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FIN FUN-DAMENTALS
Fins are a very important accessory for your surfboard. Choosing the right fin for your board is crucial to how it rides and turns. As a general rule, Dilgo Surf recommends that you have 3 different fin templates (fin outline) - a pivot, all-around and raked fin. Below is a tutorial of the science behind fin shapes.
FINS 101
Size counts
As a general rule in longboarding, the size fin you select should be based on the size of your board. The size of a fin is measured from the base to the top (height). Your fin should be close the same in inches as your board is long in feet.
Board - Fin Height
9' - 9"-9.5"
9'6" - 9.5"-10"
10" - 10"-10.5"
(Photo credit: thefinbox.com)
Template/Area/Foil
The main purpose of a surfboard fin is stability side to side like the dorsal fin of a shark or dolphin or the keel on the bottom of a boat.
The outline of a fin is referred to as the template. Area is how much space an object takes. The"area" of the fin is the surface area the template. Larger fins therefore have more area. The more area
The main purpose of a surfboard fin is stability side to side like the dorsal fin of a shark or dolphin or the keel on the bottom of a boat.
The outline of a fin is referred to as the template. Area is how much space an object takes. The"area" of the fin is the surface area the template. Larger fins therefore have more area. The more area a fin has, the more hold the fin will have laterally (side to side) when riding. A fin with less area will have less hold, but will be a little faster and feel looser.
Foil is the shape and thickness of a fin. Airplanes wings have foil and affect the way a plane flies. The foil on a fin actually works towards creating drive. Drive in a fin is the forward propulsion. Water pressure on the fin creates a squeezing effect and helps propel the fin forward. Think of a fins foil like squeezing an ice cube with your fingers. Squeeze a ice cube hard enough and it will pop out of your fingers. Fins have foil, how much and where the foiled parts are - leave it to the manufacturer.
(Photo credit: trueames.com)
Pivot vs Rake
Pivot vs Rake
Pivot and raked fins move through the water under a surfboard very differently. A pivot fin is more straight up and down vs a raked fin (pictured above) in which the back edge extends backwards. Think of them like a pole vs a hockey stick. If you put a pole (pivot fin) in the water and spin it, it moves easily. If you put a hockey stick
Pivot and raked fins move through the water under a surfboard very differently. A pivot fin is more straight up and down vs a raked fin (pictured above) in which the back edge extends backwards. Think of them like a pole vs a hockey stick. If you put a pole (pivot fin) in the water and spin it, it moves easily. If you put a hockey stick (raked fin) blade down in the water and try to spin it, the surface area of the blade will make it harder to spin than a pole.
Pivot fins are favorable on a surfboard in smaller conditions and/or conditions where you need to turn fast to get into a wave. A raked fin's extended surface area makes turns more wide and drawn out. This makes raked fins more suitable for larger waves where speed of the drop gets you into position and the rake gives you lateral (side to side) hold when riding.
All fins (even pivot fins) have some degree of rake. In what we consider a raked fin, the tip of the fin extends back more than most other templates. An all around fin has characteristics of both the pivot and long raked fins. We recommend having at least one of each; a pivot, an all-around and a raked out fin.
FINS CONTINUED
Fin Placement
Fin Placement
Chances are you have a little bit of room when you install your fin to move it forward or back towards the tail. Does it matter? Yes. The fin position and the board's tail shape and rails establishes the pivot point of the board. If your fin is forward, the pivot point moves forward. This will make turning quicker, looser or easier. If y
Chances are you have a little bit of room when you install your fin to move it forward or back towards the tail. Does it matter? Yes. The fin position and the board's tail shape and rails establishes the pivot point of the board. If your fin is forward, the pivot point moves forward. This will make turning quicker, looser or easier. If you place your fin as far back towards the tail as possible, it will make turns more drawn out but will provide more hold. Start with your fin placement in the middle, try it out and then move it to meet your riding preference.
If you plan to move your fin forward or back and/or plan to try different fins, try using our toolless center fin screws. Makes moving and changing out fins easy!
2 + 1 = 3
Fin Placement
If your board has a center fin box and 2 smaller fin boxes on the side, your board is equipped with a 2+1 set-up. The "2" refers to the 2 fins on the side called side bites, the "1" is for the center fin.
If you have this configuration, you probably have a performance board. The bottom contour of the board may perform best as a 2+1 , but y
If your board has a center fin box and 2 smaller fin boxes on the side, your board is equipped with a 2+1 set-up. The "2" refers to the 2 fins on the side called side bites, the "1" is for the center fin.
If you have this configuration, you probably have a performance board. The bottom contour of the board may perform best as a 2+1 , but you can ride it as a single fin. Typical 2+1 performance boards have a double concave bottom allowing water to flow out the back of the board between the center fins and the side bites. Look at your board and see what you have. Try both and go with what feels right. Performance boards are better in big waves and tend to be faster and more manueverable. They not only have the double concave, they usually have more tail rocker (upward curve). The more rocker a board has the slower the board will paddle.
For 2+1 fin sizing, you will want a smaller center fin than if you were riding a single fin. The side bites make up for the lack of hold of a larger center fins. The center fin in a 2+1 should be 1-2 inches shorter than the board length in feet. (9" board, 7-8" fin). The side bites should be ~3-4 inches). There are sides to a side bite. The flat side of the side bite faces the center fin.
For 2+1 finplacement, forward center fins provide manueverability and back provides stability. The side bites are not movable. The also attach using 2 different style fin boxes, Futures (1 tab per fin) or FCS (2 tabs per fin).
Dilgo Surf has the set screws for both fin systems in our online surf shop.
The FLEX
The FLEX
Fin flex is a thing, but unless you a pro, the flex of a fin is not significant and will matter least in fin selection. The idea of fin flex is as you turn your board, the side kinetic (motion) energy applied to the fin from the water converts into potential (stored) energy. The tip actually bends or flexes to the side. When coming out of
Fin flex is a thing, but unless you a pro, the flex of a fin is not significant and will matter least in fin selection. The idea of fin flex is as you turn your board, the side kinetic (motion) energy applied to the fin from the water converts into potential (stored) energy. The tip actually bends or flexes to the side. When coming out of a turn the potential energy stored in the fin is released as kinetic energy adding a boost of propulsion to your ride.
There are so many options to fins. If you need help selecting a fin that is right for you and your board, send us an email.
(Photo credit: trueames.com)