does the center fin in a modern 3 fin thruster shortboard provide any drive. i am assuming it does, unless the fin is very small. thanks.
all fins provide drive… but the back fin moreso than the rail fins because it’s behind your back foot. You tend to turn off the rail fins and get drive from the trailing fin. Twin fins have the fins back further than the rail fins on a thruster because they need to do both. Same with a single fin.
Try taking it out and surfing it as a twin to see what it does.