There are many ways to make curved parts in boatbuilding. The simplest is overbending. If possible it is worth using them. Just lay out the element cut from a straight strip bend it to the desired shape fix it (e.g. on a table) pour hot water or grease it with a brush and heat it with a heat gun. Or just leave it for a day and increase the overbending the next day if necessary. After a weekend, a straight strip may already be completely crooked. If the piece will be fixed in this shape in a new place (and will not be this shape as, for example, a frame) then the matter is over.
Here a mini bulwark for the bow deck of a motorboat.
