Stringer foam

[Moose]

Notice the holes cut into the tops of the stringer boxes. They were never glassed back in.

[69Seacraft20]

Wouldn't a watertight hollow stringers be more buoyant than a watertight foam filled stringer of the same size?? Same would apply to stringer boxes. I suppose foam is just there in case hull is damaged not just swamping.

[FLexpat]

Foam has a surprising amount of compressive strength - it also keeps the stringers from flexing and folding/fracturing. Kinda like the core in a deck. You could get the same strength by adding glass but that would weigh more so there is a weight/structural aspect too. Also foam is way cheaper than the glass needed to get the same rigidity.

[FAS]

I kinda think the foam has strength and supports the bottom on both sides of the keel.it is boxed in and when the hollow stringers become full and solid it adds density and toughness,along with flotation.these boats were meant to have it for a reason

[flyingfrizzle]

Be carful if you pour to much, If the tops are on and you pour threw a hole it can expand at a rate so fast it is easy to over do it and crack or swell the stinger case apart. When I did the ones on my 74 I cut the tops out then formed up the sides with wood a few inches higher than the stingers (mainly because I was raising them 2") and poured it in batch by batch. The foam rose up like bread in a bread pain crowing at the top higher than the forms. I simply took a 20" sawzall blade and shaped them to my liking on top then wrapped the tops with glass over lapping to the sides tabbing to the hull. If you are not raising them pour them like they sit then once the foam rises out of the cavities trim it flat to the top then glass the tops closed to get you box back enclosed for strength. The foam density may be effected if it doesn't have room to fully expand in an enclosed compartment or worse it splits something apart. I was filling pontoons on a work barge and found out the hard way splitting welds open as the foam had no were to go.

[20footer]

I know this post is a little old, but does anyone have any suggestions for brands/densities for the foam? I will be re foaming my stringers soon and would like some input. Thank you

[gofastsandman]

Originally Posted by Moose

I think I figured out how to post pics also. Here's a few to show y'all what's going on at the moment..

Are those black truffles there?

US composites or ping member Shine here. He has deals on stuff like that.