I have had minor leaks from the wiring that passes through near the
mast step. I resealed the sockets.
I have had leaky windows - went the whole hog and replaced them due to
cracking, corrosion and similar.
I have not had any leaky stanchions, but there were some deck holes
adjacent where water was leaking.
Finally, I realised the main leak was, as you suspect, at the
chainplates.
Of all the issues, this is the worst in a C28, as they are
fibreglassed onto the hull inside. C29s have it easier.
There are 3 chainplates per side, I found it was the Port, Aft, Lower,
which aligned with some minor marks and the old holes in the deck.
Deduced that there was a boarding ladder there at some stage, probably
berthed in a marina and bumped against the dock or something.
The aft chainplate comes into the cabin just aft of the main bulkhead,
above the shelf. After it passes through the deck, it is bent 90
degrees aft and flattens-out, some 150mm or so below the deck.
To remove it, remove the shroud and relocate all gear from the cabin,
fit a plastic dust sheet everywhere you can, as the dust will
penetrate. Choose a cool day and get a diamond disk for the angle
grinder. Wear disposable overalls, tape the wrists around your
gloves and ensure you have a good respirator with full face hood. If
poss, get an industrial vac cleaner to run continuously, wear ear
muffs and look forward to a bath inside the overalls.. Go for it with
the grinder and cut the glass off the surface of the chainplate. An
area, if I recall right, some 150 to 200mm long and 50mm wide. You
will see the black stainless steel, it will go silver if you touch it
with the grinder.
Simply grind the glass off, the chainplate will come loose.
It took about 15 min for me, but then I have done a lot of
boatbuilding and fibreglass work, I was also fully aware of the dust
and mess.
When it comes loose. gently work it out from the deck. I then ground-
off the majority, but not all, of the built-up glass inside the hull.
I could find no corrosion, crack detector spray showed no cracking, so
I was happy to replace the plate.
This is where I was careful to have NOT removed all of the built-up
glass, because what was left gave me a location pocket to get it
right. After I washed it all in acetone, I put some sealant under the
deck, some resin on the hull and "glued" the chainplate back. I then
applied 2 layers of CSM, well rolled. 4 hrs later, another 3 layers
of heavy CSM (can not recall the weight, but it is thick) then next
day I applied a nice thick flowcoat.
Another full day to clear the dust from everything as I did not cover
it all adequately.
Never had another leak and the hull looks nice and white.
It is a bugger, but worthwhile as a check of the chainplates. Better
than any surveyor will ever do.
Have fun.
Roger