[Rhodes22-list] Marine Tex on Centerboard

[The Rhodes 22 Email List]

Patrick:

>From the picture I suspect that the damage was caused by more than just
hitting the trailer. I suspect that the board was structurally weak due to
large voids inside which may have filled with water. If you have a cold
climate where you are the water would do a lot of damage as it freezes.
Tapping the board with something hard should tell you if there are other
voids and if so, I would definitely fix those first. 

I had this problem with my rudder and centreboard. The fix that I used for
the voids was fairly simple. I drilled holes wherever I suspected there
might be a void. It is best to have more than one hole in each void so that
when you eject epoxy into one hole the air can escape from the other. If you
see any sign of moisture I would wait some time to allow the moisture to
evaporate from inside the board before filling it with epoxy.

I used a big syringe with a plastic 1/4" tip to pump unthickened epoxy into
each hole until it came out the neighbouring holes. It is best to drill
holes that fit the tip of the syringe tightly so you can build a bit of
pressure to push the epoxy in. You will need to top it up several times as
the epoxy finds its way down into the board. Once it won't take any more,
let the epoxy set until it is no longer fluid and then flip the board over
and do the same on the other side. When I did mine I was really surprised
how much epoxy I was able to pump into the core. I am sure I injected more
than a quart. I did the same with my centreboard housing and it took 3
GALLONS to fill the voids.

As for the damaged cavity, I would clean out the cavity, make sure it is
dry, coat the cavity with epoxy and then and fill it in with layers of epoxy
thickened with high-strength adhesive filler. Epoxy can generate a lot of
heat as it cures so build the cavity in layers (about 1") but addg each
layer as soon as it starts to cool. At this point the previous layer will
stop being tacky but still soft enough to scratch it with your fingernail.
If you wait until it cures completely, you should grind a coarse surface on
the old to provide for a mechanical bond.

Using pins is unnecessary. Toothpicks would be useless. Properly thickened
epoxy will keep its form without support. Make the batch to the consistency
of peanut butter.

Use fairing filler for the final few layers as it is MUCH easier to sand.
Try to make the two sides of the board as similar as you can.

I would also be tempted to cover it all with fibreglass as there may be fine
crals where water could migrate. Finally, I would coat the whole rudder with
at least four  coats of regular epoxy. You can apply the coats as soon as
the epoxy will hold properly to the previous coat - about 20 minutes. 

This is a bit of a nuisance but not difficult to do.

Grahame

Graham Stewart
Agile. R22, 1976
Kingston Ontario Canada



-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of The Rhodes 22 Email
List
Sent: February 18, 2016 1:32 PM
To: rhodes22-list at rhodes22.org
Subject: [Rhodes22-list] Marine Tex on Centerboard

Attached (hopefully) are a couple of pictures of the forward edge of my
centerboard.  This damage has come from banging into the trailer axle I
guess.  I would like to try to repair with Marine Tex, which I have never
used.  Any advice?  Maybe after cleaning up the area I should drill a few
holes and insert toothpicks or SS screws to give the Tex something to hold
on to?

--
Patrick Riley
Lakewood, CO
S/V Cleone
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