Got a question on "foam"

leesumm · Jan 22, 2013

I am in the middle rebuilding a 15 foot trihull "magnum" brand open bow. I have the top off and the hull cleaned with new stringers in now ready to pattern and cut the floor. I was going to order the foam that mix in two parts and pour in the floor for sound and added insulation. I noticed at Walmart they have areasol cans of foam. The description says its a closed cell expanding foam for insulation and sealing voids. Is this the same stuff as the pour two part foam? I am guessing that it would take maybe 4 or 5 cans @ $3.99 compared to $50.00 for the pour foam plus shipping. Can it be used in place of ? Sounds like I am trying to cut corners and be cheap but just trying to save some money. This is available and I would have to order the other stuff and wait.

Teamster · Jan 22, 2013

Re: Got a question on "foam"

I've never seen anything in a can that is truly closed cell,.......

Even if it was I doubt you would get the volume you need out of 4 or 5 cans,...

jigngrub · Jan 22, 2013

Re: Got a question on "foam"

You overestimate the quantity of foam in those cans, it'll probably take 25 cans or more to foam your boat. The 2 part mix is much cheaper than the canned foam.

Have you figured how many cubic feet of the 2 part it will take to fill your below deck?

tpenfield · Jan 22, 2013

Re: Got a question on "foam"

The spray can urethane foams are great for using as an adhesive and maybe filling a few gaps here and there, but no match for the needs of flotation/structural foam in boats.

once you use the 2-part mix foam, you will see that it is quite different than the insulating foam that you buy at home improvement centers, etc.

jbcurt00 · Jan 22, 2013

Re: Got a question on "foam"

The pour in foam will also do a much better job of SIGNIFICANTLY filling the hull w/ foam.

leesumm · Jan 22, 2013

Re: Got a question on "foam"

ok, I wasn't sure , but thanks for the info. I noticed that there is two different foams in the cans. One for close small fills and another for big fills. I read the descriptions and looked the manuf. on the net all claim to be "closed cell" I don't really know how to estimate the "volume" I will need , only that the space will be about 8 inches deep at the deepest graduating to 0 clearance on the side. The width is about 55 inches and length of the main beam is about 9.5 feet . So I am not that good with math to figure that cavity. Only to pour and see

jigngrub · Jan 22, 2013

Re: Got a question on "foam"

leesumm said:
ok, I wasn't sure , but thanks for the info. I noticed that there is two different foams in the cans. One for close small fills and another for big fills. I read the descriptions and looked the manuf. on the net all claim to be "closed cell" I don't really know how to estimate the "volume" I will need , only that the space will be about 8 inches deep at the deepest graduating to 0 clearance on the side. The width is about 55 inches and length of the main beam is about 9.5 feet . So I am not that good with math to figure that cavity. Only to pour and see

I understand about the math thing. Figuring cubic feet (concrete) is part of my job, and I do it a lot.

By your measurements you will need 14.29 cubic feet of foam to fill that void... that is if you pour at the optimum temperature for expansion which is 80*F or above. If you pour in cooler temperatures you will need more foam because it doesn't expand as much at temps below 80*.

I'd order (2) 16 lb. kits (8 cubic feet each) from here:
Urethane Foam , Expanding Marine Polyurethane Foam

They have fast shipping and great service.

jbcurt00 · Jan 22, 2013

Re: Got a question on "foam"

This may help calculate cubic volume, but you need to convert everything to inches or feet....\

And showing the work:

If you make the assumption that you are filling a rectangular area (half from centerline to port and again centerline to starboard, combined to make a rectangle/square):

Using the above online calculator & your dimensions (27.5" wide(1/2 the total beam) by 8" deep at the keel by 114" long) {converted all to feet: 2.3X0.66667X9.5} I got 14.6+/- cubic feet. So it confirms that my 'rectangle' estimate is very close and Jig's recommended 2 kits is spot on too....

On a fairly low profile tri-hull, the above method would be less accurate...
Probably work fairly good on this type of semi/deep Vee hull shape:

But not on this 'tri-hull':

tpenfield · Jan 22, 2013

Re: Got a question on "foam"

One thing that I have found with the 2-part foam kits is that you do not get the full volume of foam, unless you are working with it at a fairly high temperature (80-90 F degrees).

I concur with the math of about 14 cubic feet, so you might be OK with 2 kits of 8 cubic feet each.

If you are working in colder temperatures (60-70 F) . . . maybe you want more like a kit(s) totalling 20 cubic feet.

jigngrub · Jan 22, 2013

Re: Got a question on "foam"

jbcurt00 said:
Using the above online calculator & your dimensions (27.5" wide(1/2 the total beam) by 8" deep at the keel by 114" long) {converted all to feet: 2.3X0.66667X9.5} I got 14.6+/- cubic feet. So it confirms that my 'rectangle' estimate is very close and Jig's recommended 2 kits is spot on too....

I was wondering if someone was going to check my math... should'a figured it would be you.:laugh:

I didn't use the calculator and just figured it like I would a concrete pour, I figured half the width and 8" depth and the total length then multiplied by 2 and came up with the 14.3... then after I posted I figured it with the rectangle method and came up with 14.51. I'm sure the difference is because I figured 4" @ .33' and 8" @ .67'... that extra .01 will getcha every time, amazing at how much an extra 1/8" will change stuff like that.

... but thanks for checking me, I coulda messed up... I've done it before.:facepalm:

jbcurt00 · Jan 22, 2013

Re: Got a question on "foam"

I wasn't really checking you... It was more about the showing your work. Ya know the whole give a man a fish VS teaching a man :blah:

leesumm · Jan 22, 2013

Re: Got a question on "foam"

ok, thanks guys , its about as clear as mud to me but I get the idea. Never was good with math . 1 +1 always = 3 to me LOL

jigngrub · Jan 22, 2013

Re: Got a question on "foam"

So, did a little research to see if I could find out just how much foam is in a can of great stuff... of course they didn't make it easy for me by telling me how much of a cubic foot was in a 12 oz. can. Instead they said that 1 12 oz. can would produce a 3/8"-1/2" bead 250 long. I figured this as a round bead 7/16" in diameter and 250' long and came up with .176 cu. ft. per can... and 14.29 cu ft. divided by .176 = 81 cans to fill lees boat. @ $4 a can that's $324.

The price for (2) 8 cu. ft. kits of foam shipped from USComposites is about $160.

jbcurt00 · Jan 22, 2013

Re: Got a question on "foam"

What's the time on trigger to shoot 80+ cans of GS?
An hour 20 +/-??

And how many friends do you need shaking 2 at a time to get all 0.176cu ft out of each can?
10 shaking them in round robin fashion? :frown-new:

That's a whole lotta shakin' going on............

1FASTLASER · Jan 23, 2013

Re: Got a question on "foam"

jbcurt00 said:
What's the time on trigger to shoot 80+ cans of GS?
An 1:20 +/-??

And how many friends do you need shaking 2 at a time to get all 0.176cu ft out of each can?
10 shaking them in round robin fashion? :frown-new:

That's a whole lotta shakin' going on............

Man I tell you. Gotta love this forum. Needed a laugh an here it is

leesumm · Jan 24, 2013

Re: Got a question on "foam"

Amazing!!!!. I thought it was a simple question of curiousity when I asked. Never thought it would open a can of worms.

JASinIL2006 · Jan 24, 2013

Re: Got a question on "foam"

leesumm said:
Amazing!!!!. I thought it was a simple question of curiousity when I asked. Never thought it would open a can of worms.

This is nothing! Ask a question about gasoline stabilizing additives or which gear lube oil you should use, and you'll set off of a true conflagration! ;-)

Jim

Got a question on "foam"

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