The Tirrik’s centerboard, centerboard trunk and beaching rudder

I’m jumping around a bit in the build sequence to keep the project moving while waiting for the planking material to ship.

I have laminated the rudder blade and centerboard from four layers of 6mm okuome. A doorskin pattern from the previous build was used to shape the top layer of each, and the other layers were cut slightly oversize to allow for less than perfect alignment during glue-up. Once cured, the parts were trimmed to the shape of the top layer using a flush-trim bit in a router.


Constructing the rudder

I hate routers. They scream in my ear, and it is often difficult to see what the bit is cutting until it is too late. But in spite of this, I use both of ours extensively to replicate plywood parts; nothing else does the job as fast or as accurately.

The centerboard as shown on the plans has no lead in its tip. The Caledonia Yawl has something like a 6″ lead -filled hole near its tip. I drew a suggested cutout for lead on the centerboard, as I like a slightly ballasted centerboard. When a board has some lead, it won’t need to be restrained to remain in the down position. This means the board can be left fully down, yet it will be free to swing up into the trunk in the event of a grounding. I usually use a bronze pin in a bushed hole to hold the board in the up position. It is very tidy and secure, but doesn’t have the adjustability of the “pennant tied to a cleat” approach.

Centerboard Trunk

Centerboard Trunk

The rudder blade will need control lines to hold the board up and down. I find that the rudder will stay down at lower speeds without tensioning the “down” control line. This is nice when sailing in thin water, since it will readily swing up when it touches bottom. As speed increases the rudder blade will lift slightly, which makes for a heavy helm, but control isn’t lost. At this point, the down control line comes into play. When the rudder is fully raised for launching and beaching the blade is still immersed enough to provide good control of the boat.

Beaching Rudder

Beaching Rudder

I like to have the rudder control lines run inside the rudder trunk. The lines can have a large sweeping radius and exit the trunk with a very fair lead for operating the lines. The plans show the control lines outside the trunk, turning abruptly at right angles exiting the tiller. Iain’s method is simpler, but has more friction and is not particularly elegant.

While waiting for glue to cure I milled and shaped the partner arms and wedge. I like to use teak on these high wear areas that would be difficult to keep a finish on.

Mast Partner

Mast Partner and Wedge

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