Adding expanding foam to a hollow wood board!

My first build (of two) was a 9’ 6" SUP a couple of years ago.

Too heavy, not the best for messing about on canals, hard to surf but it’s mine and I made it!

I’ve had a number of cracks and leaks in the time I’ve had it from hard use. I thought I had them all sorted, even using the swimming pool at work to try check for more leaks!

However, went out the other day for a little paddle and popped open the deck hatch to get the fin key that I store there - this was the sight! The mould I’m not too concerned about as some is from where I’ve had it wet inside before but clearly this time it has been damp inside without realising for quite some time! Now it’s caused the stringer to start to delaminate. (Sadly I didn’t know of Brad’s idea to coat all the internals in glue when I made this)

While out I did a bit of hopping on the board and it felt like more of the board was separate from the stringer - clonking!

So I’m not toooooooo worried. It will be sad if I can’t actually get surfing on this (I’ve not mastered it yet!) and I think it will probably survive enough to just use as a second board when out on the canals in a low stress environment.

I’m considering the options after drying it as best as possible.

Would putting as much expanding foam as possible inside be a reasonable idea or absolutely daft? I thought it could be a good way to add support.

Adding more weight is a concern but I can’t see an alternative.

Any thoughts welcome!

When that stuff expands it does it with quite a bit of force and some heat.
Considering how you’ve described the situation, it might actually blow the board apart.

Exactly. The stuff also isn’t cheap. Would probably also invite rot since things won’t dry out.