Boat Forum / Cruising / November 2005

One source tells me to drill small holes through and through the rudder
in a grid pattern, lay it across some sawhorses and leave a small space
heater set to low under it for a few days, checking with a moisture
meter, flip it over, repeat the heat.  When done, back fill the drilled
out holes with a mixture of the sawdust and some epoxy, sand smooth and
get ready to do it again soon :-(  I feel your pain.  I had the same
surprise with mine when repairing some freeze cracks a couple of years
ago.  3 large hunks of mahogany fashion into a balanced rudder.
Whoodathunk?

That could be tricky depending on the degree to which the worms have had
at the wood.

I've actually thought about taking my glass-wrapped wooden rudder to a
shop that does aluminum fabrication and have them take some measurements
and build a rudder to match the shape of the old one.  I'm thinking
about a structure similar to that of an aircraft wing but somewhat more
robust in terms of the thicknesses of the components.  Just a thought.

Build a new rudder using the existing wood as a mold.

Use some plastic sheeting such as Contact to cover the wood and serve as
a mold release.

Use some 17 Oz, double bias, knitted glass and epoxy to cover the wood mold.

Make sure to include a flange on each half so you will be able to get
the two glass pieces off the wood.

Destroy the wood exposing the existing rudder post and tangs.

Position the glass half shells around rudder post which are now clamped
together with screws as required.

Pour 2 part urethane foam into a 2"-3" hole in the top you have made
specifically for the purpose.

Make multiple pours over a 2-3 day period. (Foam continues to expand for
about 24 hours so be patient)

When rudder is full of cured foam, start grinding away flanges a few
inches at a time, the lay a piece of glass over the ground area covering
both halves.

This process sort of duplicates tack welding if you were working in metal.

When glass halves are completely bound together with strips of glass,
add some fairing putty, then seal with high build primer.

Somewhere along the way, seal the rudder post to the glass with SikaFlex
291 or equal.

You are good to go except for bottom paint when rudder is reinstalled.

There is something about wood you should never forget:

From compost you come and to compost you shall return.

The wood in this rudder has started the return journey.

Lew

I'd add heat to your mix. Another thought: Enclose in plastic and vacuum
it, but that's pretty noisy.

Your plan would be sufficient. I'd use epoxy or vinylester, not
polyester, though polyester was sufficient to keep our wood-cored rudder
dry for 20 seasons.

If you have the time/inclination, try to reshape the rudder to a NACA
foil shape, or at least less barn door-like. It makes a big difference.
I have a simple spreadsheet of the NACA 0012 foil at
<http://homepage.mac.com/jerelull/FileSharing.html> There are other NACA
foils, but I was told this was the best one.

"beaufortnc" <mikeandkate@gmail.com> wrote in news:1133221543.412096.125250
@g43g2000cwa.googlegroups.com:

Drying oven of a car paint shop!  Bake the water out of it.

They have hangars to dry car fender parts that should work perfect.