If you are wind foiling, sooner or later (probably sooner), you will come to the point when you ask yourself why the board sometimes feels sticky (not lifting up so easily), why you sometimes crash when you touch the tip of the small wave, and overall why your foiling is not so smooth as you see in most of the advanced foilers out there.

The reason could be (and many times is) not enough mast foil rake. That is, not enough inclination degree between the board and the fuselage of the foil. I do not intend to explain in detail what is mast foil rake and why it is so important for smooth foiling. You can find out about that from more experienced foilers. For example, a nice video by Michele Becker: “Make Your Foiling Much Smoother – Use More Rake” or an excellent article by Marco Boone: “Mast Rake Explained”.

In short, the mast rake can be zero when the fuselage is in line with the bottom of the board. That will happen in most cases when you use foil-ready boards with tuttle boxes and support plates, and also, some foils can be designed to deliver optimum performance with zero rake.

The mast rake can be in minus ( a degree or two). You should avoid that situation unless you have a very good reason to foil like that. What that reason could be is beyond my understanding at the moment. In most cases, if the foil rake is minus, the board will feel sticky because, while foiling, the nose of the board is pointing down.

What you want is mast rake in plus up to… well, the opinions differ, and you should probably find what is best for you, but usual numbers are from 2 to 5 degrees.

Inclination Tool

Last season, after one complaint to a much more experienced foiler that my SB IQ board felt sticky, I received advice to measure the rake with a smartphone application (yes, you can do that), and if it is less than 2 degrees, to try to increase it by inserting pieces of hard plastic (for example pieces of old credit card or something like that). I tried, but the process was troublesome since I am not inclined to be handy with such things.

That is why for this season, I equipped myself with a specialized inclination tool and a set of foil rake shims!

I bought the inclination tool HERE.

It is a small and practical device with large digital numbers. Easy to use and very precise. By pressing the button, you can set the anchor inclination. That would be the bottom of your board near the mast. When you place the tool on another surface, it will show zero if that surface is parallel to the bottom of the board. So, the next step is to place the tool on the fuselage above the mast.

As you can see, my mast rake is 2,54 degrees in plus without adjustment. That is quite good by itself. I don’t know if this is board-specific or Starboard made IQ foil masts with the intention to deliver a +2 degrees rake. Anyway, my board feels sticky with that rake, and the foiling is not as smooth as I would like.

Rake Shims

So, I want to increase the mast rake, but in order to avoid improvising, I bought a set of “rake shims”. A rake shim is a piece of plastic fitting in a foil box between the top of the mast and the board. Since that piece of plastic is cut to a specific degree, it will slightly tilt the mast and increase the rake.

You can find a few sets of mast rake shims around, but I bought my HERE.

Placing the shim in the foil box is easy. You drop it inside and don’t have to adjust anything because the dimensions fit, and the holes are in the right place.

In this particular set, shims are from 0,5 to 3,5 degrees. But you can combine them if you so wish. For example, if you have rake zero and want to increase it to 4,0, you can combine 2,5 and 1,5 to get 4,0. If, for any reason, you want the rake in minus, you can turn the shims on the other side to tilt the back side of the mast. (Well, like I said, I don’t know why you would want something like this, but the possibility is here.)

One warning, though. If you use a bigger shim, you might need longer screws! That little “catch” is why I have to stick with just a smaller adjustment of 1 degree because, for a larger adjustment, I need longer screws which I don’t have at the moment.

Would the shim really increase the rake as it is supposed to do? It did, but not quite precise. I put a 1-degree shim in the foil box and measured the rake.

As you can see, the rake is now 3,33. As you remember, originally, without the shim, it was 2,54.

So, my 1-degree shim increased the rake for 0,79 degrees. Well, good enough (probably).

I’ll let you know what will happen with other shim sizes when I get hold of longer screws. 😊

The first try on the water. South wind, 12-14 knots. SB IQ board and foil, Loftsails Skyscape 9,0.

Indeed – the board feels less sticky and more stable in flight! I have to try it more and experiment a little with different rakes. But, judging by the first experience, mast rake is truly something every foiler has to take care of. The impact on foiling could be quite significant.

About the Author: Adrian

Author and writer of more than fifty books, teacher, lecturer, explorer of consciousness, avid windsurfer, and lover of outdoor activities. He’ll write mostly about windsurfing on fin and foil, spot reviews, and camping equipment.
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