Watch more How to Choose a Surfboard videos: http://www.howcast.com/videos/507795-What-Is-a-Pin-Tail-Surfboard-Basics
Basically the pin tail is kind of like your round pin, except it’s really pinched at the end of the tail. And what that does, it has less area than any tail, and so at high speeds and big surf you don’t need a lot of planing surface, and you need more control. So that’s why they pull the tail in to give it more control. And what that does, the water flow flows down the rail line into a tight, tight pin tail down in this area, down in the tail area. And what it does it really gives you the maximum holding power in bigger surf. And why that is, is because in big surf you’re traveling so fast that the tail with less, if the tail had too much area, it’d be really hard to turn. With the pin tail, it’s squished at the end, so you get the maximum control. And that is the pin tail.