Basically, is it just take your regular board and add 2-3 inches in length and 1-2 liters in volume (mostly by slightly adding thickness rather than width), maybe round pin tail?
does anyone advocate more extreme design changes (eg, increase in rocker, reduce concaves)
or do you reject the entire premise as being too close to the thing it is stepping up from to be worth it
I like step ups and think they're a thing. My "HPSB" are definitely small wave daily drivers. They go great in North Florida's stomach-head high windswell chip in peaks/bowls, often a reform underneath the peaking/capping/barely breaking outside. Go good in 90%+ of Central America, too. Redline pretty fast (for me) in Mainland Mexico, and that's with no crowd to fight. Chest-head high "flat" day at the beachbreak, yeah they're a joy. Anything else, err....
I think regular shortboard + 2-3" length, maybe + 1/8th thickness, rounded pin and 5 FIN BOXES is a decent starting point. Most of the actual good/fit surfer HPSB I'd have to bloat them into the Sub-Donkey enabler or add 2-3" and some thickness to even ride them in the first place, so YMMV.
Sometimes I advocate more extreme design changes. For dumping beachbreak pits, I think more rocker is in order. Probably a good idea at pumping sand point drainers too. For points and reefs (think Punta Rocas in Peru) I think less rocker is the call, and maybe even a hair more width.
If you'll be surfing both I say bias a bit towards less rocker so you don't get frustrated getting caught behind at points (unless you love frantically pumping, potentially after opportunistic shoulder hoppers trying to shut the door on you), and forget arm bar air drop right into the gas chamber approach at the beachbreaks.
I say 5 boxes because if you want a bit more down the line speed at something walled, the quad will help you there.
