Closed Cell Buoyancy Foam Test

Post any and all methods for doing things here, if you think you have a good method, that you don't see most builders using
Fuzz
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Re: Closed Cell Buoyancy Foam Test

Post by Fuzz »

What you saw with the foam is why if I ever build another boat like these I will do things a little different. I still want foam in the boat but I want it up high under the gunwales. Much less chance of it getting wet plus if it is ever needed it is in the right spot to keep the boat upright. It does not matter much if the boat floats upside down and you can not use it to get out of the water, at least if you boat where the water temps are like ours in Alaska.



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Re: Closed Cell Buoyancy Foam Test

Post by TomW1 »

Reid a couple of hypothethesis to throw at you. !. Since the foam in a boat is encased in epoxied wood, with only the top cut off and then sealed on top should you not duplicate these conditions. 2. If not let the foam cure for a week to dpliicate the time it has to curing time on a boat before it is sealed up.

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Re: Closed Cell Buoyancy Foam Test

Post by cape man »

Well that was interesting... Thanks for running that down and dirty trial Reid. I am out off and on until February (two separate trips to Cape Sable planned for January!), but when I get back I may run a trial here at work that has replicates and controls.

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Re: Closed Cell Buoyancy Foam Test

Post by Reid »

TomW1 wrote: Thu Dec 23, 2021 2:40 am Reid a couple of hypothethesis to throw at you. !. Since the foam in a boat is encased in epoxied wood, with only the top cut off and then sealed on top should you not duplicate these conditions. 2. If not let the foam cure for a week to dpliicate the time it has to curing time on a boat before it is sealed up.

Tom
Tom,

That is exactly what I was thinking for the next test.
I thought about constructing three boxes made from marine ply and lined with fiberglass. Foam would be poured in all boxes. Two would be trimmed/cut flush with the sides of the box (similar setup for foaming under a sole) and one left alone. One of the cut samples would be coated with epoxy (as Fallguy suggested), this would serve as a control or even a further evaluation to see if coating with epoxy works to prevent water intrusion. I think a 7 day post cure is a good idea as well. The boxes would then be submerged in water for a length of time. We could even add food coloring to track the water intrusion.

I certainly don't want to go too overboard but if anyone has any further suggestions on the next experiment please share. Maybe I can get started next week.

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Re: Closed Cell Buoyancy Foam Test

Post by Jaysen »

Skip the glass/ply box. Just use the plastic cup. That will ensure the waterproof container. It will also eliminate and defects in the box construction.
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Re: Closed Cell Buoyancy Foam Test

Post by Reid »

Jaysen wrote: Thu Dec 23, 2021 11:58 am Skip the glass/ply box. Just use the plastic cup. That will ensure the waterproof container. It will also eliminate and defects in the box construction.
Jaysen,

Are you suggesting that I would have defects in my fiberglass box construction? :lol:
Just kidding, I will take that under advisement for the next test.

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Re: Closed Cell Buoyancy Foam Test

Post by Jaysen »

Of course not! But the method would silence those that look for points of variation between tests. People like me!

That and it would save you a couple days of waiting for epoxy to cure. We are an impatient lot aren’t we?
My already completed 'Lil Bit'. A Martens Goosen V12 set up to sail me to the fishing holes.
Currently working on making a Helms 24 our coastal cruiser.
“Mark Twain/Samuel Clemens” wrote:Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day.
Jaysen wrote: Mon Apr 29, 2019 3:44 pm I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

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Re: Closed Cell Buoyancy Foam Test

Post by fallguy1000 »

I think the main thing is to remember is surface area.

So, I would try to make varied sizes (a bit) and then determine an absorption rate. # or oz/sq in? You can use any approach.

I'm also awfully curious if you have any change in the cups now after a few days.

And, when you measure low weight items; you ought to use a dummy. Not, not me. But something of a known and consistent mass, say like a can of soup from the pantry that you know weighs 600g. This will eliminate scale errors which I find to be all to common in weights below 50 grams.

And, despite the numbers; for absorption; you really need to dry the samples for about 12-24 hours because it could all be surface water which isn't the goal.

Anyhow, I really think the testing is a cool idea and a bit saddened by the numbers as well.

Also, for semantics, show the weights from the start.

And, using my example of 3" cylinder; here is something else for you.

21.21 cubic inches.

21.21 cuin/1728 cuin/cuft is 0.01227 (sig fig issues) cuft

Time 2#/cuft foam is 0.0245# * 454 grams is 11.14 grams.

If you used 4# pour foam; then that would explain start weights being double or I could be off on 3" guesses.

But you ought to post the calculated weights as well. Not to make it more complex, but for sanity checking.

Got none here... :)
My boat build is here -------->

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Re: Closed Cell Buoyancy Foam Test

Post by TomW1 »

Reid you are on the tight track. Just make sure you pour the same amount of foam in each box. Make this as close to real conditions as you can the 3rd box can have a little less so the foam does not over flow the top. Merry Christmas to you and your family.

Tom
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Re: Closed Cell Buoyancy Foam Test

Post by cape man »

I would use 15 red solo cups and leave the foam in. Fill them with equal amounts of foam to an inch below the lip. Cut the top of the foam off of 6 of them. Let cure for 7 days and weigh each cup. Fill 3 cut and 3 uncut cups with water and let sit for 7 days (hole or leak in the deck). Poke a hole in the bottom of 3 cut and 3 uncut cups and place them in an inch of water for 7 days (hole or leak in the hull). Add water to keep the cups full and a constant inch of depth for those with holes in the bottom. This will compensate for evaporation and if the foam is absorbing water will see how much it will over a week of exposure. The remaining 3 are your controls which you just store nearby.
Add food coloring to the water in the beginning. After a week dry the cups with a towel and pour the water out of the cups you filled. Compare pre and post weights. Cut the cups in half vertically and observe dye intrusion.

As to scale accuracy you can weigh each cup 3 times. If there's variations you will see it. If the scale is simply not calibrated it shouldn't matter as the error up or down will be consistent with all the cups.
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