All Slalom Skiers Should Own a Caliper

water ski fin measuring caliper

It’s not unusual to find an avid skier with their own 8″ caliper tucked into their water ski gear bag. But this sight should be a lot more common than it is. In fact, I believe everyone who has a high-end slalom ski should own a caliper. It should be as much a part of every skiing enthusiast’s equipment as a vest and gloves.

The reason is that all high-end skis have fully adjustable fins; and wherever there’s a possibility for adjustment, there’s also a possibility things are not correctly adjusted. A fin only has to be out of adjustment by a few thousandths of an inch before the behavior of the ski is affected, and most skis I measure are out by substantially more than this.

fin tuning setting placement adjustment Mitutoyo 500-753-10 8" water ski caliper
Mitutoyo 500-753-10 Waterproof Digital Caliper—the gold standard of calipers for water skiers

Even if you have no intention of custom-tuning your ski, it’s still important that you ensure your fin is set to factory recommended measurements, and that it hasn’t subsequently been knocked out of spec. Think of checking your fin’s location throughout the season as being similar to maintaining proper air pressure in your tires.

We can’t assume that a brand new ski has a properly mounted fin either. In fact, they are almost never where they should be. Mounting the fin with precision can be tedious and time-consuming work. So while most, not all, manufacturers try to mount the fins fairly close to their own recommended numbers, they’re usually only close at best. To be fair, close is probably good enough for most recreational skiers—but actually measuring it is the only one way to find out if someone else’s idea of close is close enough for you.

fin tuning setting placement adjustment Harbor Freight 8" water ski caliper
A Harbor Freight Caliper is less expensive than a cheap set of water ski gloves

Improper fin placement isn’t the only variable working against the new-ski experience either. The location of the binding inserts fore and aft on the ski isn’t standardized among ski manufacturers. This means when a skier mixes ski and binding brands, a common and sound practice, the middle holes in the binding plate usually don’t put the bindings on that ski’s factory recommended location. A guesstimate of wing angle completes the average setup. Now the bindings, fin, and wing are all in the wrong place, and the skier has about $2,000 invested in a state-of-the-art ski with a setup that’s more likely to be awkward than fantastic.

The wing is an easy fix. If you are a relatively advanced skier, you can easily tell if your ski needs more or less wing-drag regardless of actual wing angle; and you probably have a set of wing gauges anyway. If you are a novice skier, you should probably be skiing with the wing off (a good subject for another post). The binding location can be properly set with a common household tape measure. So that leaves the caliper as the most important tool missing in most skier’s gear bags.

To mount a fin in the correct position, it should be measured to within one one-thousandths of an inch (.001″) in all three dimensions: fin length, fin depth, and distance from tail. The only way to accurately take these measurements is with either a dial or digital caliper; even the very nicest ruler just won’t cut it. It doesn’t have to be an expensive caliper, but it’s important that you know how to use it correctly so you get consistent and accurate measurements.

fin tuning setting placement adjustment water ski slot caliper
A slot-caliper can be slightly easier to use for some, but delivers different measurements than the more industry-standard style of calipers shown above. Note the slot cut into the head and lack of notches in the base of the jaws.

If you are lucky enough to live near a reputable ski shop that specializes in slalom skis, you can get your ski set up or checked there. But even then, it’s good to be able to measure your fin yourself out at the lake to make sure nothing has been knocked out of position by an accidental bump.

It doesn’t matter if you are a complete beginner or an advanced skier, your ski’s behavior is affected by the way it’s set up. So make sure your ski gets set up properly to begin with, and that things stay where they should throughout the season. If you don’t have handy access to a caliper, it’s time to get one. Get a nice one if you are going to use it a lot, but a cheap one will get the job done. Either way, a caliper should be considered an essential piece of your ski gear.

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