Rudder rebuilt for a Vivacity 20

The original rudder. The rudder stock extended into the water with a paddle type blade.

The original rudder had very little shape. The leading edge was rounded and the trailing edge was faired a bit but it was basically a plank..

The proposed foil profile was traced onto a piece of aluminum and cut out. This was then used as a gauge during the shaping of the new foil.

The profile used was copied off a J22 rudder. The gauge is checked against the original J22 profile.

The rudder was then modified to extend the existing blade above the waterline.

The original rudder was made from laminated maranti planks. The same wood was used to extend the blade profile.

The new extension being glued and clamped into place. Epidermix Epoxy Glue was used.

The blade was profiled using a variety of tools. Hand plane, power plane, orbital sander, hand sanding, but I found a 115mm angle grinder with a sanding disk attachment worked best with a 120 grit paper. The only down side was the mess it made of my garage. A breathing mask is highly recommended. A hand plane was used every now and then just to smooth out the surface once the profile was about right. The original bade was not thick enough for the profile I wanted, so I built up the thickness in the middle of the blade with a paste. I made the paste by mixing micro-balloons(fine white powder) with polyester resin. This sanded very well .

Preparing to laminate a layer of cloth. In the background is a cardboard box that I used for the squeegee to spread the resin. I cut a piece about 100 x 80 every time I need one and throw it away afterwards. Cheap and does not need cleaning.10 oz glass cloth used with two layers on each side. I used a piece of cloth about 1m x 1.2 m in total.

Polyester resin was used for the laminating. You need about 1 teaspoon of MEKP (hardener) per paper cup. One cupful is sufficient per layer. Resin is soaked into cloth. The edges where wrapped over except on trailing edge. Edges are trimmed neat once resin gels but before it hardens too much. Once the resin is dry the edge of the cloth/resin is faired down before the next layer is applied. I put on one layer at a time, alternating sides.

The rudder was finished by painting a gel coat on the outside. The standard pre-colored gel coat I bought was too thick and did not give a very good finish. I thinned the gel coat down with iso-resin (also a polyester resin but much thinner than the usual stuff you buy at a hardware store). In fact you should be using iso-resin all the time as it is stronger and has better water resistant properties. I used about a 50/50 mix and applied with a paint brush. The result was a finish that required no further water-papering or polishing. It almost looked as though it had come out of a mould.

Rudder fitted to boat. Clearance between the back of the boat and the leading edge is about 10 mm.

And this is why we go to all the effort. Opening cruise Sept 2006…….