All boats have some curved surfaces, and the most beautiful have many curves, all hopefully contributing to a cohesive complete package. Some modern boats have curves in only one plane, and that makes construction easier. But traditional wood boats, and ones I wanted to pay respect to, have surfaces with curves both ways. That makes hills or valleys and it gets complicated.
Below is the boat at completion of setting the long trim moldings that define the cockpit, and end at the stern. Now is the time to figure out the shape of the stern.

At the back on the outside, there is the inward curve or tumblehome, that adds width and buoyancy to the back, and just looks cool. And since an outboard motor on a wood boat can look out of place, the sides were extended to enclose it a bit.
New shapes usually begin in cardboard, then on to plywood if I need a rigid pattern. The piece of cardboard laying on top is to visualize how the wall of the engine well might look, and of course, it just came out curved as well.

That makes sense considering the back wall is also curved.

Then, to finish the double curve on the stern sides, internal runners were made for the first layer of tongue and groove shell to follow the side curve.

Eventually, it will be contoured, with both directions relating to both curves at the corner. The complication may be forgotten, and a complimentary form left standing. Beauty has a price.