I elected to pattern each with scraps of planking material... easier to shape than the 4/4 yellow cedar. Still, spiling the shapes to the bottom at each of 4 stations turned out to be fussy work, especially for the first couple. Running out of propane for the heater in the middle of the work made for a long session.
When each pattern was close, I traced the profile onto cedar blanks and bandsawed them to shape, and adjusted the profile as necessary with a block plane. I improved sufficiently over the sequence to motivate me to redo the first of them.
I left the floors at stations 4 and 5 un-shaped on the top. as I have not yet decided how to tie them into the daggerboard case.
About 6 hours over two sessions, including thickness-planing the stock.