Can someone please explain to me the function of the different tails available on surfboards (square, pin, swallow). Thank you.
the hypothetical end of the board where water flow leaves to resume its former identity as a fluid medium. and the fish shakes free of the hook to swim free and grow greater. ambrose at the baithouse
Tom, With tail shape you have at least two things going on. First, the shape of the tail: square, pin etc. Then you have the curve of the rails: soft, hard, in-between. A square tail has a lot of surface area ie: planing area, so it will lift the back of the board and plane through the water. On the other end of the spectrum, a pin tail, is really an extended rail that comes to a point. Pin tails are easier to turn rail to rail than a square tail. A squash is a square tail with rounded corners, and bites less than a sharp-cornered square tail. Swallow tails allow you to have a wide tail for more planing area, but give the effect something like a pin tail on turns. Then the rail edge, (sharp or soft) comes into play. The big word to remember is RESISTANCE. The sharper the edge, the more resistance will be introduced into the energy of the wave and the more wave energy will be “caught” by the rail. A soft tail will usually be forgiving, and have a smooth feeling on turns, but may have a “sucking down” effect on the back of the board. Sharp or hard rails in the tail will plane and have more drive in turns. Look at pictures in the magazines, and you’ll usually see a clean slicing of the water off the tail of most boards, because most boards have hard rails in the tail. You might want to talk to surfers about the tail shape they prefer. You’ll probably get some passionate answers. Some people think that the performance of different tails is all in your head, but I disagree. Everything on a board plays a part.
Awesome Doug. Speed and drive is usually a consideration. Simmons made his tail blocks wide, but some argue pins have less drag. I’d like to add one more element to a board’s tail shape - rocker. Fins have a nice little part in this story also.
Thank you for the help. That is just what i was looking for.
how about fin placement? if I set the fin all the way back isn’t that supposed to decrease drag due to tail rocker (less fin in the water)? so why do you get more control that way?
Fin placement is a very important aspect of board design, and I think it’s not understood all that well. I have had the opportunity to talk to Joe Blair who used to shape for Dick Brewer and Simon Anderson. He continually says that most shapers set their fins too far back. His side bites on a 9’ longboard are set at 18" from the tail, and the back of the center box 6"-7" from the back. He claims, and I’ve seen it to be true, that forward fins increase turning ability. On the other hand if you look at a nose-rider like a Takayama Model T, the fin, if it’s glass-on, or the fin box are set way back. That gives stability when the board is in trim and the surfer is on the nose. Picture an exaggurated design: a surfboard with a fin sticking 1 foot behind the tail of the board. There’s no way you could turn that thing. The opposite would be a board with the fin in the middle. The tail would slide sideways, pivoting around the fin. Real life fin placement is somewhere between those two extremes, but the principles still apply. Doug