Think First

I have been doing more thinking and questioning than usual, and consequently less cutting and gluing, but I think it will benefit the project in the long run.  Most of the thinking has involved the centerboard and the centerboard case.  The plans call for a centerboard of 57 inches in length, which sits neatly in a slot that is 58 inches long (forward edge of frame 6 to aft edge of frame 4.)  That my slot actually measures 57 5/8 inches rather than 58 (probably due to the curvature of the earth) is a bit of a problem, but far from an insurmountable one.  The bigger problem is an apparent (dare I utter it?) flaw in the plan.  Try as I might, I cannot see a proper head ledge at the aft end of the case.  Rather, the case seems to depend on the frame and floor where they abut the case plus a partial head ledge (called a "spacer" in the plan notes) that sits atop the floor at frame 6 to keep the seas out.  I asked two people to review the plan to tell me I read it wrong, including my faithful co-adventurer Aussie Andy, a Grey Seal builder in Melbourne, and Bruce Mackenzie, a master boatbuilder with years of glued plywood experience and a lifetime building wooden boats.  Both see it the same way I did, so we are either all misreading the plan or else there is a serious potential for a leak due to the built-up design of the aft head ledge.

Fortunately, there is a pretty easy fix.  If I sacrifice 5/8 inch at the aft end of the slot, I can run the head ledge all the way through the slot to the bottom edge of the deadwood.  It can be 1 1/2 inches for to aft where it sits atop the floor, and notched to 5/8 inch as it enters the actual slot and continues down to the deadwood.  This will give me a continuous wood barrier from the top of the case to the bottom of the deadwood -- more in keeping with the traditional centerboard case head ledge.

The aft head ledge showing notch to cover aft edge of slot

Head ledge in position in slot.  It is plumb -- honest!

 
I expect to have to reduce the length of centerboard by an inch to make up for this (and my lost 3/8 inch as well) and will do so at the forward edge, where there will be less impact on the weight.  Once again, the Bruce Mackenzie/Bud MacIntosh mantra "It's not the mistakes you make, but the way you back out of them" gives comfort.

Inside of starboard case side and case log.  Epoxy coating on plywood

My other mental effort has gone into how I would install the laminated floors (actually partial frames) that the plan calls for at stations 6 1/2 and 3 1/2, given my decision to install these with the hull upside down.  Aussie  Andy shared a picture from the late Gert Sigvardsen who did his laminated floors the right way -- after turning the hull.  Clearly it would be easier to wait, but not impossible not to, so. . . . .


I installed 6 1/2 this morning.  I drilled a 1/2 inch whole in the center of the three 3/8 inch strips and applied glue.  I applied a glob of thickened epoxy to the upper (contact) edges of the bottom three planks as well as the keel. Then I temporarily ran a keel bolt through the deadwood and used it to crank the glued up floor into position. The bolt is well coated with wax where it goes through the glue up, so I will be able to remove it later to facilitate installation of the lead ballast. I had to use a jack at one point on the starboard side to keep the floor against the plank, and a temporary screw at the same point on the port side.  Otherwise,the  floor laid nicely against the planks with no additional pursuasion, and it turned out to be one of the easier glue ups I have had to do thus far.

Floor at station 6 1/2 with jack to hold tight to plank

Floor in place.  Spring clamps to hold lams together

As this will be my last post of 2011, please accept my best wishes for a joyful Christmas and a very happy new year.