[Rhodes22-list] Rudder Repair

[Graham Stewart]

David:

I had many cracks and large voids in my rudder (1974) and because I live in
a cold winter climate felt it was imperative to do what I could to locate
and fill the voids and repair the cracks. I repaired cracks but without
filling the internal voids about 10 years ago and obviously that  didn't
last so I decided to approach this problem much more aggressively. I am
convinced that voids will lead to cracking and so they need to be located
and filled. 

I started by repairing the cracks by digging them out using a Dremel with a
large V shaped rasp edge or, for bigger areas and osmotic blisters, I used a
large countersink  on my hand drill.  I removed any loose material
underneath and in some cases there was a lot of loose material - especially
at the top and bottom ends. I drilled holes at the end of each crack to
hopefully ease the tension and reduce the possibility of the crack
spreading. I think it is important to really open up the cracks or the
repair will not hold. When you open them up you will see that in places the
skin is thin and covering significant voids. This is especially true where
there are multiple cracks in the same area in which case you should probably
dig out the whole area..   I then coated the exposed surfaces of the crack
and void with epoxy and then, while still uncured, filled the cracks and
voids with epoxy thickened with colodial silica. I filled the cracks first
before attacking the larger internal voids so that the epoxy would not just
run out.

To address the larger internal voids I placed the rudder on its side and
located the voids by tapping with the wooden handle of a screwdriver. The
location of the larger voids become pretty obvious. I then drilled two 1/4"
holes at the edge of each void on the fist side of the rudder only. I
injected epoxy into one hole until it. along with trapped air, came out the
other using a large syringe that is sold ($5.99) for adding oil to gas and
available at many stores that sell 2-stroke engines supplies. They can be
cleaned with acetone and reused. It is much larger than the small ones sold
by West System and you will need the volume if your rudder is anything like
mine was. The epoxy will recede from the holes as it drains into other
smaller voids so keep topping it up until goes off. 

Use a slow curing hardener - I used 206 and that seemed adequate in my
cooler basement.  I repeated this for each void I discovered and then, once
it had gone off, flipped the rudder over to the other side and repeated the
exercise. It was surprising how much epoxy it took to fill the voids - at
least a quart and probably closer to 2 quarts in my case. I hoped that the
epoxy would find some of smaller voids that I did not discover by tapping
but with that much epoxy added to the core of the rudder I figured that it
had to me much stronger than before.

All this might be overkill as obviously at least some of the rudders were
manufactured with the voids, but once there is cracking, and certainly if
water is draining out, I would want to make the repairs earlier rather than
later. Once the voids were filled I fixed any osmotic blistering. Finally I
coated the whole rudder with about 6 coats of epoxy mixed with aluminium
powder. All of the materials I used were West system - essentially because
that product is most readily available where I live.

I hope this helps. I just finished the repair and it has not gone onto the
boat so I cannot tell you how well it will last. 

Good luck,

Graham 


-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of David Craft
Sent: February-12-13 12:15 PM
To: Rhodes List
Subject: [Rhodes22-list] Rudder Repair

Greetings,

I have removed my rudder for some repairs and new coat of paint.  It seems
to have a few voids that I am filling with epoxy.  I noticed them in one
side when I raised the rudder and it peed for a good while............

Is there a primer to use or just go back with bottom paint.  I have a quart
of Pettit anti fouling paint.

--
Regards,

David B. Craft
Greensboro, NC
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