I found that I could not get a water-tight seal using the gasket alone - probably because I was not able to find the proper gasket material here in Canada. I decided to add some butyl tape and that solved the problem. Some say that you shouldn't use butyl below the waterline, but my seal has been holding fine for about 5 years now. I am not sure whether the seal is actually below the waterline most of the time either.
The advantage of butyl is that it has virtually no adhesive properties and is easy to remove. It also compresses very easily. I have no idea whether it is better or worse than the silicone material that Roger used but it is an alternative that might be worth considering in problem situations. I also found that it is much easier to install the bolts upside down. That way you can use a power drill with a torque adjustment to quickly drive the nuts with equal torque. Of course, you need to make sure that the bolts you use are not so long as to touch the floorboards.

Graham Stewart
Agile 76

On Sun, May 19, 2024 at 11:11 AM ROGER PIHLAJA <roger_pihlaja at msn.com>
wrote:

> Hi Peter,
> I may be in the minority; but, I used Dow Corning clear RTV silicone
> aquarium sealant on the centerboard cap, on both sides of the gasket.  The
> job is done so infrequently that silicone removal is a mote point.  I’ve
> only done it once since 1987.   I like the ability of the silicone to
> conform to scratches or other irregularities plus it can flex with the hull
> and not leak.  My centerboard cap has thru bolts vs wood screws.  Use the
> biggest washers that will fit on top and bottom (fender washers if there is
> room) to spread the load.  I used Nyloc lock nuts.  Torque the bolts in
> criss cross pattern as if you were torqueing down a cylinder head.  Don’t
> over torque the the bolts.  When the Silicone RTV is evenly squeezed out
> all around the joint, that’s tight enough.  Let the silicone cure for 24
> hours prior to launching.
>
> Roger Pihlaja
> S/V Dynamic Equilibrium
> 1978  Sanford, MI
>
> Sent from my iPhone
>
> > On May 18, 2024, at 11:30 PM, peter beckerman via Rhodes22-list <
> rhodes22-list at rhodes22.org> wrote:
> >
> >     I got my boat in the water today and am very happy to report that
> the 3/16" line I'm using is working fine and my centerboard now deploys
> properly.  I do not find the line hard to manage though I suspect that 1/4"
> might be better.   I am extremely unhappy to report the steady drip I'm
> getting from the centerboard cap.  I tried to torque the screws down, but
> that didn't solve (or help) the problem.  Therefore I took the boat out of
> the water and expect to remove the centerboard cap and do a better job
> cleaning the mating surfaces before reassembling.  Question for anyone who
> has removed the centerboard cap:  did you use any sort of caulking or
> sealant when reassembling the cap?Were the screws sufficient to create a
> tight seal?
> > Thanks,     Peter
>