Ok that makes sense. I have spent a bit of time in the bilge and have not noticed the flex you mention. Prob as you say no two were made alike. My bilge is wide open and the pins for the grundgen go thru solid FRP. Could be a PO removed all the foam?

I agree with the better safe than sorry approach so I'm going to ebb-o-fy with bulkheads too. Cant hurt and looks pretty straightforward.

Andrew