Don't do it.
If you are going to use this stuff you need to see what is going on with it. If you mix it incorrectly the stuff may attack itself and start to disolve itself and just end up with a glob of goo in the bottom.
Do it before you put the sole down. Mix, pour and trim. I found a guitar sting works great as a saw - get one that has the center strand and then wrapped with another - cheap too. After that coat the top part you cut with epoxy.
this is good advice
i had to watch that video - a few observations:
the gentlman's breathing ? anyone notice that ? wonder how many ciggs a day that guy's sucking on ?
tools ? using a holes saw that size,to make the holes through the plywood - with a battery powered drill ?
not sure what that wood is,i did notice a few large voids in the end grain of the hatch cutout - marine grade ply will not have voids,i also noticed the end grain has been left unsealed
i'm going to assume this cat is gonna pop the hole plugs back in,pop some glass over them ?
pouring foam - i've witnessed it blow out laminated deck sections - a friend,a know it all friend,used the pour in technique - he discovered th power of expansion...
not sure what the plan is with foaming ? using it as flotation ?
a better plan may be to use the large blocks of foam,like the style for dock floats - just cut the foam to fit...much easier...
let me add this as well:
drainage - no matter what -wateris going to find it's way in the bilge area.with foam poured in,you can't control where this foam is going,if you made drain tubes/limber holes,the foam added in that manner will block the drainage - end result,water trapped...
keep all these things in mind...