Ever wondered what the different tail shapes on boards are for?.......

Here are some words from a legendary shaper......Wade Tokoro:

Although tail shapes are an important part of surfboard design, many surfers remain oblivious to the effects that tail shape has on how a board rides. Were you riding a round pin at 1-foot Creek? A swallow at 6-foot Haleiwa, perhaps? Repent! To give us the 101 on how your tail works, we rang up the esteemed Wade Tokoro: a man with more than 25 years of experience behind the planer for some insight.
Because pin tails have less surface area than other types of tails, they’re going to be fitting into the wave tighter and giving you more control over your board. True pin tails are typically used in really hollow, barreling surf—think Pipeline or Teahupoo—because at the end of the day, you really don’t want to be sliding around too much out there, you want to be in the tube. As a basic rule of thumb: the wider the tail, the looser the board.
Most of the rounded pins that I make are shaped for step-up boards. It makes a lot of sense if you look at the design of the tail. You’re taking the same approach that you have for a pin tail—you want something that will grip the wave a bit—but you’re adding a touch more surface area, which loosens up the feel of the board a little. A good example of a place you’d ride a round pin would be Sunset on a pretty solid, but not totally maxed-out day. You still want to be able to hold yourself into the wave, but you also want to have the option of drawing some lines and doing some turns.
Squash tails are usually a safe choice and they make up the bulk of the boards that I shape. Because of their outline, they’re really user friendly and versatile in a lot of conditions. It’s a design that suits the type of waves that most of us spend our time surfing. Because of the way the tail sits in the water—being stubby and wide—you’re able to get a lot more out of your turns and the board feels a lot looser because it’s not gripping the wave as much. It’ll also carry you through the flats pretty well and should be your go-to choice for small to medium-sized surf.
I mostly cut swallow tails when I’m shaping a fish and other playful types of boards I’m making. Because the design is so wide and there’s so much surface area, you can really sink it when you’re riding it. The design’s mostly conducive to small, playful types of conditions when you want to slide the tail around a lot.