In your "dispatching" of many Sunfish relics, haven't you found the empty space between the cockpit and hull is "factory", designed-in, and always present?I had the same problem with an old hull that was destined to be a hard use "beach banger". I ended up drilling two holes in the bottom of the hull
right over the hollow area and then squirting in about half a can of hardware store exterior Right Stuff foam-in-place foam. Make sure the holes are the same size of the Right Stuff tube. I then repaired the holes with MarineTex. It worked but not my finest boatwright hour. Yeah, I know, Right Stuff is not marine grade and might soak up some water in the bilge - a quick and dirty repair at best.(Name withheld to protect reputation)
If you've already started, may I suggest a turkey baster? ($1 at Dollar Tree). Also handy for refreshing brake fluid in the car's brake fluid reservoir.Sorry. posted before I finished Has anyone else encountered this? I am guessing we are going to have to drill a series of holes in the hull and inject expanding foam or thickened epoxy to reestablish a bond between the old foam and glass. Several questions. Will Thixo bond to old foam and raw glass? Is it to thick to spread out to cover a large area. Will it just melt the foam? Would an expanding foam bond enough to hold the hull back down to the foam? How many holes would I need to drill to be able to cover the area? We are stuck at this point until we address this issue.
L & VW, I found it odd that this flex is only on starboard side of the cockpit, the port side is solid. I agree with the little goes a long way , we encountered this several times resetting all our forward blocks. It will be a challenge but I think our plan will work. Will advise when completed. ThanksI've checked my three Sunfish, which happened to be stored deck-down, and resulted in the same findings.
While there is some flexing (flexion?) between the cockpit and the hull bottom, it took an ample push—using my thumb and index-knuckle. The rest of the hull flexed somewhat less.
Keep in mind that "a little goes a long way", and over filled, can actually cause damage.One "turkey-baster-full" will probably do the whole area.