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Author Topic: Foam type for buoyancy  (Read 1875 times)

terry1956

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Foam type for buoyancy
« on: May 29, 2021, 11:08:45 am »

Well I am at the stage I need too add some buoyancy to the hull. So question is, what’s the best type to use. The only high density foam I know of is kingspan insulation foam. Are there any others available in the uk. Thanks.
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john44

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Re: Foam type for buoyancy
« Reply #1 on: May 29, 2021, 01:31:48 pm »

I use kiddies swim noodles. Various diameters and lengths.


John
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Martin [Admin]

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Re: Foam type for buoyancy
« Reply #2 on: May 29, 2021, 03:15:14 pm »


Builders insulation foam is OK but needs a LOT of room to expand and vent .... may take over a week to fully cure!


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Car wash !!!

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Re: Foam type for buoyancy
« Reply #3 on: May 29, 2021, 03:32:14 pm »

I use ping pong balls and bubble wrap
works for me :-) :-))
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Martin [Admin]

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Re: Foam type for buoyancy
« Reply #4 on: May 29, 2021, 04:10:55 pm »


Oh yes, bubble wrap, very cheap, convenient, ubiquitous.  :-))
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Andyn

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Re: Foam type for buoyancy
« Reply #5 on: May 29, 2021, 04:48:23 pm »

Pipe lagging :-))
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Tug Fanatic

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Re: Foam type for buoyancy
« Reply #6 on: May 29, 2021, 05:01:33 pm »


Builders insulation foam is OK but needs a LOT of room to expand and vent .... may take over a week to fully cure!


Martin.

I am not sure what "builders insulation foam" is but if you mean the expanding stuff that comes in a spray can I wouldn't go there. The stuff that I cut out doing a repair had absorbed water which meant that it was heavy & not very buoyant.   
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terry1956

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Re: Foam type for buoyancy
« Reply #7 on: May 29, 2021, 05:38:29 pm »

Thanks chaps
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phillnjack3

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Re: Foam type for buoyancy
« Reply #8 on: May 29, 2021, 07:29:16 pm »

pool noodles are ideal. you can cut them and still they dont hold water. 2 part foam is no good at all if the skin gets broken, it will trap water and will never release it unless you squash it to get it out...


pound shop often has the pool noodles 2 for a pound.....
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RST

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Re: Foam type for buoyancy
« Reply #9 on: May 29, 2021, 08:34:10 pm »

Given the OP's question he might want something he can more carefully know the volume and is reasonably rigid, even under very low pressure. I don't know myself for a submarine but kingspan XPS or even small blocks of EPS from packaging might be OK.  I'd imagine bubble wrap or expanding polyurethane foam will trap some water somewhere which might not help much.  Plus the usual tinternet warnings on expanding polyurethane building insulation foams, it gasses off and can expand for ages after.
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Subculture

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Re: Foam type for buoyancy
« Reply #10 on: May 29, 2021, 10:39:18 pm »

Closed cell foam polystyrene, usually pigmented blue, but can come in other hues.

Can be carved and shaped to suit the contours. Ebay, EMA model supplies etc. Builders merchants unlikely to stock it, they tend to stock polyurethanes foam which is often partially filled glass and has other issues making it less suitable for this purpose.
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terry1956

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Re: Foam type for buoyancy
« Reply #11 on: June 05, 2021, 01:45:24 pm »

Well today, I think I got the trim and buoyancy correct. The bow is a bit up but that will be better when the battery position is moved a bit forward. Buoyancy obtained by a mix of kingspan foam and pool noodles in the bow section.
So a little bit more work on the WTC bulkhead fittings and when the 3d printer completes the servo mountings, I will be set to go. Thank you for your help.
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