pro tip: Fin Shim

by Graham

Loose fins are not good. They slow down the board and make its movements unpredictable. For the last week, I’ve unknowingly been sailing with a loose fin and therefore was falling more than normal. Check your fins for any side-to-side movement. There should be none.

Luckily, fixing a loose fin is really easy. All you need to do is put a shim on it. Here is how (click on photos for larger versions):

1) You will need some film to make the shim and scissors to cut the film into the right shape. The Ezzy sailbags have sample squares of the film used in the sail, and I make my shims from these squares because they work perfectly and are always at hand. It is not necessary to use a film with an internal yarn (like a scrim or X-ply) but it will mean that the shim will last longer.

You'll need scissors and some film in addition to the fin and board.


Using a piece of film with yarns (scrim, or X-ply) means the shim will last longer..


2) Cut the film to make a piece that has wideness a little more than a finger width and a length long enough to wrap around the bottom of the fin. This is your shim. But make sure that the shim is not so long that it extends beyond the bottom part of the fin when in the board.

Cut the film to get a piece that wraps around the base of the fin.


3) With the screw tab already in the right place in the fin box, place the shim across the fin box slot so that it is divided by it into equal parts. Ideally, The shim should be around the center or front of the fin. Put the fin in the right position (so that it will come on top of the screw tab) and push down on the fin gently enough that the shim does not slide into a different position.

Push down on the fin with the shim in place over the slot.


With the shim wrapped evenly around the base, push the fin in the board.


Push down on the fin gently but firmly.


4) Push the fin all the way in. The shim should provide enough support so that the fin is no longer loose. It is important that the shim is not visible because if it is sticking out of the fin slot, it is disrupting the water flow around the fin’s foil. The screw tab should be directly under the screw hole. Screw in the fin and you’re ready to hit the water!

Push the fin into the slot so that it is flush with the board and the shim is not sticking out.


Ask questions in the comments.

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