Slalom Skiing Instructional - Fin Adjustment

Author: Joel Wing   Date Posted:26 September 2016 

So, you have taken home a new ski from the shop. Skis from mid-level to Pro level now come standard with an adjustable fin, but what does it do? Why does it adjust? You might have been attacking the slalom course for years and have some idea that it can help, but are too scared to make any changes because you don’t know what they might do, or how it will help or hinder your own skiing?

There are some important things to mention before we start getting into the details of each setting and what they do:

Keep A Diary!

The first thing I must stress is that you need to keep track of your changes and what they do to your skiing. Because if you make a series of changes and they aren’t helping, you can easily go back to some earlier settings when you ski was working really well. If you don’t keep a record of your settings, you won’t be able to do this, leaving you with a ski you don’t like with no way of getting it back to when you liked it!

 

Tools of the trade:

Before we start we need a few important tools:

Wing Angle Gauge set:

These allow you to measure your wing angle regardless of any changes you make to the tip of the fin (this will be explained later). The indicators printed on the fin will not be accurate if we start moving the front of the fin higher or lower.

8” Calipers:

These allow us to take the measurements we need. Adjustments of as little as 0.001” can be noticeable to good skiers, so accuracy is very important.

Allen Key:

A nice T- handle allen key makes the adjustments much easier, you may need multiple sizes depending on the grub screws for your particular fin & perhaps for the wing.

 

OK, so let’s get into the nitty- gritty, here is an explanation of each of the adjustments we can make to the fin & what impact they make on the skis performance. As so much of the established knowledge has come from the USA, it is standard to speak in inches for fin adjustments.

 

You may notice that some adjustments can create the same effects. It is important to consider all the aspects of your skiing and choose the best adjustment for the changes you are looking to make. Remember, by keeping the diary, you can try one adjustment, and if it doesn’t work, you can always put it back where it was & try another. I recommend trying adjustments in the vicinity of 0.02- 0.04” each time. Feel free to try larger adjustments, however be prepared to take them back if you are experiencing the negative effects of these adjustments.

 

Distance From Tail (DFT):

This measurement is taken from the tail of the ski to the back edge of the fin. This should be somewhere in the vicinity of 0.6- 0.9”. Moving the fin forward or back effectively makes the ski feel longer or shorter. A low DFT measurement (the fin being further back on the ski) makes the ski act longer. By increasing the distance of the bindings to the fin means the skier has more leverage, and can therefore maintain more angle out of the turn, making the ski feel faster. On the flip-side, though, this longer distance between the bindings and fin mean the ski turns less freely.

DFT in brief:  If your ski is turning too hard but isn’t accelerating, or isn’t as fast as you would like, try moving the fin back. If it is plenty fast, but is not finishing the turn, perhaps moving the fin forward is the answer.

Length (L):

This is the measurement taken along the fin where it comes out of the ski. This measurement should be in the vicinity of 6.6- 6.9” (hence the requirement for the 8” calipers). This is also called the tip measurement, as basically you are moving the tip up & down to increase the length of the fin. Some people might say that you are adding or taking away tip when you are increasing or decreasing the length. What does it do? Increasing the length of the fin will effectively increase the surface area of the fin. This increases drag, and hence increases the tip pressure, basically feeling like the tip of the ski rides lower with a longer fin. This is especially noticeable on the ‘off side’ (turns out the left side of the wake for left foot forward skiers, opposite for righties).

Length in Brief: If the tip of your ski is riding too deep on your off side turn, consider decreasing the length of your fin, if it is riding too high, perhaps increasing the length is for you.

Depth (D):

An obvious one, it’s the depth of the fin measured from the base of the ski to the deepest part of the fin. This measurement will be somewhere around 2.5”. Changes in the fins depth can change the largest number of factors influencing the performance of the ski.  Increasing the depth of your fin increases the power you have against the boat. This can both help your ski to accelerate out of the turn by making it easier to maintain the angle generated, as well as giving you more power after the wakes, increasing your width coming into the turn. A deep fin will also decrease ‘tail blowout’, where the fin comes out of the water at the end of the turn. A deep fin sounds great, right? The downside is a ski that will not turn as readily as the fin will not slide through the water as easily at the end of the turn. This can also appear through the tip of the ski rising dramatically through the end of the turn (wheelie).

Depth in brief: Increase your depth until you notice the ski is not turning as well as it did, or your ski is rising (doing a ‘wheelie’) at the end of the turn. If you are having trouble turning the ski, decrease the depth until you notice the tail of the ski blowing out of the water too frequently.

Wing angle:

This is probably the most obvious adjustment that many of you may have already tried. The theories around wing angle have traditionally been that increased angle causes greater deceleration into the turn, reducing slack rope (a good thing). However, too much angle will cause a skier without strong body position to break at the waist at the end of the turn. This led us for many years to discourage intermediate level skiers from using the wing at all. Recently thinking has been more towards intermediate level skiers using the wing, perhaps with a little less angle that advanced skiers. The skis have been designed using the wing, plus it also increases the hold of the fin in the water through the turn, decreasing tail blowout. Too much angle on the wing can also have detrimental effects related to the extra drag, these are less acceleration out of the turn, and, probably more noticeably, decreased width as your ski is slowed down too quickly after the wakes during the outward ski trajectory before the turn.

Wing in brief: Not getting wide enough? Ski feeling slow? Breaking at the waist at the end of the turn? Perhaps you need to try less wing angle. Ski feeling too fast at the end of the turn causing slack rope, or is the tail blowing out? Maybe more wing angle is you.

 

So, there is fin adjustment in brief, please note that binding placement has a big effect on ski characteristics, however I think that is best left for another article. There is more information available in the internet, otherwise book into one of the quality waterski schools around Australia and they will be able to help you to get the most out of your ski.

 

Joel owns & runs his own Waterski & Wakeboard School on the Gold Coast, ‘Wings Watersports’. He is sponsored by Wing Wetsuits, Malibu Boats, KD Skis & Advantage Ropes.


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