I just finished pulling saturated foam out of my 180 Fisherman restoration as part of my social isolation therapy. 
I'm now adding limber-holes to allow the stringer boxes to drain any water that inevitably makes it's way down into the bilge.
Pool noodles offer the ability to allow water ingress to flow through the stringers and into the bilge. They are also easy. But also a dodgy hack that doesn't meet USCG regs.
I'm considering foam, but I'd use temporary cardboard or plywood to leave the bottom 2" of each stringer box empty, allowing water to exit via the limber holes.
QUESTION: How strong is the foam expansion when it activates? Will it be easy to manage where the foam expands?
Note: I live in the far North. So draining water out of the foam every fall is critical before storage. Water in wet foam will freeze over the winter and expand to break up the air tight structure.

I'm now adding limber-holes to allow the stringer boxes to drain any water that inevitably makes it's way down into the bilge.
Pool noodles offer the ability to allow water ingress to flow through the stringers and into the bilge. They are also easy. But also a dodgy hack that doesn't meet USCG regs.
I'm considering foam, but I'd use temporary cardboard or plywood to leave the bottom 2" of each stringer box empty, allowing water to exit via the limber holes.
QUESTION: How strong is the foam expansion when it activates? Will it be easy to manage where the foam expands?
Note: I live in the far North. So draining water out of the foam every fall is critical before storage. Water in wet foam will freeze over the winter and expand to break up the air tight structure.