I recently spent a fair number of hours rebuilding the centerboard pivot
on #1632. I am disappointed to say that it was largly a waste of time. I
had the same concern about the centerboard riding on the threaded
portion of a bolt and also the pivot on mine could be wiggled about in
the holes drilled in the centerboard trunk. I also though it was
leaking.
Upon disassembly, here is what I found:
The pivot assembly is covered with foam-in-place type foam and then
glassed over.
Inside is a 1/2" x 2 1/2" bolt, two fender washers and an aircraft
(nylok type) nut. All the hardware was stainless steel.
There was essentially NO wear on any of the metal parts. There was some
rusty discoloration of the bolt threads where the nut engaged (crevice
corrosion?) but the bolt did not appear to be compromised as to
strength.
What was more of a concern to me was the condition of the holes in the
cb trunk. There was excessive clearance, most of it in the vertical
axis, and it is not clear to me whether this was caused by wear or a
result of fitting the bolt originally. I wanted to get a good seal
between the bolt and the trunk and I didn't think that would be possible
if the bolt was free to move that much (approx. 1/16") in the hole.
Sooooooo, I made a 1/2" "pin" by cutting the threaded portion off of a
1/2" x 4 1/2" bolt, coated it with paraffin, suspended it within the
loose holes via a piece of wire from above and built up the holes with
epoxy so that two holes, in perfect alignment, with essentially zero
clearance were left after I removed the pin.
I made a new pivot bolt by cutting down a partially threaded 1/2" x 3"
bolt so there are no exposed thread inside the cb trunk, I put it all
back together with lots of polysulfide sealant and .....
Guess what, my boat leaks just as much as it did before. All this really
tells me is that my leak wasn't originally the pivot after all. If it
leaked less, maybe - if it leaked more, maybe. But it's the same old
leak, about 1/2 pint per hour.
Anyway, Sam Finlay and I had had numerous discussions off-list on better
ways to design the pivot and really didn't come up with anything that
didn't require some custom machined parts and even then some compromises
in strength may have been necessary. I concluded that the original
design was close to optimal and certainly practical, especially once I
had figured out how to get rid of the exposed threads inside the cb
trunk.
But I would be being less than honest if I didn't tell you that the 12
year old hardware in my boat was in fine condition when I removed it
despite being used primarily in salt water and that the leak in my boat,
although I suspected the pivot, appears to be coming from somewhere
else.
Dave Kautz
P-15 #1632 Tilly Lucy
Palo Alto, CA
Bernie Johnson wrote....
Got to figure out a way to stop that keel clonking around.....
Keel hinge pin looks really mickey mouse. Looks like the hole in the
keel plate rides directly on a threaded stud or bolt. Whole damn thing
is glassed in as well. Bloody thing leaks a bit also...Redesign....need
a sleeve (teflon?) riding on a smooth diameter (.375 dia. 316 s.s.
bolt).