The transom can now be created by marking the width from the finished top view and the the height from the side view.
Draw a smooth curve from one side at the top to the bottom centerline. Copy this by folding the paper as above. This is the finished transom. Repeat at the maximum width and halfvay to the stem, using the width and height at the two positions to mark the ends of the curves. Make sure the curves are smooth.
This shows the three formers drawn onto the top view. The formers of the jig have been cut out and need sanding to the final shape
The finished jig. Made from 3mm balsa and glued to a piece of 10x20mm hardwood so it doesn't twist or move later. Using a narrow base would give me access to the inside while planking, making marking of the overlap easier. The centerline profile was copied from the side view.
Laminating the two layers of the keel. Here I should have extended the keel down to the jig and glued it there. It would have saved me from having to add a bit more when the planking ended up being a little higher than anticipated. Make sure the the keel is not glued to the jig, except behind the transom where it will be cut off anyway. Another change that would have made it easier would be to make the outer layer of the keel a little wider than the inner layer because that would remove the need to cut a rabbet because the step in width would have served the same purpose. Anyway the keel may have been too wide at 5mm ie 10cm at full scale.
Edited 2015-02-19 re-uploaded missing photos