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Closed Cell Buoyancy Foam Test

Posted: Wed Dec 15, 2021 3:43 pm
by Reid
Hello Everyone,

In the interest of science (and also to appease Cape Man :wink: ) I have started a little test on our 2 part Closed Cell Buoyancy Foam (2lb. density). This topic has come up routinely on the Forum so I guess we are long overdue for a test to set the record straight. If a closed cell foam is cut, would it absorb water or would the closely knit cell structure prevent it from absorbing water? Does cutting Buoyancy Foam, as we do when we trim it to fit under our decks and soles, open the cells and allow for the entire piece to take on water?
Cape Man has hypothesized that the amount of water absorbed between two pieces of Buoyancy Foam, one that has not been cut and one that has been cut, will be minimal due to the cell structure of the foam.

The test: I made two identical blocks of Buoyancy Foam. Each one consisted of equal parts A and B (8 mL of each). The foam was allowed to set up with a screw and string in the middle. This was done to allow weight to be attached later on. Once cured, I trimmed the top off one block of foam. Both pieces of foam were then weighed. Weight was then attached to both foam blocks and both blocks were then submerged in a 5 gallon bucket of water. I will leave them submerged for one week, pull them out, and weigh them again. The difference in weight (if any) will show how much water was absorbed. Here are some pictures for your viewing pleasure!

Please feel free to let me know what you think the outcome will be.

-Reid

Start Date: December 15, 2021
Temperature: 78 F
Starting weights: Cut piece = 20 grams, Non Cut piece = 24 grams
Finish Date: December 22, 2021
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Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 15, 2021 3:57 pm
by fallguy1000
Sometimes they use inks for the tests as well.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 15, 2021 4:56 pm
by Jaysen
fallguy1000 wrote: Wed Dec 15, 2021 3:57 pm Sometimes they use inks for the tests as well.
Drop a little blue or red food color in the water. That will show how far the water penetrated.

It would also be interesting to cut along the string to see how much penetration happened along that inclusion.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 15, 2021 9:01 pm
by fallguy1000
My transom steps were setup, by me, as a wet sump. But I realized this area will contact water and constantly be condensating. Also, I can't reach the bottom of it. So, come spring, I am ordering some. I know it needs to be 70 or so to apply.

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 16, 2021 5:41 am
by cape man
Thank you Reid! What a nice Xmas present for all of us! :lol:

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 16, 2021 8:51 am
by Reid
Jaysen wrote: Wed Dec 15, 2021 4:56 pm
fallguy1000 wrote: Wed Dec 15, 2021 3:57 pm Sometimes they use inks for the tests as well.
Drop a little blue or red food color in the water. That will show how far the water penetrated.

It would also be interesting to cut along the string to see how much penetration happened along that inclusion.
Jaysen,

I will see what I can do with the food coloring.
Also, I wouldn't think that the string/screw will have any effect on water intrusion. The reason I say this is because the foam was allowed to set up around the string/screw so technically the cells should be "closed" still. I guess a way to relate this to boat building is when we install chase tubes under a sole and then pour foam around them.
I guess we will have to wait and see.
-Reid

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 16, 2021 8:52 am
by Reid
cape man wrote: Thu Dec 16, 2021 5:41 am Thank you Reid! What a nice Xmas present for all of us! :lol:
Tis the season!!!

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 16, 2021 9:40 am
by Jaysen
I don't disagree. But since we are doing the test we can now semi-empirically prove it. I say "semi-empirically" only because someone will eventually point out that we didn't use lab standards to officially measure.

I think the line may show some capillary seepage. I would expect the same from anything that is encapsulated (chase tubes, bulkheads, etc). It will be interesting to see how far that seepage extends along the surface of the item as well as into the foam.
Reid wrote: Thu Dec 16, 2021 8:51 am
Jaysen wrote: Wed Dec 15, 2021 4:56 pm
fallguy1000 wrote: Wed Dec 15, 2021 3:57 pm Sometimes they use inks for the tests as well.
Drop a little blue or red food color in the water. That will show how far the water penetrated.

It would also be interesting to cut along the string to see how much penetration happened along that inclusion.
Jaysen,

I will see what I can do with the food coloring.
Also, I wouldn't think that the string/screw will have any effect on water intrusion. The reason I say this is because the foam was allowed to set up around the string/screw so technically the cells should be "closed" still. I guess a way to relate this to boat building is when we install chase tubes under a sole and then pour foam around them.
I guess we will have to wait and see.
-Reid

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 16, 2021 3:26 pm
by Reid
Update on the test... Looks the same as I left it yesterday.
IMG_6815.jpg

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 16, 2021 6:26 pm
by OrangeQuest
Shouldn't we get a proper scientific update with a whole weather forecast of the bucket? Like Temp, barometric pressure, and humidity? :roll:

:lol: :lol: :lol:

Re: Closed Cell Buoyancy Foam Test

Posted: Fri Dec 17, 2021 7:27 am
by cape man
Yeah...you won't be able to publish in the Journal of Naval Architecture without that data and at least 3 replicates of the trial. :lol:

But this down and dirty test should at least solve some of the arm chair pontificating on the subject. 8)

Re: Closed Cell Buoyancy Foam Test

Posted: Fri Dec 17, 2021 8:56 am
by OrangeQuest
But this down and dirty test should at least solve some of the arm chair pontificating on the subject. 8)
Never will happen, never ever!

The floatation foam used has already been tested and passed the USCG standards for floatation by marine underwriter laboratory tests.

This test would need to go on forever to prove its ability to displace water for whatever the make-believe standard would be.
This foam has been tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114 . This foam is approximately 95-98% closed cell which resists absorbing water, however continuous water submersion can eventually lead to loss of buoyancy over a period of years.

Re: Closed Cell Buoyancy Foam Test

Posted: Fri Dec 17, 2021 9:02 am
by Reid
OrangeQuest wrote: Thu Dec 16, 2021 6:26 pm Shouldn't we get a proper scientific update with a whole weather forecast of the bucket? Like Temp, barometric pressure, and humidity? :roll:

:lol: :lol: :lol:
Lol. I would but my barometer just broke last week. :lol: :lol: :lol:

Re: Closed Cell Buoyancy Foam Test

Posted: Fri Dec 17, 2021 6:01 pm
by OneWayTraffic
The thing with Foam tests is that you can’t emulate the motion of the boat or the effect of freeze thaw cycles. I’ve got Foam on my boat but it all cases it is installed where water can drain and air can get into ventilate. When foam does absorb water it is generally over a very long period of time so in my case I am assuming that I will be able to keep ahead of it and provide ventilation and inspect all compartments.

Re: Closed Cell Buoyancy Foam Test

Posted: Fri Dec 17, 2021 6:16 pm
by Jaysen
OneWayTraffic wrote: Fri Dec 17, 2021 6:01 pm freeze thaw cycles
say whaaaaat?

We don’t do that in these parts!

Re: Closed Cell Buoyancy Foam Test

Posted: Fri Dec 17, 2021 6:50 pm
by jonnymac
who knows what the UL test actually consists of, they could generate a foam test sample that is something we could never recreate in our home garage.

and that isn’t the question here, the question here is does cut foam behave the same as uncut foam.
OrangeQuest wrote: Fri Dec 17, 2021 8:56 am
The floatation foam used has already been tested and passed the USCG standards for floatation by marine underwriter laboratory tests.

Re: Closed Cell Buoyancy Foam Test

Posted: Sat Dec 18, 2021 10:50 am
by pee wee
jonnymac wrote: Fri Dec 17, 2021 6:50 pm and that isn’t the question here, the question here is does cut foam behave the same as uncut foam.
This! ^

Re: Closed Cell Buoyancy Foam Test

Posted: Sun Dec 19, 2021 6:09 am
by OrangeQuest
who knows what the UL test actually consists of, they could generate a foam test sample that is something we could never recreate in our home garage.

and that isn’t the question here, the question here is does cut foam behave the same as uncut foam.


https://www.document-center.com/standar ... ASTM-D2842

I believe you can see where it goes over damaged cells as well. For the complete standard of tests, you can spend $54.00 and let the rest of us know.

Then you would apply these standards to test per the Fed gov regulations on floatation use in boats. And different types of foam can be used in different areas of the boat.
Like I stated, the floatation foams we buy and sold as floatation foam have passed testing.

Re: Closed Cell Buoyancy Foam Test

Posted: Sun Dec 19, 2021 6:41 am
by cape man
I'll wait for Reid's results before responding... 8) :lol:

Re: Closed Cell Buoyancy Foam Test

Posted: Sun Dec 19, 2021 6:52 am
by jonnymac
thanks for posting that. the scope of the test. shows that this test covers how well does the foam maintain buoyancy in a short term single event situation. which is important, but It seems to me that the question most builders have. Is the cut cells going to increase water absorption overtime.
This test method covers the determination of the water absorption of rigid cellular plastics by measuring the change in buoyant force resulting from immersion under a 5.1-cm (2-in.) head of water for the specified immersion period of 96 h.
OrangeQuest wrote: Sun Dec 19, 2021 6:09 am
who knows what the UL test actually consists of, they could generate a foam test sample that is something we could never recreate in our home garage.

and that isn’t the question here, the question here is does cut foam behave the same as uncut foam.


https://www.document-center.com/standar ... ASTM-D2842

I believe you can see where it goes over damaged cells as well. For the complete standard of tests, you can spend $54.00 and let the rest of us know.

Then you would apply these standards to test per the Fed gov regulations on floatation use in boats. And different types of foam can be used in different areas of the boat.
Like I stated, the floatation foams we buy and sold as floatation foam have passed testing.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 1:15 pm
by Reid
Well the results are in and, I must say, I am left with more questions than answers.
Here are the results:
Non Cut piece: Starting weight 24 grams, ending weight 74 grams (208% increase in weight)
Cut piece: Starting weight 20 grams, ending weight 64 grams (220% increase in weight)

So I must admit, I did not expect these results. However, there may be some variables that could have negatively impacted the results of this test.
1) As Jaysen pointed out (and I didn't agree with), the string that was attached to the screw may have given the water a pathway into the middle of the piece of foam.
2) The foam was mixed in a plastic mixing cup and then pulled out of the cup once it was cured. The bottoms of both foam samples were not as smooth as the tops. This could have been due to being pulled from the cup.
Could this have given the water a pathway to enter the foam as well?

To confirm the water intrusion I cut each piece in half. I blotted the inside with a paper towel and then squeezed one half in a vice. Both paper towels were wet and both pieces that were placed in the vice produced puddles of water.

I think this test might have to be re-run to eliminate the variables. Maybe leave the foam in the mixing cup and simply weigh it down by placing something on top of the foam. This would eliminate the string in the middle.

As with any scientific experiment these results will be open to your comments, scrutiny, and constructive criticism.

Here are the photos of the results:
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Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 1:38 pm
by piperdown
I wonder if a full 7 day cure might make a difference.... :doh:
I agree that there had to be some capillary effect using string. Wonder if something like weedwacker line (nylon, assuming it wouldn't melt) might not be a better choice.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 1:42 pm
by Reid
piperdown wrote: Wed Dec 22, 2021 1:38 pm I wonder if a full 7 day cure might make a difference.... :doh:
I agree that there had to be some capillary effect using string. Wonder if something like weedwacker line (nylon, assuming it wouldn't melt) might not be a better choice.
It actually was a nylon string.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 2:05 pm
by OneWayTraffic
I'm assuming that the foam was mixed in ideal conditions? I'm a little surprised that water was absorbed, but not shocked. There are multiple documented cases of water getting into foam, in for example old whalers. Google 'chainsaw whaler' for an interesting thread. On the other hand some identical boats never get water in the foam despite years of neglect. There is also this guy Ike on Hull truth and Boat design that used to work for the coast guard. He's a mine of information.

https://www.boatdesign.net/threads/hull ... ion.13679/

Seems to me that the upshot is that one should take great care in measuring and mixing two part foam. Temperature needs to be right. Best is to get block foam made in a factory and cut to shape. I can attest that the block foam I bought is higher quality than what I mixed myself despite the two using the same ingredients from the same supplier. Also important is that if a compartment has foam in it, it either be fully sealed or be kept ventilated.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 2:21 pm
by silentneko
I think the cure time might be the biggest issue here. Properly cured closed cell foam should not absorb moisture like a sponge. Water should only be able to penetrate the exposed cells, not wick its way through the structure.
I've done similar tests with an other 2lbs foam and great stuff from Home Depot. Neither absorbed much after a few days.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 4:26 pm
by Dan_Smullen
Reid, Science and the Community thank you.

If you run the experiment again you could devise a way to determine if the foam will shed the water it absorbs. Seems like it would due to gravity alone. :doh:

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 5:00 pm
by fallguy1000
Reid..

Any good test needs a control.

What would a control be?

Something that should show zero change. For example, a piece of foam encapsulated in epoxy.

Also, I have an issue with the size of the sample. Despite it being a massive pain in the rear, I'd want to test a larger piece.

Surface area. The surface area is a factor; not simply the weight. The absorption is measured against area, no? So, if your cups are say 3" cylinders; the area is 42.4 square inches and the absorption is say 46 grams in 42.4 sqin. For a 7' wide boat by 16' long, themat is 16,128 sq inches which results in 17500 grams which is ?36 pounds of uptake for an entire boat surface one side (assumes other side is not accessible by water).

Consider my remarks conversational.

Oops. Remarkably more math errors..

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 5:02 pm
by fallguy1000
Of course, this is why the ink tests are done, because they want to know if it keeps going beyond the surface much...

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 6:30 pm
by OrangeQuest
Thank you, Reid, for taking the time and using the resources to conduct this test.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 6:36 pm
by fallguy1000
See my math edits... ugh... I am having a bad day..

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Dec 22, 2021 9:29 pm
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.

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 2:40 am
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.

Tom

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 8:31 am
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.

"If we knew what we were doing, they would not call it research."

Albert Einstein

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 11:52 am
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.

-Reid

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 11:58 am
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.

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 12:41 pm
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.

-Reid

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 12:56 pm
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?

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 3:20 pm
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... :)

Re: Closed Cell Buoyancy Foam Test

Posted: Thu Dec 23, 2021 6:56 pm
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

Re: Closed Cell Buoyancy Foam Test

Posted: Fri Dec 24, 2021 6:10 am
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.

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Jan 25, 2023 9:07 pm
by millerboys
Try this with eps foam. Way better results

Re: Closed Cell Buoyancy Foam Test

Posted: Wed Jan 25, 2023 9:25 pm
by fallguy1000
millerboys wrote: Wed Jan 25, 2023 9:07 pm Try this with eps foam. Way better results
Can you pour it?