The new rudder

by Dermot Tynan in Microtransat

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Posted on Thursday, October 03, 2013 at 08:00

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Thanks go to Colman Corrigan for designing and building the keel and rudder. The keel follows the traditional NACA shape, with a rounded leading-edge, tapering off to a narrow trailing edge. It is approximately a 6318 shape, with the maximum width being about 36% of the length of the cross-section. Overall, the keel is coming in at about 750mm from hull to the end of the bulb, and about 240mm from front to back. That's a 3:1 aspect ratio.

The bulb is made of lead, which will be encapsulated in epoxy. Currently it weighs about 12kg, thats down from an original weight of 18kg! It can be removed from the boat via the two stainless steel threaded rods which go from the bulb up through the fin keel and through the hull. Eventually the assembly will be glassed in place, but for now it's handy not to have to carry the whole lot around.

Now that the wiring loom or harness is in place, and the rudder and sail servo "tanks" are mounted, the deck panels can be installed permanently. This is a key step because once the panels are sealed in place, and the gunwhales are taped and epoxied, the hull itself is complete from a fibreglass perspective. I have held off mounting any of the core electronic systems until this stage is reached, to avoid working with delicate circuit boards and epoxy at the same time. After this stage, the real servos can be mounted and all of the main components can be permanently installed. Obviously the keel will need to be glassed in, but that is on the underside of the hull.

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