Thursday, July 12, 2007

A centerboard case.

Having a lifting keel or centerboard in a small sail boat seems like a wonderful idea. A nice deep fin for beating upwind, and a nice shallow draft for coming in to shore. And it makes trailering easier.

Of course there's the whole problem of the big hole that you make in the bottom of the boat to allow you to lower and raise the keel.

The design calls for a centerboard case which passes through a slot in the oak keel, and there are two oak bedlogs (planks) either side of the box which sit on the keel.

That would be fine if the keel were flat, but the 5/4th thick oak keel is actually curved. The bedlogs have to match perfectly, or the centerboard case will leak like a Government Department. And they have to be aligned so that the trunk case sits vertically upright.

To make matters more interesting, the ends of the centerboard case need to butt up perfectly to the frames - So I need to build the centerboard case before I bend the oak keel over the frames, but I need to bend the oak keel to find the shape for the bed logs.....

- Here's the plan.

I'll build the CenterBoard case with the logs just tacked in place with a screw or two. I'll shift the logs away from the keel so that they only touch the keel at the frames. I'll also just screw the Case to the frames that it buts against.

Then when I've bent the keel into place, I can trace the curve of the keel, cut them, take the case out and complete the assembly and replace it. Glue and screw the whole lot togehter and I'm sorted.

What do you think ?


Chureen said...

Hey Dave,
I'm looking for a pict of your progress. Has the stash of wood decreased in the house? Sarah should be thinking about crawling soon, better clear that up.

Rational Root said...

Ha. She's crawling, she can go from lying down to sitting up on her own, and if you hold her hands, she walks.

We don't let her crawl in in the kitchen, partly due to the impending boat, but also due to the Ceramic Tiles over concrete. Not to forgiving to unstable infants.