How to Repair a Damaged Fin

How to Repair a Damaged Fin

First off, don’t be misled by the title. I am only talking about how to get the form back on a fin that has scraped over rocky bottom.It is impossible to repair a fin that has snapped in half.

Badly Damaged Fin

This also goes for fins that have been sailed over sandy ground a few times to many and have flattened the smooth curve to the tip. This also usually implies that the tip has been formed into a sharp point. These changes in the fin shape will greatly influence the efficiency of the fin and cause more spin outs than necessary.

Very Used Fin

Depending on how badly the fin has been damaged. If you have gone over rocks, it is very likely that the edge has split open and you can see all the individual layers of materials that make up the fin. If that is the case you have a lot of sanding to do if you use sandpaper. For the rough sanding it is best to use a rasp.


Then for the fine sanding you can use sand paper. There is a trick you can do though. If we just take the sandpaper in our hand and start scraping the edge, we will not get a good result because of the uneven surface and the small area of our fingers. What we have done at the surf center is to wrap some sandpaper around a block of wood and staple it on to make the sanding easier and faster.

Wooden Sandpaper Block For Fins

Now to the technique for getting a smooth curve on the fin again. Don’t just sand the immediate area that is damaged but the 5 cm on either side of it in long broad strokes (to get a gradual curve) moving from one side of the fin to the other every two strokes or so (to make sure the leading edge doesn’t become flat but rounded).

As for the trailing edge, here is my advice on that. Obviously a sharp edge will make for a clean separation of the water from the fin and reduce the risk of a spin out. However, do not make it so sharp as to be able to cut flesh. I have had the painful experience of accidentally kicking the fin when hastily positioning the kit for a waterstart and have to get stitches on the sole of my foot. That same fin could just as well cut another part of your body in a wipeout or a stranger in a collision.

In short, have a narrow trailing edge on the fin but not so sharp that it cuts.

Fin Trailing Edge

Spin Out – Causes and How to Avoid Them

Optin box

Spin out: the situation in which the flow of the water along the fin breaks off causing the board to slide sideways or at an angle to the sailing direction.

So there you are, planing along, flying over the water and enjoying the sensation of speed when suddenly the aft end of the board slides away from under you. The result of a spin out will vary depending on the circumstances. While just cruising it will just be a nuisance which is corrected with a little bit of technique. When wave riding it is mostly what we aim for in a cutback to get big spray, hence the reason for small fins and/or multiple fins. On the bottom turn it might cause a more precarious situation ending in a faceplant followed by a nice and thorough wash of the wave. And in slalom sailing, a spin out might result in a coma in the worst case scenario although most likely it will just cause a big splash and a scare if it isn’t avoided or corrected in time.

Why does spin out occur?

The reason for a spin out occurring is that the sideways force transmitted from the sail, through our body and onto the fin is so great that the flow of water breaks off and the back of the board is pushed to the side.

How can I avoid spin out?

There are several things that we can modify. First, in terms of equipment, it’s all about the fin. The length and angle of the fin as well as its relation to the sail size determine both the amount we can go upwind and the likelihood of a spinout.
Another deciding factor is the amount of pressure we put on the back foot and therefore on the fin.

How do I recover from a spin out?

Once the board has given way, leewards, we can correct it by putting pressure on the mastfoot with our bodyweight while pulling the back foot back to put the fin back in line of our movement, ie. in line with the flow of water.
If the fin spins out upwind (like during a gybe or a bottom turn) there isn’t really much you can do besides hope you don’t wreck your kit.

Hope this helps avoid or correct those spin outs you’re having. If you want some more information on spin outs check out this post by Tom von Alten.