I wrote this some time ago for ESM magazine. It’s a bit simplistic but these are the findijngs I’ve found with fins over the years.
CHANGING FINS
INTERCHANGEABLE FINS
The concept of interchangeable fins is probably almost as old as fins themselves. With the exception of a short period during the Ô70s fins for the most part have been glassed on. Now with the advent of the first truly lightweight dependable fin box system for thrusters, made by numerous fin companies fin systems, we can now take advantage true interchangeability.
ARRANGING FIN SETS
Arranging fins in sets that make sense to your individual surfing style and to changing conditions can take a lot patience and experience. The purpose of this paper is to make you aware of the significant advantages of interchangeable fins and to help you get a feel for how fins work.
HOW FINS WORK
The front fins create lift, facilitate faster turning and give the board more speed out of turns. But they also slow down rail to rail transition giving the board a ÒstickyÓ feeling like its about to catch an edge if theyÕre too big.
The back fin is for control. It has the effect of pulling the tail of the board down and anchoring it to the wave face. The bigger the fin is and/or the further the fin is placed towards the tail of the board the stronger the anchoring effect. The disadvantage is they can also create drag and make the board bog.
WAVE SIZE
Small waves are generally slower than large waves. Therefore for small waves you will need as much lift and maneuverability as possible while control will not be as much of a concern. Large side fins with a small trailer fin will create this effect. For large waves you will generally want more control and need less lift. So you will probably want more back fin and possibly less front fin than you used in small waves.
WAVE SHAPE
Flat faced or mushy waves call for a board with more lift and glide. Hollow waves call for quick rail to rail transition and good hold. For mushy waves a regular set of side fins with a small trailer fin will probably work better. For hollow waves small side fins will allow fast rail to rail transition and a larger back fin will anchor the tail securely in those steep sections.
SURFER SIZE
Larger surfers should generally use larger fins. Smaller guys arenÕt generally as powerful and need less fin. This is mostly regarding the front fins.
TROUBLE SHOOTING Q&A
Q: My board spins out off the top and slides out on cut backs. Should I use bigger fins?
A: A larger back fin will help your hold but your problem is probably that your side fins are too big. First try a smaller set of side fins and if thats too loose and slides to much add a bigger back fin.
Q: When IÕm cutting back my board seems to stick right in the middle of the turn. I canÕt seem to complete a full roundhouse. What gives?
A: The problem is that when your turn is in transition from a carving turn at the beginning of the cutback to a pivot at the mid point of the turn, the fins are fighting each other. Fins must work as a unit. A smaller back fin will restore harmony and solve your problem.
Q: Help!! I canÕt seem to get my board planing. IÕm always bogging and going slow. My friends donÕt seem to have this problem. Please help me.
A: You have a very common problem to which there are two possible solutions. The first solution is a smaller back fin. This will reduce drag and enable the board to plane more easily. If this doesnÕt solve your problem it probably means your board is too small. Ask yourself these Questions:
(1) Are you bigger than your friends and trying to ride the same size boards they do? (2) Do you have trouble catching waves and when you do catch them do you have trouble getting up? If you answered yes to either of these questions then your board just maybe too small. There is nothing wrong with riding a board that is the correct size for you regardless of what your friends may ride. After all if your friend wears a set of size 28 pants IÕm sure he wouldnÕt expect you to wear the same size even though your waist is 32. Surfboards arenÕt any different. Get yourself enough board!
Q: IÕve been riding my board with just the side fins and it seems to work fine. Is this O.K.?
A: You bet it is. IÕm for any fin set up that works for you. In fact there are a number of really fine surfers like John Holeman who use this set up in small waves all the time. You may want to keep a trailer fin around for those hollow days though.
Q: IÕm using a regular set of thruster fins in my board for bigger days and I just canÕt seem to make it around some of the mushy sections that I feel I should. Could you suggest a possible solution?
A: A lot of surf spots here on the U.S. mainland tend to get mushier and more flat faced as they get bigger. If this is the case at your local break then the solution would be to use a smaller back fin that will reduce drag allow the board to build speed more easily and glide a bit more. This will also allow the board to have a bit more down the line speed, allow it to get a little further onto the flats in front of the wave and get you around those sections.
Q: I like to noseride but my board pearls and sometimes the fin comes out when IÕm riding forward. Can fins help me noseride better?
A: You bet. Noseriding can be improved by using a larger back fin. This will hold down the tail while you camp out on the nose.
Q: When IÕm tube riding hollow waves I always seem to ride down into the lip and get crushed. Its kind of frustrating and hurts too. What can I do?
A: Your fins need to hold you higher in the pocket so you wonÕt slide down and get crushed anymore. Increase the size of your back fin.