Mast leaking

Hi all. I got great advice on my last problem raising the mainsail so asking for help again. Flipped my 1986 Hobie 16 this weekend. Yes my mistake and buried a hull. So as I climbed on the hull to right her the mast started sinking and eventually ended up turtleing. So after getting lots of help I noticed a hole at the base of my mast. However water most likely got in on the top of mast. Anyone know how to determine where my holes are and tricks to sealing it to be watertight? Thanks

One way to check for leaks is to take the mast off the boat and wade into the lake with it. Hold it under water and look for bubbles. Seal small holes with silicone. Larger holes can be sealed with a rivet with a rivet cap and silicone.

Thanks Jim. That's what I though. Already riveted one hole at the base.

This is from a post I posted last year!

I had the strangest situation with regards to water in the mast.
Last season I had my first and only capsize, on holiday in France, fortunately I had a float on the end of the mast, well it took three of us to right the boat. Myself and two nice kayakers that came to my rescue, I thought hang-on thats not right.
Two days later I stripped the boat down ready to transport back to Blighty and on de-masting I noticed a swooshing about with in the mast.
The thing is no water would come out, in the end I drilled a pilot hole at the bottom so as to drain it, it took ages to drain so it must have been pretty full and that would explain the problem with righting the boat.

Two weeks ago I thought I would sort it out, so laid the mast under water let go and it kept floating, dunking under, no bubbles nothing.
No leak was detected, I was like how can this be?
The only assumption I have made is that the mast only leaks when under tension, when the mainsail is rigged, what the heck?
So I decided to pop the rivets holding the masthead, silkaflex'd around the rubber plug (that had deteriorated over the years and replace the rivets of the halyard swage plate. But before doing so I gave it a blast with some expanding foam through the lower rivet hole of the halyard swage plate in the hope it would expand and seal around 12 inches of the top of the mast.

Re-attached the halyard swage plate with coating of sikaflex sealant and re-riveted with SS rivets and the same with mast head.

Finally had a chance to carry out a controlled capsize while mast was under tension, glad to say problem appears solved.

Hope this helps!

Cheers,
SRG

_________________
Hobie 14 Turbo (~1979)
Hobie 16 Carumba (1983)
Hobie 16 1990 (storm damaged)
Hobie 16 1996 (my latest)

Thanks. Interesting problem. I think I have solved the problem but am purposefully flipping it next weekend to make sure. Otherwise I'll look at what you have done.