Quick question/recommendations
Firstly. Is single to double a Double concave through the fins inside the single concave or single to double is literally as it reads a single concave to double concave being the double conc has same rail rocker as stringer rocker
And second .
Pros n cons of both
( Normal short boards and fishes/fun boards)
I’d say the 2nd scenario, at least that’s how I do it. Not really the exact same rocker cuz it transitions into the single .
I’m not sure about your other question, I’ll let someone else address that.
Most doubles are set within a single, To various degrees depending on what you want flowing off the tail behind the fin or fins. Example…a very slight concave off the tail, double, flat or V. Because whatever you chose will dictate at what point that stringer either stays below the rail line, joins it or goes above with a V. Most concaves are deepest ahead of the fins then taper to whatever your doing off the tail.
Most shortboard/performance shapes have some degree of double. Helps Keep boards feeling lively and loose rail to rail. I like single throughout though too and can have a good connected feel.
Thats all fun stuff to play with but sticking with a smooth single concave and focusing on your rocker, rails and fin placement will be more important first. And have a bigger impact on how your board feels if shaping a standard shortboard