works brilliantly.
In the North; http://www.ampdraggers.co.uk/ (http://www.ampdraggers.co.uk/)
In the East; https://ostendospreys.wordpress.com/ (https://ostendospreys.wordpress.com/)
In the South; http://www.electrafying.com/ (http://www.electrafying.com/) & http://shpowerboats.co.uk/ (http://shpowerboats.co.uk/)
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394 (http://www.swambc.webeden.co.uk/#/swarm-home/4581722394)
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Very nice work mate, liking the carbon fibre :-))
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Cheers Alex, at least someone noticed! :-))
The next item I need to turn my attention to is the steering. First the servo, there are of course a number of ways to mount the servo, the choice of which is mainly personal preference so here’s mine; I wanted to mount my servo in the same plane or aspect as my rudder arm/tiller, but this boat has a vee hull which doesn’t lend itself readily to mounting a servo square, either up-right or on its side.
Pic1. So I made a carbon fibre mount (first making mock-ups out of cardboard) this was glued in place then a commercially bought Ali servo mount bolted to this.
Pic2. I positioned this with the centre of the servo horn directly in line with the rudder, and as near to the transom as possible but still allowing access to the bolts securing the servo.
Pic3. Shows a stub of 10mm dia Ali tube which has been glued in place with acrylic adhesive that allows the linkage free movement through the transom, kept waterproof with a rubber billows style grommet. This will be secured in place by a small cable tie after the hull has been painted.
Pic4. Now for the prop shaft, the one I bought was over-long for this hull and needed cutting down, otherwise the motor would have ended up too far up the bow and I would have had problems balancing the boat & maintenance access to the motor itself. I sourced the correct diameter Ali tube to support the CF main shaft from a supplier on e-bay and bought a 100mm length only for a few pounds, and proceeded to the heart stopping surgery of cutting quite an expensive piece of hardware in half!
I removed 90mm of carbon shaft, cleaned up the ends and then bonded the whole thing back together. This operation isn’t for the faint hearted and I won’t be planning on repeating the same procurement mistake again!
I mounted my shaft approximately 5mm starboard from the centreline of the hull, this offset is to counteract the torque of the motor. One important thing to note, the shaft needs to be offset parallel with the centreline which means the motor mount needs off setting as well.
Now for the battery mount
Pic5. Some people like to Velcro their batteries down, which can be perfectly acceptable but if the Velcro adhesive is softened by water or shaft lubricant/WD40, there is a chance they can be thrown lose just when you don’t want them to be! A lose pack 280g of cells can make a mess of your set-up!
I’ve made mine from a piece of Ali L shaped angle bonded in place and added a Velcro strap to secure the cells.
And now for the cooling system which is a very important part of the boat.
The build-up of heat can wreck the motor, the ESC and Lipo cells. (you really don’t want a catastrophic failure of a large pack of lipo cells in a little GRP boat).
Pic6. Shows the start of the water’s journey from the rudder pick-up through the transom (via a bonded Ali tube)
Pic7. Then it connects to the side of the battery mount (not essential but at £50 a pack – why not help keep them cool?)
Pic8. Then it will join a water cooled ESC (on its way from HK at the mo)
Pic9. Then on to the motor mount. I’ve chosen a water cooled mount instead of a water cooled jacket that surrounds the brushless in-runner because I want to get the angle on the prop shaft to the bottom of the hull as small as possible. This sort of mount allows me to get the motor right down in the bottom of the hull. It’s not as efficient cooling wise so I will be adding a snap-on set of cooling fins to the top of the motor to help.
Pic10. Shows the final run of tube which is attached to an exit nipple out of the side of the hull (above the water line of course)
In the North; http://www.ampdraggers.co.uk/ (http://www.ampdraggers.co.uk/)
In the East; https://ostendospreys.wordpress.com/ (https://ostendospreys.wordpress.com/)
In the South; http://www.electrafying.com/ (http://www.electrafying.com/) & http://shpowerboats.co.uk/ (http://shpowerboats.co.uk/)
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394 (http://www.swambc.webeden.co.uk/#/swarm-home/4581722394)
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Almost at the finish line! :}
In the North; http://www.ampdraggers.co.uk/ (http://www.ampdraggers.co.uk/)
In the East; https://ostendospreys.wordpress.com/ (https://ostendospreys.wordpress.com/)
In the South; http://www.electrafying.com/ (http://www.electrafying.com/) & http://shpowerboats.co.uk/ (http://shpowerboats.co.uk/)
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394 (http://www.swambc.webeden.co.uk/#/swarm-home/4581722394)
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So I’m about ready for final prep for paint, and I thought this would be a good opportunity for the Imperial pit crew to put his X-box down and pick up some tools!
My boy did a great job striping the Lindenau down, he even wanted to do it! Bonus :-))
In the North; http://www.ampdraggers.co.uk/ (http://www.ampdraggers.co.uk/)
In the East; https://ostendospreys.wordpress.com/ (https://ostendospreys.wordpress.com/)
In the South; http://www.electrafying.com/ (http://www.electrafying.com/) & http://shpowerboats.co.uk/ (http://shpowerboats.co.uk/)
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394 (http://www.swambc.webeden.co.uk/#/swarm-home/4581722394)
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Hi Chris. You seem to be making a cracking job of the build, keep going and let me know when sea trials are going to be held. (I could really do with some of the acrylic glue) :-)
Ian.
8)
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thanks for the vote of confidence Ian, I've got plenty of the acrylic goo!
Sea trials will probably be next year as I'm waiting for a motor coupler & ESC & there is if course Christmas to deal with, sorry I meant enjoy!
When she hits the water perhaps you can video it for me?
Chris :-))
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Looking awesome Chris, very nice Brass alignment tool you have there ;)
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I'm charging up the video camera now! 8)
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:-)) Cheers Ian :-))
A couple of cracks & dents have appeared during the build, so a quick fill & make-good with some car body filler was required first, then a coat of white primer. Then I give the bottom of the hull a coat of matt lacquer, the lacquer is to give a nice easy clean and tough finish and the matt because I like the contrast with the top of the boat which will be finished in gloss. This will be left to dry then masked off so that the top surface will have its final coat, application of stickers and then a final finish of clear gloss lacquer.
In the North; http://www.ampdraggers.co.uk/ (http://www.ampdraggers.co.uk/)
In the East; https://ostendospreys.wordpress.com/ (https://ostendospreys.wordpress.com/)
In the South; http://www.electrafying.com/ (http://www.electrafying.com/) & http://shpowerboats.co.uk/ (http://shpowerboats.co.uk/)
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394 (http://www.swambc.webeden.co.uk/#/swarm-home/4581722394)
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Looking good mate, looking forward to seeing the video of the trials
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Cheers chum, and thank you again for the brass motor mount tool, it worked perfectly, just the job whilst I wait for my ETTI coupler to arrive.
Photos of finished paint job to follow! :}
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Ok so here's some photos of my build fully painted and with all her bits bolted on, she still needs the ESC fitting and the motor coupler and I'll post some interior photos when they arrive. In the new year I'll do some test runs and hopefully have a video to post too! Until the Merry Christmas, the boat yard is closed! :}
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Excellent! :-))
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Looks almost professional! ;) {-)
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:-))thanks guys :-))
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Ok gents, all the turkey has gone and the mince pies too! So let's crack on with the build...
The ESC has turned up & so has the motor connector and the motor cooling clip on fin thingy. So below are some photos of all the kit fitted in place.
Next job will be self righting tests in the bath.
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Looks good mate, look forward to testing
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Quick last post of 2015, the boat is finished!!!!!
Today I ran a full test of the electrics, bound the RX, programmed my TX with slightly reduced rudder movement (80%) and programmed the ESC.
Then on to a bath test to see if she self-rights. She sits nicely with just the correct amount (I think) of port list whilst stationary.
I needed to add 10g of lead up the flood chamber and a further 5g of lead inside just to port of the prop shaft just to re-balance the centre of gravity at approx 210mm from the transom.
I made a small video of the self righting which I might have to post seperatly.
All that's left to say is Happy New Year & I'll post the results/video of her maiden trials in January.
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Looks good mate :-))
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Very interesting build, hope it goes as good as it looks :-))
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Hey peachie...this is a super tidy build with a mix of high strength composite materials and hardware :-)) and you have documented this well for us to follow
Not rivet counting, but for you records, the ballast block you nominate is 10gm of lead, however as show is stamped 10 Zn [lead is approx. 60% heavier than zinc]
Happy new year this 1st day of 2016........& looking forward to seeing images of her on the water O0................ Derek
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Cheers IKB & Knoby, it has been an enjoyable 1st FE build.
Derek, thanks for pointing out the weight labelling, schoolboy error on my part & of course I should have pointed out the reason for the use of zinc over lead when a weight is positioned in a place that has direct contact with the water. It's because at our lake we have it stocked with carp to keep the weeds down & as we all now know, lead isn't very good for wild life.
Are you guys down under now in 2016? We've got 2hrs to go and I'm getting the "look" from the missus!
Hope you all have a great New Year! :}
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Peachey....... back in post 1, you mention the following......
'P.S. Re "the first rule"; the motor and prop in the photo’s won’t be the ones I’m racing with…but I will give ball park details to help with first timers who might want to get involved' .....however I cannot see any reference to the earlier or final motor sizing
You also mention the 10gm of ballast to offset the motor torque effect
These brushless motors have considerable power & hence torque, however your actual propeller shaft appears to be in the slender region of 2.5 mm diameter....did you do the calcs. on the ballast positioning & requirement to counter the torque?
The other point to consider is that the torque moment applied is proportional to motor RPM, so will the vessel not suffer from a varying list to port :o, dependent on the vessels speed?............Derek
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I'm not really into fast electrics (yet!) but this thread has caught my interest. Well done peachy looks the part :-))
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:-))Happy New year to all Mayhemers! :-))
Merci, unsinkable2.
Hello Derek, thanks for the questions, I'll try and answer them.
1. For motor and prop spec, I've been given lots of advise ranging from 4600kv to 5000kv using a 38mm dia brushless with a can between 50mm & 65mm in length.
As for props, 1.4 to 1.6 pitch, 33mm to 36mm dia. With the smaller props being matched with the higher Kv/rpm. These are with a 2cell 7.4 set up.
My boat has a 33mm prop on it at the moment purely because that's the largest I have in my spares box. My final choice will be dictated by testing, I will be using borrowed props from some of my club mates and then will purchase whatever works.
2. My wire drive is 2.5mm but this has raised a few eyebrows amongst the racers I know, they all use 2mm!
3. The 10g of ballast is being used mainly to assist with the self-righting, although being on the port side (along with most of the heavy hardware) will help with countering the torque.
4. As for torque varying at different speed this isn't really a factor as the boat will predominantly be run flat-out at all times. The biggest problem is going airborne on an opponents wake as this induces a barrel roll which if not completed 360• will end up with the boat upside down.
So in conclusion; I won't know what motor/prop combination I will use or where I need further
ballast until I've run tests.
Ps I've been advised that building the boat is the relatively quick bit, setting it up for competition is where the real work starts!
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Thanks Peachy....[finally correctly the spelling...apologies]
1. It is clear that you are progressing in some sort of logical [researched] manner :-))
2. I find it difficult to comprehend how 2.5 diameter 'wire' drive can transmit this power
3. Is there any allowance for longitudinal [length wrap-up] length reduction due to rotational torque?
4. Without understanding the FE rules & regs, is a straight line start to finish [such as the Campbell/Bluebird speed tests] the criteria over a circular or semi circular like course?
As you will have realised, I too have little knowledge in this FE model subject....however find the engineering interesting
Derek
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Hello Derek, I'm still very much at the beginning of the FE learning curve and I hope a more knowledgeable modeller might be able to answer your questions.
My reason for the build blog was to try and "lift the vail" a little on the boat building side.
As for torque reduction over the length of the wire drive, I'm not aware of any, I do however know that this does happen with the flexi drive systems that some racers prefer and that are pretty much the norm with the Hydro out-riggers & Catamarans as the hull obviously sits up out of the water and a fixed shaft wouldn't allow the correct prop angle for surface drive.
As for race rules, we compete around an oval/loop course that starts with a 10s mill time to get the boats from the launch jetti, around the last course markers then under the start gantry. The race time from then on is 6mins. We complete 3 races in 1 meet with the best laps and overrun seconds from the best 2 combined.
Here are the links to the UK governing body (MPBA) who use the rules laid down by NAVIGA
For rules & boat classes;
http://www.mpba-fes.org.uk/
http://naviga.org/index.php/en/
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As promised, here's the you-tube link for the self righting bath test;
http://youtu.be/XlSm_F3YUnE
:-))
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Looks good Chris, hope the Carnaby 'breeze' doesn't stop it from self righting.
Cheers,
Ian.
8)
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Happy New Year Ian, I'm going to take more weights with me and do so tests near the waters edge I think!
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Today I completed a couple of tests with my Lindenau Mono1 and at least learnt a couple of things!
Remember this is the first Mono1 I have built and sailed and when I post some links to a couple of videos I won't mind if you have a good laugh!
The result of the test was that I do have a quick boat that gets up on the plane and is well balanced, although the ESC kept dropping out after a 30seconds of full throttle, I'm not sure if this was a programme problem or a doggey ESC. Also the steering was far too aggressive, and when I trimmed the rudder servo down to 40% I found to my cost that slow speed steering was very poor.
Unfortunately I ran out of water and the boat skipped out! Fortunately only minor scratches and some dinks in the prop, the sacrificial plastic bolt in the rudder worked and the turn fin pivoted out of the way just like they were supposed to do!
Here's a photo of the aftermath, I'll post YouTube links latter.
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Ok so here is the first test, as you will see the turning is far too sharp and at full throttle she spins on her own axis!! Not good, but at least she's balanced and fast, I'm thinking the rudder is to close to the prop so I will be swapping over the bracket latter but for today I just reduced the servo movement so I could at least get a run in! :}
http://youtu.be/G6B_qbtgGLM
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And here is the second run with a more gradual build up of speed... But then whilst trying to stay away from some scale chaps, I stupidly ran out of lake! Doh! :embarrassed:
http://youtu.be/dEGmezRAew8
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Good for you Peachy, you sorted the problem and are big enough to show your mistake. That aside it looks really fast. When I get around to building an FE it's this thread I'll be referring to. Well done! U2
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Cheers Unsinkable, it was fun...if a little embarrassing! My son had stopped filming so you don't here the big cheer from my club-mates in the background! %%
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Hello all, so after a long & helpful discussion on the "M section discussion group" https://www.facebook.com/groups/679193992180229/ (M section is a reference to NAVIGA's section reference for motorized models)
The chaps on there were very helpful and not at all condescending even thou my video of my first test left a lot to be desired!
So here's the list of what has been suggested I change;
1. change the motor from a 36mm can to a 28 or 29mm as the 36 has way to much torque which just flips a lightweight boat like this one. :embarrassed:
2. move the servo nearer to the transom to help with reducing any flex or flop in the steering.
3. test the servo for "glitching". I've done this, it does twitch at full power so I will be replacing this servo.
4. replace plastic servo arm with an aluminium one.
5. replace or strengthen the rudder linkage to reduce flex
6. move the center of gravity to 28% of the hull length from the transom (195mm as apposed to the 220mm which I have)
7. angle the bottom of the rudder forward by 1 degree to help keep the bow up (I inadvertently had it 1 degree the other way which would contribute to keeping the bow down and therefore digging in during turns)
8. replacing the swept back turn fin (apparently this style is mainly used on riggers and cats again to keep the bow down, I used it 'cause it looked good!) with a square fin. :embarrassed:
9. move the "kill loop" from the transom to the top deck as some if not most clubs would not allow this configuration to compete. I had only put it where I had because I had seen it on another boat & thought it looked neat! :embarrassed:
10. and of course finally fill & make-good the scratches it had received jumping out of the lake! (I know it will likely get more during a season but you might as well start tidy!) O0
This should keep me busy for a while, I'll post pictures when complete then have another go at testing!
P.s there were other suggestions, but these made the most sense and seamed a lot more practical to complete.
In the North; http://www.ampdraggers.co.uk/
In the East; https://ostendospreys.wordpress.com/
In the South; http://www.electrafying.com/ & http://shpowerboats.co.uk/
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394
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6. move the center of gravity to 28% of the hull length from the transom (195mm as apposed to the 220mm which I have)
Just a quick post to say my maths was wrong again!
28% from the transom on a boat that is 620mm long would be closer to 174mm {-)
{:-{ That's gonna be a task! First I'll try & get everything back as far as possible before I start sticking more weight in this boat.
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Peachy.............I assume the balance point is rather critical.....do you construct a sharp edged hull profile to mirror the hull profile, the gently adjust the fore & aft hull estimated placement until you achieve that pivoting balance & the measure this as the nominated balance point?........... Derek
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Never having built a FE what I say next may be total nonsense but...... If your balance weight is (just for example) 50g, would it be possible to have a nut or threaded disc on a threaded bar from say 150mm to 180mm. The total weight of the bar and nut or disc being equal to the 50g (or whatever your weight is) this would mean you could spin the balance weight forward or aft 15mm to fine trim the balance point. Or is this %% {-) {-)
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Hello Derek & Unsinkable,
In answer to your question Derek, I use my boat stand but I tape two 5mm ball bearings on top of one of the up-stands so the boat is just sitting on the two spots at the back with the bow resting in its cradle. I then slowly push my boat back & forward until it just sits up at the bow so that the bottom of the step & the bottom of the transom are both in line horizontally then I can take a measurement with a small steel rule (see photo, although you cant see the BB's they are there) I used this because the hull changes shape along its length. ok2
Unsinkable, I've not seen such a devise in use but I guess the principle would work, however I am finding out the the secret to a fast boat isn't just one thing, but the some of its parts, and the ability for the boat to self-right has also to be considered when placing weight so I'm not sure how this would work, it might be more practical on a bigger boat. :-))
In the North; http://www.ampdraggers.co.uk/
In the East; https://www.ostendospreys.wordpress.com/
In the South; http://www.electrafying.com/ & http://shpowerboats.co.uk/
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394
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Ok, so the next job I've tackled is a hydrodynamic problem. I knew that to help the boat get up on the plane, you need to reduce the "wetted area"of the hull, this is why the mono hulls have steps, I also knew that the sharper the chines were the easier the boat would be released from the grip of the water. I assumed that a nice clean smooth hull would work perfectly as long as the chines, step & transom were nice & sharp....but it was pointed out to me that maybe a contributing factor to my boat running "wet" (not up on the plane enough) could be hollowing under the hull, which apparently works like a hydrodynamic version of ground effect in that it sucks the boat down onto the water surface.
To fix this I first needed to spot any convex hollows in the hull using a metal edge and a back light (see photo) and guess what? I found plenty! :((
so on with the filler, then off with the filler using a very hard and perfectly flat sanding block.
Right...on with the paint!
In the North; http://www.ampdraggers.co.uk/
In the East; http://www.ostendospreys.wordpress.com/
In the South; http://www.electrafying.com/ & http://shpowerboats.co.uk/
In the West; http://www.swambc.webeden.co.uk/#/swarm-home/4581722394