Bad Mix of Foam?

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BB Sig
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Bad Mix of Foam?

Post by BB Sig » Fri Mar 08, 2019 8:42 pm

I am guessing that when foam shrinks, I mixed it wrong. The foam in this compartment actually shrank after it cured. It completely pulled away from the stringer. :help:

Image

My inclination is to pull it out and re-pour the compartment. Can anyone confirm this is the right decision? :doh:

Option two is to just pour new foam in the gap which is less work but doesn't seem right. :roll:



Jwhitakeriii
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Re: Bad Mix of Foam?

Post by Jwhitakeriii » Fri Mar 08, 2019 8:51 pm

Following. I have no advice on this one

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Re: Bad Mix of Foam?

Post by fallguy1000 » Fri Mar 08, 2019 8:59 pm

I am guessing a temperature variation. Think the boat is 70F. And the foam is 60F.

The foam hits the boat and warms and expands.

Or, conversely, the boat is cold. And the foam is warmer or warms on reaction....when the foam cools to ambient; it would shrink. And this is what I see.

Cold boat.

Cut it off rough and foam above it. I think the foam just cooled.

You should have some idea as to how close your volumes came out. The only way I pull it is if the volumes are way off or the boat was super cold.

All a hunch.

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Re: Bad Mix of Foam?

Post by Fuzz » Fri Mar 08, 2019 10:08 pm

Is the foam as solid as the rest of it? Pretty sure Fallguy hit it and the problem was temperature related.

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Re: Bad Mix of Foam?

Post by OrangeQuest » Sat Mar 09, 2019 3:40 am

Fallguy's guess is the one I would go with. Can you see any bubbles in it when you cut it? No bubbles then you will not have much floatation from it. I would think something caused the bubbles to break down and pop.
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Re: Bad Mix of Foam?

Post by Noles309 » Sat Mar 09, 2019 8:46 am

I had the same issues with it. After some time I realized it shrank, I'm talking weeks here, no one ever came up with a reason other than the mix ratios were off or it wasn't mixed thoroughly which wasn't the case. The foam was poured in the summer in the afternoon so there was no great temperature variation. I suspect it was a problem with part a or b but there is no way to really know.
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Re: Bad Mix of Foam?

Post by fallguy1000 » Sat Mar 09, 2019 9:38 am

Noles309 wrote:
Sat Mar 09, 2019 8:46 am
I had the same issues with it. After some time I realized it shrank, I'm talking weeks here, no one ever came up with a reason other than the mix ratios were off or it wasn't mixed thoroughly which wasn't the case. The foam was poured in the summer in the afternoon so there was no great temperature variation. I suspect it was a problem with part a or b but there is no way to really know.
Foam was poured on a hot summer afternoon and cooled some. Why? The reaction is exothermic which is key. The only way to avoid it would be to put a cool(er) foam into a warmer boat, but the exotherm still happens and too cold and it would probably not work. Even the same temperature foam n boat would exotherm foam in reaction(heat) and cool at the boat edges and retract/shrink a bit. It must be temp related, but not enough to worry.
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Re: Bad Mix of Foam?

Post by BB Sig » Sat Mar 09, 2019 12:05 pm

It seems solid and was poured at the same time as the others that did not shrink. The bigger concern is that is pulled away from the stringer leaving a lot of it now exposed/ not sealed.

My immediate concern is do I pour more foam in the gap? Will that seal it or do I need to use epoxy and then foam?

Either way, I appreciate the replies! :D

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Re: Bad Mix of Foam?

Post by fallguy1000 » Sat Mar 09, 2019 12:38 pm

BB Sig wrote:
Sat Mar 09, 2019 12:05 pm
It seems solid and was poured at the same time as the others that did not shrink. The bigger concern is that is pulled away from the stringer leaving a lot of it now exposed/ not sealed.

My immediate concern is do I pour more foam in the gap? Will that seal it or do I need to use epoxy and then foam?

Either way, I appreciate the replies! :D
Take a drywall knofe and cut off the hard edge and refoam if if your volumes are close.
My boat build is here -------->

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Re: Bad Mix of Foam?

Post by Fuzz » Sat Mar 09, 2019 3:45 pm

I would not sweat it, just pore more foam to fill it up and move on.

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