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Author Topic: ULCC build  (Read 29648 times)

AlisterL

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Re: ULCC build
« Reply #25 on: October 04, 2009, 04:24:57 AM »

One more thing that I thought of.
I needed to chamfer the edges down the length of the hull, like so:



I did this with a small (modellers?) spokeshave:


and some 80 grit sandpaper. Basically I used the spokeshave to take the edge down at about a 45 degree angle to the depth I needed, then repeated the process at the 22 degree angles and tidied it up with the sandpaper.
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Alister

AlisterL

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Re: ULCC build
« Reply #26 on: October 17, 2009, 09:58:35 PM »

Last weekend featured bathurst and even though I'm neither Australian nor in Australia, that took up a fair chunk of time. Mostly I think I slept through it :) Ha ha - well not quite. Any comment on the result might turn into a rant - so I better stop there!

I noticed that, despite my best efforts, the bow was getting small dents and knocks made in it, ruining all the work I had done making it smooth and presentable. I resolved to get some epoxy on the hull to protect it from knocks and also as a water proofing coat.
This has turned out to be a small challenge as one can never be quite sure what coverage will be achieved.
First of all I did the underside of the hull. Having previously bought some epoxy and used it to strengthen the inside of the balsa planked bow and stern I figured I'd start with 25mls of epoxy and see what happened. The first 25mls seemed to cover about 1/2 the underside without too much trouble. Interestingly however was that after it had dried, the epoxy appears to have "retreated" or pulled back from some small areas while it was drying, leaving some small uncovered patches. I'm not sure if this is normal behaviour or not, or if it means that I really didn't have enough to cover the area I was doing. I ended mixing another 25mls to cover the remainder of the underside - not including any of the stern area. I also managed to brush some around the bow area too.

In hind site, trying to "stretch" the coverage out was a bad idea. Irrespective of the coverage problem with the epoxy above, where it was very thinly applied or brushed out too much the surface has become quite rough on drying.

I figured that this was mostly to do with coverage and so yesterday when I repeated the procedure on on of the sides, I made sure that I used more epoxy. To cover roughly the same length of hull, but probably a little less than 1/2 the total area I used two 20ml mixes. This has resulted in much better coverage and a much better finish to the epoxy.
This snap was taken yesterday afternoon after the epoxy had hardened and I was able to see the result:



After the first coat to the underside and having noticed the problem with coverage, I went around with a big black marker and circled all the areas where there were problems. One of these you can see on this side in the photo. The coat I added over the top has totally covered that up. What you can't see is the number of circled areas on the underside! Perhaps interestingly, many of these areas are around the screw heads that have been filled and sanded smooth. However, that wasn't a problem on the side.

Because I was now putting epoxy on the hull, I figured I better sort out what I was going to do with the rudder. I knew and had planned to add a length of metal from the stern out to the correct length matching the plan. Although I new I had to do this, I hadn't and still haven't figured out how to go about allowing rudder to be removed if needed. So, having salvaged some nice lengths of metal (for the IT inclined, these are unused rails for rack mounting Cisco MDS switches) I cut a length and trimmed it to width and put it in place. Due to a lack of inspiration I have the heads of two screws protruding from the surface of the metal. I wasn't sure about coutersinking them - mostly as they are round heads and not countersunk flat heads and also, they protrude only 1mm. In the photo, that piece of metal is a fraction under 70mm long with 50mm hanging out past the end of the skeg (skeg?). The actual pivot point for the rudder is 22mm back from the end of this piece.
I think I will have to figure this all out once and for all before any epoxy fixes this in permanently.



By the way, there is a hole for the rudder tube - I just planked over it. it's also easy to see how thin that balsa got...
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Alister

ZZ56

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Re: ULCC build
« Reply #27 on: October 18, 2009, 10:25:05 PM »

The most common way to service the rudder is to make the bottom bracket removeable.  Then you'd take the tiller arms off the shaft and slide the rudder and shaft down and out. 

If you fixed the bottom bracket in place permanently, you'll need to make the rudder removable from the shaft.  You can use an integral stop collar to attach it to the shaft or make a square shaft that slides inside the rudder as i did



The bow is looking fantastic so far.  Instantly recognizeable as a big tanker.
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cbr900

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Re: ULCC build
« Reply #28 on: October 19, 2009, 01:03:01 PM »

Alister,

Comment away on Bathurst mate, no one can deny that on the day the best combo won,
end of arguement.............. :-))


Roy
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AlisterL

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Re: ULCC build
« Reply #29 on: October 23, 2009, 11:18:15 PM »

Hi ZZ, I spotted that diagram on your build and had been thinking about it - thanks for reminding me.
The problem that I'm going to face is that I will not have access to the rudder shaft to remove the tiller arm. It will be well back from any superstructure that will come off the deck allowing access.
I think the easiest thing to do will be make that piece of metal at the bottom removable - or allow it to swing from side to side. I just have to figure out how to make it watertight - I'd hate any water to get into the ply.

I was just sitting here thinking about it and, finally, inspiration has arrived!

Hah - and I even did a little sketch to illustrate, but postimage isn't playing ball, so let me paint a picture in words...
Referring to the previous image with the metal rudder support attached, imagine if you will, a vertically square section cut out of the ply where the rudder support is attached. So above the end of the shaft, there is a section removed from the ply. Picture then that section being replaced by a square section of plastic exactly the same size inserted. This then has the screw holes drilled into it and is glued firmly in place. The rudder support screws into this and because it's plastic and waterproof there are no problems with water getting into the ply. Heck, I can even cast that with the epoxy I've been using to coat the outside of the hull...
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Alister

AlisterL

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Re: ULCC build
« Reply #30 on: October 23, 2009, 11:25:07 PM »

Roy!

I've been avoiding replying to your post since I saw it! I may be able to reply now without getting carried away...

Suffice it to say that I do have a Commodore (wagon) parked in my driveway, but I still didn't really think GT should have been the winner - there were two incidents after the last safety car during overtaking manoeuvres that really, I felt, should have resulted in some sort of penalty to that car, particularly that close to the end. I wasn't the only one watching in our household who thought the same. And when GT was asked about it during the press conference, his reply was something along the lines of "stiff, it's Bathurst". I wonder if he would have been so generous if he was on the receiving end... And lets not mention the commentators, for whom some drivers can do no wrong...

And I've already said more than I wanted to :)

Back to the model boating...
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Alister

cbr900

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Re: ULCC build
« Reply #31 on: October 24, 2009, 11:55:34 AM »

AlisterL,

Just curious, and yes I will agree there was a little bit of unusual driving by some people.

The other incident which I disaggreed with was the Vodaphone Car taking out Bargwanna
on the main straight entry, he was in the replay into the back door and not upto the door
post, but no action was taken, so I guess it cuts both ways, I am not a follower of either brand
having owned both types and had no trouble with either............


Roy
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AlisterL

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Re: ULCC build
« Reply #32 on: October 24, 2009, 09:08:06 PM »

Fair point Roy, very fair point. That was something I had forgotten about. 6 of 1, 1/2 a dozen of the other perhaps...
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Alister

AlisterL

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Re: ULCC build
« Reply #33 on: October 24, 2009, 10:09:34 PM »

Postimage seems to be responding to me to day, so here are some relevant snaps.

First - the on-paper drawing of what I tried to explain yesterday.



That was white paper....

The cutout I made above the propshaft:



I have had a scrape at it with some 80 grade sandpaper to key the surface for the glue.

And lastly, the mould, as such it is...



The glue was drying in this shot.

I made, purposely :), the mould larger in all dimensions that I needed. Also, given this was a first attempt for me I used balsa to make it, on the basis that I could sand it away if I needed to. It looks like I will need to...

Anyway, TTFN.
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Alister

AlisterL

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Re: ULCC build
« Reply #34 on: October 26, 2009, 03:43:04 AM »

Skipping right along a bit, we find the following:



Funny how the macro feature on the camera shows lots of stuff I didn't notice with the naked eye - particularly that edge that has been sanded away...
All up I consider that a success. There is still some work to do to make the rudder removable, but most of the tricky bits will be in the rudder itself I think. I can progress further with the epoxy.

Computers are much easier in case anyone is curious :)
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Alister

AlisterL

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Re: ULCC build
« Reply #35 on: October 31, 2009, 09:46:52 AM »

Well... so... interesting week... I covered the final area of the hull with epoxy on thursday night. That means the outside of the hull is fully waterproofed... That means water... And weight...
Speaking with a friend about it, we did a rough calculation and divided the DWT of the Jahre Viking/Knock Nevis (565,000) by the cube of the scale, 27000, giving 21 Kg. That's about as heavy as I feared...

So anyway, lets find some water to do a test float. It won't fit in the bath - about 200mm too long at the longest point on the bath (way up the top) . The in-laws bath is triangular - it must be at least 1500mm at it's longest. Hull in the car, kids too 'cos they wanted to watch and up to the in-laws... Hah! Foiled! The triangular bath is only about 1300 along it's longest side... Finally I decided to wip the paddling pool out of a cupboard in the garage - I knew that was 2m long...

Where the hell did the link to upload photos to PostImage go..? I must be going blind...



Well anyway, one hull in a puddle. Nothing in the hull as yet, just a pro-shaft! It actually sat lower than I thought it would. The sharp-eyed will notice on the side of the hull three black dots, one at each end of the centre tub and the other pretty much in the middle of it. This is the scale water line. I'm not using this as a target - I figure that if I'm a centimetre or so below that mark then it will be good enough. Quite frankly at the ponds I normally use, anything less than 3cm of freeboard is going to be dangerous. I suspect the natural state of the my local waters is probably the equivalent of a 10 metre swell at this scale...

So back to the original question - what weight to get down the hull down to the required level?



What you see here is the hull with 7 2 litre ice cream containers in it. That's, umm, 14 Kgs of water and the hull sunk about 3.5 cm. However it was very unstable with all that water on top of the hull and quite a lot spilled into the hull... I don't know if it was level or not, so it may have sunk further - or less. I'm hoping for the "further" option.

I think, having now emptied most of the water out of the pool, that I need to repeat the procedure and be a little more careful and accurate about the balance and measurements. Initially I was quite happy with the result, but it was done very quickly and probably needs more care and more time to get it right.
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Alister

AlisterL

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Re: ULCC build
« Reply #36 on: October 31, 2009, 09:49:05 PM »

Ahah! I've just read Martin's last post on the "Photo sizes allowed on Mayhem" thread http://www.modelboatmayhem.co.uk/forum/index.php?topic=16854.25 and now I understand why I can't see the link anymore! Going straight to postimage and uploading an image returns a page on completion that allows the resulting url to be copied in bulletin board/forum format - that's the first url in the list...

Anyway, so I filled up the test tank again this morning and had another attempt at getting some good results. On this attempt I took my time, had some assistance and wasn't working against fading light.

First shot is the fore/aft level - I think taken with a 1.353kg (approximately :) 6V 4Ah SLA at the front. The stern is a little heavier than the bow it seems...



The second shot, complete with cheeky monkey, shows the hull with a total of 7.353Kg in it:



And the final image is the hull very carefully balanced with all 7 ice cream containers and the SLA in it, showing the water relative to the waterline - the black dot:



So that's 15.353Kg added in and sitting level. Actually, that will be slightly less than that weight as I didn't fill the containers up to the 2 litre mark as it would have slopped all over the place... So maybe it's 15Kg or so. That's not too bad a level. If the distance about the dot to the top of the hull is 2cm, then with that 15Kg in it the waterline is a bit over 1cm below the dot - the scale waterline - and that could be a good safety margin as I described previously. I figure if I allow for 16Kg of ballast it will be close enough to what I want to achieve.

All I need to do now is figure out how to make it work. I read recently that Uranium has twice the density of lead - some of that could work well. Anyone got any spare..? Probably not... Hah! - maybe this would have to be a bulk carrier if I did put Uranium in :)
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Alister

AlisterL

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Re: ULCC build
« Reply #37 on: November 01, 2009, 02:40:23 AM »

More thoughts about ballasting and batteries:

I need 12V to drive this model with the motor I have chosen. A 12V 7Ah SLA battery has dimensions of 151mm x 100mm x 65mm. My maths says that battery has a volume of about .98 litres. It weighs approximately 2Kg. That's 2.04x the density of water. Not a bad ratio, but the 6V 4Ah I have is about 2.6 times. Either way it makes sense to use that as ballast rather than water.

A quick Google says that lead is 11 x the density of water. That means that for an equivalent weight of each, water will occupy 11 x more volume than lead. Or 19 x more volume than Uranium :) I think this logic is correct - someone tell me if I've got it wrong!

I think that I am aiming for an all up dead weight in the model of around 10 to 12 Kgs and therefore the need to add, either by pumping or free-flooding, or a combination of both, no more than another 6Kgs of ballast as water. If the cube root of 6 is 1.8, then this 6 KG's will require a cube fractionally larger than 18cm x 18cm x 18cm. Again, tell me if I'm on the right track or not.

Also, if I have read and understood other recent posts correctly, I should put my static ballast as across as much of the width of the hull and down as much of the length as possible. But, if I need to combine dynamic ballast, whether free flooded or pumped, then the static should be concentrated fore and aft, with the dynamic in the middle.

I'd love to get some comment on the above...



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Alister

derekwarner

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Re: ULCC build
« Reply #38 on: November 01, 2009, 03:42:10 AM »

Hi Alister.....from the start we should consider the term....."displacement" weight as the criteria  O0

Your trials with ice cream containers of water may not be valid for calculation  .......1 litre of liquid [water] volume = 1 kg ...not sure but is ice cream sold by volume or weight?.... advertizing laws are    %%....may need to fill a said container & proof weigh the actual mass weight which multiples of [+hull & machinary] will =  the vessel total displacement....... Derek  :-))
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nick_75au

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Re: ULCC build
« Reply #39 on: November 01, 2009, 09:17:37 AM »

10 Kgs of lead shot fits in a bag that is about 20 cm x 15 cm x 5 cm or so, or get a roll of roof lead sheet It wont be too fussed about being in water so you can spread it out through the ballast tanks as well.
Nick
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ZZ56

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Re: ULCC build
« Reply #40 on: November 01, 2009, 08:19:34 PM »

Isn't it wonderful to have such a big model?  %)  Just wait till you have "breakables" attached to the hull.

For the water-ballast issue, the only way you could have it act as true ballast is to pump it in and out.  With a free-flooding chamber what you are essentially doing is taking away that much buoyancy from the hull.  It will not affect the waterline much until you start to add weight to it, so don't be disheartened if you put it in the water with free-flooding chambers and find it sits as high as usual.

Now is the time for you to decide if you want the ballast to be removeable or not.  If you do, you'll have to figure out how you will get it in and out. 
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AlisterL

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Re: ULCC build
« Reply #41 on: November 02, 2009, 12:01:30 AM »

Derek - see the attached!



And I measured it as well.

Nick - thank you very much for that info - that is very useful. All I need to do now is find some lead. Although I'm still hanging out for some Uranium... :)

ZZ - Ahh. That's interesting. I assumed that with some lead ballast and a free flooding tank that the ballast would push the model down into the water allowing the tank to flood to the point where it was full. Allowing for, of course, the air to escape... Is that not the case?
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Alister

ZZ56

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Re: ULCC build
« Reply #42 on: November 02, 2009, 01:56:50 AM »

yes, that is how it works.  I meant that with no ballast, the chamber itself won't bring the waterline down by more than a half a centimetre, barely anything. 
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nick_75au

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Re: ULCC build
« Reply #43 on: November 02, 2009, 04:39:26 AM »

yes, that is how it works.  I meant that with no ballast, the chamber itself won't bring the waterline down by more than a half a centimetre, barely anything. 

Would this matter if the overall mass of the model is greater than the un-ballasted displacement,  would it not sink until the remaining buoyancy came into effect?, just the weight of battery's and super structure should be enough?
Nick
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AlisterL

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Re: ULCC build
« Reply #44 on: November 06, 2009, 08:07:00 PM »

Because I could, I used Sketchup to diagram what I my understanding is of  what your suggestions are:



Basically, the lead ballast is at the lowest point (layered sheets) with the dynamic ballast (water) in tanks above it. There are small holes allowing water to flow between each tank and each tank should also have baffles in it (not shown). The air escapes should be a bit smaller than drawn... I haven't shown any method to get the water in or out either.

Do I have it right?
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Alister

AlisterL

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Re: ULCC build
« Reply #45 on: December 11, 2009, 04:52:48 AM »

Wow - my last post was quite a while ago. I didn't realised that it had been so long.

My tasks after my last post was to get some lead - or uranium :) I gave up on the uranium for various reasons and was waiting on a roofer friend to see if I could get some lead sheet. Unfortunately he took his wife off to Fiji for a week which delayed things a bit. In any case, I ended up ringing around a few places and got a 10Kg bag of lead shot. $79 from Reloaders Supplies, in case anyone is interested.



This also solved the ballast question I had with my Zwarte Zee, so I have made some progress on that too.
As a small diversion to the main subject of this thread, I managed to get the deck on the stern of the Zwarte Zee once it was all ballasted correctly, which will allow me to get on with other areas of that build too.



I also put the rest of the superstructure together. Rigging is rather fiddly...



But I got there eventually.

All this ballast available lead (no pun intended) me to progress with sorting out the big boat. I needed to get a 12V SLA to drive the boat, so I ended up with a 12V 9AH SLA that weighs in at 2.560Kg. With this in place I realised that I could probably have a larger dry compartment in the hull and then need to pump water into only two areas - having put three litres of water into a big resealable bag and seeing how it fitted in. The end result is this:



To the left in this image is the stern section with propshaft, motor, rudder etc. There is in this shot a bar-bell weight of 2.5Kg's in the same compartment. I reasoned that, if I needed an all-up weight of 18Kg's in the hull, then that would work out to be 6KG's in each of the three areas in the main rectangular hull. This all leaves me shy of that 6Kg's there by about 400 grams that I can easily make up with lead if I have to. This compartment I have also opened up into the stern section so that I can get access to the pulleys and belt that will drive the boat. By the way the battery and weight are located in place with 14mm thick ply blocks I have glued and screwed into place. The battery and the weight are also removable - meaning that with these two items present just on 5.5Kg's of static weight that I can remove to move the hull around.

Yes there is another bar-bell weight that I am using. Basically I wanted to make sure that I had some lead sitting around after the main static ballast had been put in place for trimming etc. Because I know that I can easily get three litres of water into the remaining compartments I took the opportunity to add some other weight at a cheaper price. This is in the forward section of the rectangular hull:



It is also removable, however, I suspect it will need to become permanently fixed in place as, with a water tank on top and possibly around it, getting to it might be hard!

Next steps:
 - Finish sorting the static ballast
 - Move onto dynamic (water) ballast

Whilst waiting for the roofer to come back from holiday I was busy looking at photos of the superstructure and started framing the opening in the stern section that superstructure will sit on.



I also came a cross a detail (I laugh at myself so much sometimes...) that I had previously missed and that is at the bow, the deck raises up at an angle. I noticed this two ways, firstly in a photo taken from the stern during lightering operations it is clear that the desk at the bow is on a angle and secondly the GA plan I have shows the coaming rising at an angle, but other photos show that the height of the coaming above the deck is a constant. Therefore I have added a section that raises up at the bow.
A view from directly above:



And from the side and slightly above:



Even now the coaming is not complete - it shouldn't extend as far as I have it currently. Partway around the curve of the bow as it comes back from the bow, the coaming disappears down to deck level. The raised section was build using two sections of 7mm ply, the idea being that someday I might want to tow this around and really wanted to be able to anchor some bollards down really well. These two bits of ply are glued and screwed in place.


Anyway, TTFN!

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Alister

AlisterL

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Re: ULCC build
« Reply #46 on: April 23, 2010, 11:31:33 AM »

Hoo boy! 5 months and no progress! Anyone would think I had given up... Well I haven't, but then I haven't done anything on this project either.
The Zwarte Zee has been the centre of attention when I've been doing anything boat-wise.

However, in last post, in the 6th photo, there was the smaller of the two bar-bell weights. What mad logic possessed me to put that in, I have no idea, but it is gone as of tonight. Oh - it was probably the lack of lead sheet! Of course the roofer came back from Fiji and duly supplied a pile of pre-loved lead sheet which I have cleaned up with a wire brush and flattened with a hammer. The result is that this takes place of the lead shot as main ballast - saving the shot for other tasks. This will mean that the two compartments that will have the dynamic ballast will be nice regular shapes and not have any bar-bell protrusions in them.

I'm not expecting to make a lot of progress any time soon as the ZZ is main focus of attention at the moment, but I thought this was worth a short update, if only to show that this is not a forgotten project!

Does anyone know if windscreen washer pumps will be suitable to use for the water ballast? I presume that they can be reversed?
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Re: ULCC build
« Reply #47 on: April 23, 2010, 01:16:24 PM »

AlisterL ...12 volt windscreen washer pumps are manufactured in two varities.....

1. centrifugal impellor style
2. gear on gear pump design

The latter is totally functional in reversable mode.....so for either inlet/outlet = suction/discharge....available in OZ @ K Mart Auto for approx AUD$12.00 ..or the local hobby shop for AUD$24.00

Naturally the hobby shop also has the silicone tubing & the double 8 wire grip clamps to suit  :-)) ... Derek
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AlisterL

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Re: ULCC build
« Reply #48 on: April 24, 2010, 10:52:49 PM »

Derek - brilliant info - thanks very much!
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Re: ULCC build
« Reply #49 on: January 12, 2011, 11:25:40 PM »

Well it has been a long time since I posted on this topic. Almost all that time has been spent waiting to find a solution to the water pump problem. I tried ordering some Graupner pumps from a place in the UK - I think it was Cornwall Model Boats as they were listed as being in stock on the website. Except they weren't and I didn't find that out until the prop I also ordered arrived and the pumps didn't. The prop is a nice Raboesch 5 blader that looks the part. I contacted another UK supplier and was told they were out of stock of pumps too. I tried a local model boat specialist who list Graupner pumps on their website. Quite frankly I was very disappointed by the response - I don't think that they even knew what was on their website and they could not help and didn't even really try. I guess they make heaps of money and don't need my business... Eventually and in desperation I went to an auto parts supplier and found what looked like an appropriate windscreen washer pump. Most non-reversible pumps appear to have a inlet or outlet (not sure which it is) located directly in the middle of the pump housing, in-line with the motor. The pumps I spotted had the inlet and outlet on opposite sides if the housing - that looked promising - so I grabbed one to test. Low and behold, even though there is a arrow imprinted onto the pump housing, they do reverse and they do seem to flow evenly in both directions. Problem solved - so I went a bought another three :) In the course of my testing I discovered that the pumps get quite warm if running for any length of time and knowing that I was going to need to run them for at least a minute I figured I needed to cool them. All this took place before Christmas and I decided that before I actually did anything else I needed to finish of the Zwarte Zee - which from other posts I have made in the last day or two has been done.

My favourite method to cool these pumps was to have them pump that cooling water themselves. I sourced some 1/8" external diameter aluminium tube (I looked for copper but it doesn't seem to be available in 36" lengths at that diameter) and proceeded to make four cooling coils. The way I do this is to crimp one end of the tube with some pliers and then fill it with sand, making sure I tap the tube frequently to get the sand to settle properly. I make use of a funnel to get the sand in easily. With 1/8" tube I was able to do two at once. Once full I crimp the other end of the tube a wrap it around a suitable object. For these pumps a standard 'C' cell was the business.

Some photos of the process:

Coils under construction, not cut, just bent:

Note that one of the tubes (the lower one on the picture) actually broke as I was bending it. I think this was due to not holding the tube tight to the battery and allowing the initial bend to get sharper and go past it's limit.

Two of the coils cut from the leftover tube and awaiting sand removal:


So the process of filling with sand then bending 4 tubes took about 20 minutes. When all were bent I cut off the excess tube and proceeded to empty the sand out. This is a laborious process involving lots of tapping, turning, frustration, cursing, high pressure air, more tapping, boredom and eventually success. I think it took a good 10 minutes to empty each one.
Each coil is then fitted to the pump as shown below:



And that job is done. I then had to figure out final placement and so forth. Given that these will be sitting on lead sheet filling tanks that are on lead sheet I had to finish the lead sheet ballast. I have now got approximately 10Kg's of lead sheet cut and that means my static weight is going to be around the 13 - 14kg mark! The other thing that became apparent is that I need to finish the underside of the hull before fixing the lead in place. So that will be the next piece of work to be done - f/g cloth, epoxy and finishing, including painting (meaning I need to find the colour) to continue.

Watch this space!
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Alister
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