We’ve got all the frames built and set up. But we’ve still got to frame the transom of the Palm Beach 22. We’ll build the framework and add it to our setup so we can begin planking. The picture above is a rendering of what our framework should look like. Note that I’ve pointed out a particular piece I call the transom “cheek”. You can see the transom curves inward at the top (called “Tumblehome”). This is part of the signature look of a mahogany runabout.
Now, notice the red arrow pointing to the same piece in a side view. The piece also curves toward the back of the boat at the top. Not only that, it also has a little twist in it that you can’t clearly see from these renderings.
How in the world to make such a piece and get the shape right? The shape has to follow the exact intersection of the side of the boat (topsides) and the back of the boat (transom).
Remember when I discussed Lofting the boat? Well, all the time we took in lofting is about to pay off.As I said back then, we can get any shape we want from a proper lofting. So that’s what I turned to.
Zimmer (the designer) gave us the inward curve in the transom drawing shown at left.
He also showed us the backward curve in the profile drawing but the more accurate method of getting this curve is to derive it from the intersection of the lines from our lofting. Having derived these curves I decided to laminate mahogany to the inward curve and cut the backward curve from my laminated piece.
You can see the form I built here.
Because mahogany is so stiff, I had to do the lamination in three sets of 8 layers of 3/32 thick veneer each.
Now I have a hunk of mahogany that is much stronger than a piece cut from solid lumber since all the grain is aligned along the curve.
Next it’s time to carve our backward curve and twist out of this laminated piece. That’s a story for next time…
Tim, can I ask you what your thinking was in increasing the transom frame size from ⅞ x 2 to 2 x 2 1/16?
Hi Steve,
I believe you’re referring to the piece I call the “cheek”. Since I elected to laminate this piece rather than steam bend it, I decided to beef it up a little bit to make it easier to cut the curve after laminating. Also, I think the added weight of the heavier cheeks is worth it considering the stresses on this part of the frame when it comes time to twist the topsides battens into place there. Hope that helps.
Very helpful, thanks Tim!