[C38] mast base

[Ray Torok]

After a day sailing in 25-30 knot winds we noticed that the heel of the
mast had dropped about 5/8", shearing the cabin sole around the foot of the
mast and dropping right through it.  The intermediate and upper shrouds had
enough load and stretch in them that they weren't actually loose, but it
was clear that something in the step had collapsed.

I ended up cutting two access holes in the floor - one on the starboard
side of the mast and one in the head to get better access to the step to
try to figure out what had actually failed.  It wasn't obvious what was
rotten, so I prepared to pull the mast and built an entirely new step, so
that the repair could be done fairly quickly once the mast was out of the
boat.  Working through the new access holes, I made templates of the hull
where the new step would sit, so that I could do most of the shaping of the
new step before the mast came out of the boat.  The new step was glued up
using vertical-grain two-by-sixes, with each layer cut to shape based on
the hull templates.

It really got interesting after the mast came out.  In poking around at the
step, I more or less accidentally broke the whole thing loose from the
hull, and every glue joint in it just fell apart.  The step itself was made
of redwood (not known for its compressive strength), but the offending
rotten piece was 1/2" plywood that had been jammed in to fill a gap,
because the redwood pieces didn't mate up with the underside of the cabin
sole properly.  My boat is hull #37.  Hopefully they did a better job on
yours.

I installed the new step with lots of west epoxy and filler to get a solid
fit against the hull and the top of the keel.  It would not have been
possible to do it this way without the extra access holes.  Even so, the
top two layers of the step had to go on after the rest was installed.
Getting the top surface at the exact angle to match the bottom of the mast
was not really possible.  I guessed at the angle based on measurements of
the mast rake before the mast was pulled, and got close.  With the new
configuration, the cabin sole has been eliminated from the load path. The
cabin sole still has a hole in it, and the mast sits directly on the step.

The good news is that after sailing in some wind, the upper layer
compressed just enough in the right places so that everything fits and the
load is well distributed.   In theory, the step is sufficiently saturated
with epoxy near the surface (all of the surface), that water cannot get
into it.  So far that appears to be holding.  Max winds we've sailed in
were about 35 knots, and as far as I can tell, nothing has moved.

As someone else noted, this is a good opportunity to replace stuff in the
mast too.  I guess that's good news.

Good luck with your repair.  Pictures available on request.

Ray Torok
Thira  #37
San Francisco

On Mon, Jul 20, 2015 at 4:12 PM, Robert G Stammerjohn <
rgstam at md.metrocast.net> wrote:

> My wooden base for the mast has turned to mush and my shrouds have
> loosened. Has anyone performed a repair. I need all help I can find.
> Hull#307 '84. The Boat is good shape otherwise.  help !
>
>
> Sent from my iPhone
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