Building with Craft Foamboard

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Building with Craft Foamboard

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19 March 2013 at 15:32 #6870
Paul T
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@pault84577
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19 March 2013 at 15:32 #39780
Paul T
Participant
@pault84577
After recent discussions regarding building with craft foamboard I decided to build a 5ft River cruiser to test out the construction theory of laminating foamboard sections together for increased strength.

I designed the river cruiser a couple of years ago but never got around to building a full size version.

View of frame showing laminated keel

View of frame from below rear cabin

View of rear cabin roof

Paul

Edited By Paul T on 19/03/2013 15:38:03
19 March 2013 at 17:40 #39783
ashley needham
Participant
@ashleyneedham69188
Paul. Interesting, should be very light! This is going to be electric do we presume?

Ashley.

nb..nice bit of Wilton carpet in your plush workshop.

Edited By ashley needham on 19/03/2013 17:43:06
19 March 2013 at 18:28 #39784
Paul T
Participant
@pault84577
Ashley

Yes its so light I can pick it up with one finger, as for the engine I think a shaver motor should do the trick.

Its to cold in the workshop so I'm working in the garage.

Paul
20 March 2013 at 10:51 #39792
Kimosubby Shipyards
Participant
@kimosubbyshipyards
Hello Paul,

Yes very interesting and economical too. A couple of questions if I may,

what adhesive do you use?

what is your main cutting tool?

I've looked for something like this for Club show days to get the younger ones interested in making their own boat, on the day, with guidance and using pre drawn templates, and seeing it float away too.

Kim
20 March 2013 at 11:08 #39793
Paul T
Participant
@pault84577
Hi Kim

Adhesives are UHU / 151 solvent for the reinforcing card at the joints and waterproof PVA for the laminations. Only cutting tool is a Stanley knife with fresh (sharp blades).

The foamboard joints are reinforced with 300gsm card because the solvent glues melt the boards foam core.

Cutting and building is fast and the boards can be curved by slicing shallow easing cuts into one side.

Easing cuts on the inside of a cabin roof, note the card reinforcing angles connecting the ribs to the roof.

Paul

How's life on the rock, are you still coming over on the vomit bucket on Thursday

Edited By Paul T on 20/03/2013 11:27:44
20 March 2013 at 15:52 #39796
Kimosubby Shipyards
Participant
@kimosubbyshipyards
Ah, you've seen the forecast then.

On the Ben coming to you, but on the "Vomi….B….." from L'pool Monday evening weather depending!

I'll try some of the board, our local model shop down the road stocks it. Locate some simple plans and see what I can do. May have to enquire with Ashley for his rubber band drive force too.

Kim
20 March 2013 at 18:32 #39798
Paul T
Participant
@pault84577
Hi Kim

The Ben is bad enough, It had just been bought the last time I went on it (before they filled it with concrete) and it bobbed around like a cork in a washing machine, give me the old King in a force 8 any day.

Paul
20 March 2013 at 20:12 #39800
Kimosubby Shipyards
Participant
@kimosubbyshipyards
Aye, the King Orry was a good 'un, I did a force 10 in her one night for 8 hours coming home from Heysham about Christmas time, but my record was an outstanding trip (in more ways than one) on the old Ben-My-Chree side loader, 16 hours plus, Liverpool to Douglas, passing Peel 3 times. She ran out of tea after 8 hours and eventually the crew took pity and "rented" cabin space to those who could offer donations.

I think it was about 1978 as the next bad one I remember I went out to the Ben on Peel LB to take Sunday papers, I had been invited to exercise with them that Sunday.

Those were the days, Kim
22 March 2013 at 15:35 #39837
Paul T
Participant
@pault84577
Kim

I used to enjoy sailing in the King as it felt like a proper ship rather than a glorified ferry and spent many happy hours in the bar during heavy storms watching the wind and waves crashing outside and the unfortunate seasick crashing around on the inside, had to avoid the toilets though as they were usually awash before we got out of the Liverpool channel.

16 hours from Liverpool to Douglas must be a record but why pass Peel so many times? or was it a case of any port in a storm and circling the island until a port opened.

Paul
22 March 2013 at 15:42 #39838
Paul T
Participant
@pault84577
Back to building with foamboard.

I have started to fix the skin onto the frames and whilst the straight bits are easy the curves at the bow have been a problem.

I started fitting narrow vertical boards in order to overcome the problem of getting the rigid foamboard around the double curves but after some experimentation I found that by scoring a 3mm deep diamond pattern in the rear of the 5mm boards they would become far more workable and enable a certain degree of flexibility when doing the compound curves.

I will post some photos when I get the camera back.

Paul
24 March 2013 at 13:53 #39880
Paul T
Participant
@pault84577
You can see where I started to fit the boards before I discovered the diamond scoring technique.

To be honest I was starting to worry about getting these almost rigid planks to follow the simple curves of the bow and even though this side hasn't turned out as well as it could have the experience has been invaluable (a bit of filler will sort this bit out)

The other side should go on a lot neater.

Total weight so far is just under 2lbs

Paul
25 March 2013 at 07:59 #39888
ashley needham
Participant
@ashleyneedham69188
Paul, what filler are you going to use and is the foamboard rigid enough for filler without flexing? Are you going to ez-cote this and and and

Something mixed with PVA might do, improve adhesion on what is basically a card model?

Ashley
25 March 2013 at 09:20 #39891
Paul T
Participant
@pault84577
Hello Ashley

I'm using a 151 decorators filler, it comes in a cartridge and is gun applied (and £1 a tube) the boards flexibility isn't an issue as the filler grips very well.

I could have used PVA mixed with sawdust but that would be more expensive.

After rubbing down, taking care not to abrade the surface of the boards, I will be applying a layer of PVA soaked paper dust sheet to achieve a rigid and stronger hull in much the same way as using tissue on balsa strengthens a balsa hull.

What I don't know is wether or not the hull will then be strong enough to withstand impact damage but a simple test involving dropping a weight onto the hull will soon sort that out.

Paul
25 March 2013 at 09:28 #39892
ashley needham
Participant
@ashleyneedham69188
Paul, I think that, if you dont need to ballast too much,and the boat remains as light as it can be, then the impact resistance should be ok due to the low mass inertia of the thing. Several of mine are very light and almost bounce off hard objects that mysteriously get in the way (how do they do that??)

I think that PVA is often looked over as a method of strengthening stuff, I use it a lot, and your final covering of paper/PVA should be well tough enough.

Ashley
25 March 2013 at 18:49 #39898
Paul T
Participant
@pault84577
Ashley

PVA is superb for strengthening materials as long as it is used in conjunction with paper or cloth.

The model still has to withstand a 10kg impact (weight dropped from 2m)

Paul
25 March 2013 at 22:38 #39907
ashley needham
Participant
@ashleyneedham69188
oo er, rather you than me with that one.. is this your standard practice or are you ensuring that the boat, as it is using a novel building method, is up to the job? Ashley
26 March 2013 at 11:15 #39911
Paul T
Participant
@pault84577
Ashley

I have to test the theory that the model will withstand the impact of another speeding large model e.g. a Sea Queen moving at 12 – 15mph. Hence the dropping weight test.

Paul
26 March 2013 at 19:59 #39922
Paul T
Participant
@pault84577
Packing the spaces between the hull and the inner frame with polystyrene will help withstand and spread the load of any side impacts.

It also adds the one thing that this model doesn't need……. extra buoyancy.
26 March 2013 at 21:42 #39926
ashley needham
Participant
@ashleyneedham69188
Paul. Will you be running into stability issues with the hull being as light as it is?? ie I was thinking of being able to sit the various weights low enough.

I know you will not need a lot of power (what a silly thing to say), but a heavy motor would probably be just as well, to get some weight low down. An 850 or something !!! yeah baby.

Are you expecting full on combat in your sailing area?

Ashley
27 March 2013 at 08:04 #39931
Paul T
Participant
@pault84577
Ashley

There will be stability problems even for this semi planing hull but in addition to having removable motor and battery pods I intend to install pumped ballast tanks in the bilges.

The combination of these two measurers will have the double advantage of stability when afloat and keeping the carriage weight down as the motors and batteries are carried separately and the tanks filled when the model is actually on the water.

Whilst I am not expecting the model to enter combat zones it does have to be fit for purpose after all its no good my pontificating about this method of building if the resulting model cant withstand being dropped on the floor or a mishap with a fellow boater.

Paul
30 March 2013 at 13:15 #39989
ashley needham
Participant
@ashleyneedham69188
I have contemplated tanks on several of mine, I would probably just make them free flooding, though. The only draw back with this is the draining on removing from the water, as obviously the boat is as heavy as it is until the ballast water has been drained and for that you need to lift it up.. I suppose large vents would make this easier, the water would exit reasonably quickly and so the boat could be lifted out by degrees in a minute or so?

The only other think is getting the tanks in the right position and of the correct capacity. Would you baffle these tanks to stop slopping??

Every pond needs a slipway really, then you could have a little wheeled dolly and just drive the boat on to it and wheel it out of the water and wait for the tanks to drain!

Ashley
30 March 2013 at 15:22 #39993
Ian Gardner
Participant
@iangardner62867
I think Paul mentioned that the tanks would be pumped. Just as well too- I had a 16 foot day boat with water ballast tanks and she was lovely going into the water off the trailer, but a real handful coming back up against gravity with tanks full. I eventually swapped the water for sandbags.

Very interesting looking boat Paul – look forward to seeing how she comes along. Any idea of final displacement?

Ian
30 March 2013 at 17:19 #39994
Kimosubby Shipyards
Participant
@kimosubbyshipyards
Hi Paul and Ashley,

You mentioned a slipway Ashley, we've gone the other route as we cannot have a slipway in a mill pond – we've got permission to instal a hoist, one of those that is used to lift electric chairs in and out of car boots, on the concrete bank. Maximum lift is 75Kg.

We'll design a sling system so any and all large boats can be launched/recovered. Using a cantilever forklift we can handle most keel types.

Sorry Paul, a bit away from fibre board, Kim

PS these hoists are very cheap second hand on that well known selling site!
30 March 2013 at 17:40 #39995
ashley needham
Participant
@ashleyneedham69188
Kim. We are not quite at the "needing heavy lifting equipment" stage, not just yet anyway. A sling and two people is a much as we have needed so far..but then I am young and viggerus..who knows when I get to Pauls age I may well have to convert everything to pumped water ballast.

I did see a picture of a very neat self contained electric lifting system..cant remember where though now..just a frame that sat over the waters edge and it had a gel battery for power. When the time comes, or I build that bigger model I will have to get the Mig welder out!

I have only actually seen one pumped ballast system at the pond, and this was a very large landing craft. It needed, as you can imagine, a lot of water to be pumped inboard and the little "fire hose" type pump took ages, and we were all for holding it under, it was so slow.

I think that discussion of launching and recovery is quite valid for any build, especially one using unusual materials, such as foam reinforced card. It is no good building something if it sags when lifted or is too heavy/delicate/wide/whatever to launch.

I had been looking forward to a bit of boating action tomorrow… but as I am typing this, the sky has gone a really really really dark grey…. doesnt bode well for tomorrow!

Ashley
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