Expanding epoxy foam?

[piperdown]

https://doc.jamestowndistributors.com/u ... 5.3.18.pdf

Water absorption <= 0.06 lbs/sq ft

Looks PU expanding foam has the ability to absorb water too, although I haven't looked at converting any numbers to percentages.
I haven't looked at the buoyancy numbers in detail but I don't think the epoxy foam is as buoyant as the PU foam.

I was only interested in it due to the slower expansion rate, but if it's not as buoyant I won't be using it.

[OrangeQuest]

They do make the statement that it could be used where you would use foam core or honeycomb.

[Netpackrat]

The dude in the video wants to use it in his rudder, where the buoyancy would not necessarily be desirable anyway

[TomTom]

I recently did an experiment with PU 38 foam ... https://www.amtcomposites.co.za/product ... d-60-rigid

My results have me quaking at the knees...

I poured a sample in a bag and it weight 165 grams.

I then put a hole through it, threaded a string through the hole and submerged it in the pool attached to a dive weight.

It was about 6" below the surface for a month

It now weighs 724 grams...

Thats a lot of water absorption for "bouyancy" foam!!

A technician with AMT has suggested that by puncturing the hole through it, I broke the surface and allowed water to get in... and that had I not done that the results might be different.

This foam states it is closed cell so I thought that wasn't an issue.

Others have stated that if you allow the foam to contact a surface ... eg stringers and sole when pouring in hull, the layer in contact seals itself.

I am now thinking if I do use foam I will make sure that I pour it into the compartments with a temporary lid covered in PVC on the compartment and a vent hole. That way all sides of foam should "self seal" except at the vent, which I will paint with epoxy...

I still have massive doubts about PU foam and would love to hear more comments...

[OrangeQuest]

The dude in the video wants to use it in his rudder, where the buoyancy would not necessarily be desirable anyway

Unless he loses his rudder a lot!