Hi Jim,

I'm a bit hesitant about using expanding foam, it seems to be a little to permanent. I know if I use the foam, and then have to repair a hole etc in the hull, then the foam is probably going to be in the way (see also;Murphy's Law). Placing a patch of glass inside a hull with the paintbrush-on-a-stick method would be difficult enough without having to first invent a chisel-on-a-stick method of removing the foam.

I'm thinking of going with some sort of inflatable bag, I've seen some used on sailing dingies, so I guess there will be some comercially available. Also if you inflate them in the boat they should wedge themselves nice and tight, and be easy to remove.

Paul.