Having tried shimming with my formula foil board for a number of months and then reverting back to no shim, i've got to say, purely from my perspective that the negatives outweigh positives. The only real gain i felt was slightly lighter touch downs.

now that i've stopped using the shim again, the negatives became apparent. Downwind pitch stability is much better without. upwind speeds are easier to achieve without. Getting flight in anything other than flat water/windy conditions, well and truly better without.


obviously slalom foil is a very different game. Touchdowns doing 25+knots are going to be far more brutal than at 20knots, and you can tune things differently/more effectively when you're not having to chase upwind/downwind angles.


but what have your experiences been with shimming? Have you experienced other benefits? Was it instantaneously an improvement? Or was it something that took time to get used to and now you couldn't go with out the shim in? Did you make adjustments to other settings?


for interests sake, i was using a shim that put foil fuselage at somewhere between 1.5 to 2 degrees angle from the flat of the board. Differences are with other settings in the same position with or without the shim in.

My limited experience with them seems similar to yours. I will throw a shim on the 95cm wide board when the chop gets bad, or I'm going to see some swell 2ft or more). Makes a big difference in those conditions. But last time I was out in <1ft of swell/chop, it didn't seem to make much of a difference in upwind behavior without the shims. Wasn't having issues digging the rails or with touchdowns in that case. And the more the shim the harder it was to get going, to the point I dropped the shim and left it out in recent light winds.

When I use the board in <7.0 conditions or in hairy disorganized reflective chop, that is when I really want the shim in.

I am interested to know what foil set you are using

Starboard IQ foil (115+fuse) with a Severne hydro 100 wide foil board.

Are you talking about rake? I prefer to ride with my nose a little bit high. Just because I'm more comfortable like that! And foiling with confidence is the most important for me. Down side, maybe just a little bit harder to take off.

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Subsonic said..
Starboard IQ foil (115+fuse) with a Severne hydro 100 wide foil board.

Thanks for that, be interesting to hear from IQ users on their preferences, unfortunately not something i have any experience with.

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Vinc88 said..
Are you talking about rake? I prefer to ride with my nose a little bit high. Just because I'm more comfortable like that! And foiling with confidence is the most important for me. Down side, maybe just a little bit harder to take off.

Yep, mast rake. My set up has a little under 1degree of mast rake with out shimming, maybe taking up closer to 2 degrees was a bit much for the set up. But i'm not really feeling like i need to stick the shim back in anytime soon

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tonyk said.. Thanks for that, be interesting to hear from IQ users on their preferences, unfortunately not something i have any experience with.

Their experience is often tearing the bolt thru the roof...... so I am with Subsonic. Not worth it unless you are getting paid to win or something.

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tonyk said..

Subsonic said..
Starboard IQ foil (115+fuse) with a Severne hydro 100 wide foil board.

Thanks for that, be interesting to hear from IQ users on their preferences, unfortunately not something i have any experience with.

It's top secret!

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jusavina said..

tonyk said..

Subsonic said..
Starboard IQ foil (115+fuse) with a Severne hydro 100 wide foil board.

Thanks for that, be interesting to hear from IQ users on their preferences, unfortunately not something i have any experience with.

It's top secret!

Here's a man on IQ with inside info, but he needs to keep it in the vault until Paris is over

I think you're about right with what you're describing.
Most of the time, I use about 1.6 degree rake (1mm shim with my foil and board) with the IQfoil. More when it's windy and choppy or doing slalom and less when it's light and doing course racing.

To sum up, it's a trade of between having the nose too low, crashing hard if you touch and having the nose too high with difficulties to get on the foil in light wind and losing a tiny bit of control (because you're rig is higher up) in very strong wind.

I tried 4 degrees in very light wind and at first I could easily go on the foil by pumping harder but after a couple of races, I screwed up a tack and was too worn out to pump hard enough to take off again. You don't have that problem in strong wind.

My setting (which could be different with your foil) is:
Course racing:
Light wind: no shim or 0.5mm if choppy.
Medium wind: 1mm shim or 1.5mm if choppy.
Strong wind: 2 mm or 2.5mm if choppy.

Slalom: 2mm in light wind and 3mm medium /strong.

Like you, I prefer foiling without the shim and with the nose as low as possible but I started to have enough of cracking my board's nose with any touch down

You just have to try the different shims and find the setting where you're confident you can push without doing a catapult if you touch.

Mark above said, "Their [IQ users] experience is often tearing the bolt thru the roof...."

That is no surprise since they are shimming DT fittings. Any time you don't have tight and intimate contact of both front and back rounded tapers, you cause point loading, and you depend too much on the bolt and its connection to the roof. The DT box was not designed for this.

If you really want to shim, use the plate and dual-track method to connect foil to board. You can easily and safely use big tapered shims between plate and board to get different rake angles. No point loading this way.

I shim my mast and use around 2.4 degrees mast rake on my JP 100 course racing board for two reasons.

1, the damn thing is so wide and nose heavy that when i get hit by a gust, it shoves the board nose down onto the water going upwind which is slow.
2. I got sick of catapulting over the front constantly while going downwind, especially while racing.

It might be a bit harder in light wind but i cant seem to get above 24 knots downhill on my IQ Foil without crashing so the extra nose angle helps me stay a bit safer during touchdowns.