Why don't boards have adjustable fins anymore? I remember I used to line all the fins up in my tri-fin. (Centre fin all the way forwards, side fins all the way back). Then you could spin the thing around on a dime. Me and my mates used to have competitions to see who could keep spinning it around the fastest.

Most boards dont have it because there is only 1 position which works best for the type of board, the best being a compromise between speed, control (not spinning out), turning etc. Wave boards have a bit different requirment so the US box (adjustable) is used plus the fins are cheaper and smaller thus requiring less fin head area.

rosey is right there is also deep tuttle mostly used where 50cm plus fins required, tiga conic box- the strongest box before deep tuttle appeared and trim box used on bic's and old fanatic's although fanatic used to lock the trim tabs so the fin could only be used in 1 spot.