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EMERGENCY RUDDER MOLD

GCRC's Denis Fraisse and Doug Frolich of Marshall Yacht design conceived of an e_rudder blade design and size that could make it extremely versatile for various size yachts. Once the plug was built, we built the mold and have since pulled a number of blades from it.


Before one builds a mold, one builds a plug which is used to then pull a mold. The plug doesn't have to be as strong or of the same material as the finished part. It just needs to be the perfect shape. It's advisable to save your plugs if you can... you never know when you might need them to repair the mold.


We gave the top of the blade a square profile so we could build a tiller attachment that could pivot up or down depending on the transom profile.

Using tooling resin and tooling vinylester gelcoat we built the mold. On the flanges are centering pegs that are used to align the two halves when it comes time to glue them together.

One half of the mold, trimmed, wet-sanded and buffed out. Underneath we built cradles which were bonded to the mold using sealant. Glass would have pulled on the mold and deformed it.
     

The male centering plugs on the other half. The miold sits on a jig that levels it perfectly.

Time to build the first blade. After waxing the mold and spraying a special epoxy-grade PVA film release, we lay the carbon layers in. The laminate schedule here corresponds to a TP52.


We have to tuck the carbon into the square profile.

The center spar is built around a foam strip. It serves to unite the two haves and stiffen up the blade.

Laminates are placed over the center spar.

Time to bag everything down.

The two haves are out. We will now build a return flange. Not pictured here is a special tool we built to laminate the return flange.

The blade with the return flange is opposite the blade with the spar.


The center spar extends to both extremities of the blade.

Time to bond the two halves together.

We maximize the gluing surface.

Clamp the two halves together using the mold.

The blade in its cassette with a tiller piece fitted to the head.

In this case the transom is vertical and metal gudgeons were available.