[Rhodes22-list] Center Board leak

[Graham Stewart]

My solution was probably overkill but it was prompted by the fact that the
cap over my centreboard trunk had been glassed in place and then sealed with
5200 - type sealant. This absurd approach made removal of the cap a
nightmare and resulted in the cap having a badly damaged mating surface and
being  broken in half when I finally got it off. 

Anyway, the matching faces were badly damaged and need to be repaired. To
get  a perfectly matched face I fashioned a plate to cover the trunk from
1/8" aluminium and then used the plate to create a smooth face on the cap
and to hold it all in place while I mended the break. I did that by covering
the aluminium with wax paper as a release agent, covered the mating surface
of the cap with epoxy thickened with cabosil and then clamping the whole
thing to a bench top to make sure it stayed flat. I then separated the cap
from the aluminium, and then used the other side of the aluminium to do the
same with the trunk except that this time I didn't use wax paper as a
release agent as I wanted the plate to be affixed permanently. I also rough
sanded the aluminium just prior to applying a coat of unthickened  epoxy and
then, once tacky, applied the thickened epoxy and attached it to the trunk
using rivets. In order to make sure the rivet head was below the surface of
the aluminium I had drilled a larger hole part way through the aluminium
just deep enough for the head. I then filled the holes with thickened epoxy.


That gave me a good and rugged matching surfaces. I then made a gasket from
a sheet of neoprene my neighbour had and glued it to the aluminium base with
gasket cement. I applied silicone to the upper surface of the gasket and
then bolted the cap down using 1/4" bolts using large washers and lock
washers. 

As I think back, I don't know why the aluminium didn't distort when I
attached it with the rivets so I think that if I were doing it today I would
attach the plate without rivets and clamp it in place with the cap while the
epoxy cured. I think I would use release agent on the aluminium plate to so
that it could be removed and then use the gasket directly on the now flat
fibreglass surfaces - having beefed up the cap considerably to be much
stronger.

It didn't leak and when I needed to, the cap came off fairly easily as it
appears to have gradually broken its bond with the surfaces. I the process
of removable the neoprene was not salvageable and the silicone had to be
scrapped off. I don't know that the silicone was necessary but in the
absence of perfectly matched surfaces without any scratches or bits of dirt
I thought it was prudent to use it. Still, not having silicone would make
removal of the cap easier so I think that next time I will skip the silicone
and see how it works.

The point of the aluminium was to create a flat unblemished surface and none
of that would be necessary if the surface is already in good condition but
it doesn't take much in the way of scratches or imperfections for a leak to
form. A piece of plywood would serve the same purpose of creating a flat
surface. As it turned out, though,  I am glad to have the aluminium base
there for the gasket - I just think I was lucky that it remained flat.

Graham 


-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Michael D. Weisner
Sent: September-18-13 1:37 PM
To: 'The Rhodes 22 Email List'
Subject: Re: [Rhodes22-list] Center Board leak

I always had to use 3M 4200 on the seal on my '81.  I too had a problem with
just the gasket - lots of leaks!  Maybe there was a problem with the form
that was used to make the CB trunk & cap in those days.

Mike
s/v <-- NoName -->  ('91)
Nissequogue River, NY



-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of rbeytagh
Sent: Wednesday, September 18, 2013 1:24 PM
To: rhodes22-list at rhodes22.org
Subject: [Rhodes22-list] Center Board leak

Wow....I just splashed my boat for the first time simply to see if the new
center board gasket I installed  was water proof. It wasn't....water poured
in as if there was nothing there. I tightened all the screws but this only
slowed down the in-flow a little. Stan is adamant that no silicon should be
used to seal the gasket, but apart from this I can't figure a way to seal
this. Any suggestions?

Thanks
Richard - S/V Waif
Asheville NC 



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