Make a gluelam block with 3/16" thin strips of ash. If you buy 4 quarter ash you can get 3 strips out of it with the table saw. Smooth that up with a planer if you have one, or maybe a hand plane if you don't.
Glue it to it. I made the following as part of a sliding/adjustable oarlock block assembly. That's almost done now.
.........you could make a gluelam block with chunks of plywood waste too. I will never make gunwales any other way again. Gluelam gunwales are vastly stonger, plus you can make them 3" inches high if you want, let alone as thick as you want. Slow set epoxy gives you all day to get it assembled, plus lots of Visqueen to keep the drips under control.
Cold molded hulls used to be popular, ten to twenty years back. You never hear about it anymore. Back in those days people used huge wide veneer strips. I wonder if there is a way to do it with lots of overlapping 1/8" ash or white oak strips maybe 6" inches wide. I'm not sure I want to buy any more mahogany plywood. I think it's time to leave the tropical rain forests alone. Ash grows like a weed.
........off the top of my cold molding head: make a male plug with cheap construction plywood. Cover it with thin 4mil Visqueen. Use a finish nailer to start one 1/8" ash strip 6" inches wide. Add rows all the way up to the top, troweling slow set putty on the joints as you go. Now start a second rowl 3" inches up, so this layer of 6" wide overlaps joints below. This row of 1/8" strips get resin and putty behind. Staple it on through 3" square scraps of plastic (from orange juice bottles?) so those staples can all be pulled 24 hours later. This wouldn't be ship lapped so you cold sand it up smooth and glass it. Marine plywood requires a second mortgage these days. I'll bet you cold make that hull a lot less than Meranti Hydrotek.
If you made the male plug with 1/4' AC construction plywood you could pull all the original first layer finish nails from the inside, before popping the hull off the male mold.