Clipper's Vera Cruise Build

Clipper's Vera Cruise Build

Thursday, February 28, 2013

Cutting Transom Batten Notches

This will be a fairly low productivity update because life prevented me from getting much done this week. With remodeling a bedroom and working late several days, the boat had to wait. Sigh!

However, All is not lost because I did manage to get one notch cut in the transom. Readers might remember that the transom bottom edge was cut at an angle of 12 degrees. The next step was to cut notches in the bottom edge for longitudinal batten members to rest in later in construction.

These notches had to be cut at a matching angle to the bottom edge. The idea here is that the transom bulkhead is angled backwards 12 degrees from the bottom edge. The battens run fore and aft parallel to the bottom (more or less) which means they rest in the notches on the transom edge at an angle of 12 degrees. Thus the need for the notches to be cut at an angle.

So how to go about doing this without destroying the expensive piece of mahogany used for the transom? I thought of several approaches, most which were either too complicated or risky. For example cutting the notches on a table saw by holding the board at an angle and running it over the circular saw blade as it is running. For me, this approach, while certainly doable was too risky not only from a safety standpoint, but also from a ruining the part standpoint.

My preference was to use a router to cut out the notch. But all the tools I originally came up with were too complicated. But while I was thinking of how I might stabilize the wood for the circular saw approach, I realized I could use the same method of stabilization for the router and have more control. In addition, a discussion with another builder (Rod) over the phone gave me a few additional tips to consider.

So my approach is illustrated by the following picture.

It works like this. First I cut four 2 by 4 pieces of lumber to the same 12 degree angle as the transom bottom. Then I measured the height of the cutout on both sides of the transom. In this case I wanted to go down approximately 3/4 inch. I drew lines on both sides of the transom designating the notch.

Then using a back saw, I made cuts down to the depth lines on both sides at the ends of the notch cutouts. The back saw was held at an angle of 12 degrees so that the backside of the transom (the higher side in this case) would not be cut too deep. The purpose of these cuts was to give me a place to stop with the router without running the risk of going too far.

Then I set the depth of cut on the router so that it was slightly less than the depth I wanted to cut. This was primarily to give me some wiggle room for further adjustments in depth.

The four 2 by 4 pieces were clamped to both sides of the transom on each side of the notch and the angled edges were all trued up so that I had a smooth transition from 2 by 4 to transom and back to 2 by 4.

Finally, resting the router on the top edges of the 2 by 4's and starting from the high side of the transom, I cut out the notch with the router bit. The bit was a 1/2 inch can shaped bit to give me nice straight inner edges in the notch.

The next picture shows the notch with a scrap piece of wood representing a batten. The actual battens will be approximately 16 feet long and as wide as the notch cutout. I also have to tweak the depth a bit as the scrap is setting just a shade high right now. I would rather have it high than too low, but it can go a bit more.

So I have five more batten notches and one more keel notch to cut which I will do as soon as I can get back out to the garage (remember life?).

The nice thing about this approach is that it is fairly easy to set up and duplicatable for all the notch cutouts including those on the other frames (which will come later in the process).

So that is all for now.

Update 3/1/2013 - Added some additional photos to the construction gallery showing more of the process.

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