Expanding close cell foam?

Is there such a thing that is both lightweight and affordable?

 

Only 2C polyurethane in a confined space can do that.
The single component type relies on humidity to harden. In a confined space the amount of moisture is quickly used up so you end with a foam skin and a liquid center.

 

Thanks. I am aware the stuff in the cans is no good.

How heavy is the 2C poly per m3 when expanded?

 

It can be purchased in varying densities, the basic one is about 1 kg per cubic foot, expanded. Then 2kg etc, but you suffer a weight and cost penalty, although resistance to water absorption is much better.

 

Thats about 35-70kg per m3. Pretty light. So is the 35kg version not really water proof?

A friend owns the legendary Crowther Tri, Bullfrog/Verbatim. It has a really nice sophisticated (for a bulb) bulb bow added to it, it has a V shape to the bottom and sharpish front. My friend said he could make a mold for me so I could put one on each hull of my cat which has an annoying bow down trim due to overly fine bows (you can even notice this issue in my avatar pic).

I thought an easy way to make this would be to actually join the molds straight to my hulls then fill them with expanding foam, then add more glass to make it strong enough.

But I was not sure what sort of expanding foam products are available and would be suitable for this job.

 

I sent these guys an email

http://www.ausurethane.com/pour_foam.html

 

Look at this stuff. Says closed cell for marine applications 2lbs per foot or 70kg per m3.

http://www.aeromarineproducts.com/boat-foam.htm

$350 for 40 cubic feet. 35 cubic feet in 1m3.

How strong would this stuff be? Would it be comparable to PVC foam of the same weight?

 

The lightweight stuff is quite friable and weak, 2kg foam has some claims to structural integrity, but PVC of the same density is much stronger. But not pourable.

 

Cheers. It has to have some structural properties. Not sure the 2kg stuff is going to cut it structurally, IE beaching?

The prices I got are good. $150 for about 250L of buoyancy.

Test samples of the AUSTHANE AUE276 I was quoted are 42kg/m3. Around 200-330kpa (seems strong enough for my application?). It was tested immersed in a bilge cleaner solution for 30 days and it only gained 300g per m2 of exposed surface. (I would fully sheath it in glass and epoxy). Cells are 95% closed.