The more testing and tuning I do, the more I realize how critical it is to fine-tune binding placement to control smear—especially through the middle of the turn. If your hips are less than 12″ above the water around the ball, your ski will be rolled up onto such a steep edge that the fin has very little effect. This leaves the length of tail behind your bindings in almost complete control of smear (ski rotation or tail slide). The fin still has an effect, but more like a trim tab than a rudder.
If you turn with your hips within 12″ of the water and your ski is over-rotating or over-turning through the finish of turns (over-smear), move your bindings forward to increase your ski’s tail area. More tail area resists smear, making it harder for the ski to over-rotate around the ball. If the ski is under-smearing through the turn, making your turns too big and round, tending to finish with insufficient angle, move your bindings back to increase tail loading.
To some, moving the bindings back to get tighter turns seems counter-intuitive. Exaggeration can help make the effects of binding location more obvious. If you mounted your bindings all the way back over the fin block, the gigantic tip would bite hard whenever it engaged the water, and the centrifugal force of your entire weight over the short, skinny tail would make the the ski spin out. You’d be constantly battling tip-grab unless you kept most of the tip out of the water.
Similarly, if you mounted your bindings right up over the tip, the long tail wouldn’t smear at all making turns horribly long and wide. Attempts to force the ski to turn would lead to your weight overwhelming what little tip there is, and it would simply wash out. You’d never complete a turn with enough angle to get across the course to the next ball.
These relationships govern the normal range of binding adjustments too. When moving forward to reduce over-smear, some skis may not be capable of generating enough tip support and the tip will wash out. Tips with a lot of rocker may start grabbing by surprise. In cases like these, move as far forward as possible before tip issues start getting in the way, THEN increase fin area to tame any remaining over-smear. Again, think of the fin as more of a trim tab for smear than as a rudder. Focus mostly on the offside turns because onside turns can be distorted by too much rear leg action.
Fine tuning binding placement means being able to move your bindings 1/8″ or less at a time. So if your binding system doesn’t feature a fine-tuned mounting system or Dual Lock, and if you are shortening the rope in a ski course, you should seriously consider installing Mikro-Just, at least on your front binding plate.
Most falls happen around the backside of the ball, and a lot of these falls can be avoided if your ski is smearing just the right amount. Too much smear and the ski over-turns, creating unsustainable angle and rope tension. Not enough smear and you are trying to slalom a school bus. Fin setup effects mostly the pre-turn and the way the ski the ski hooks up as it rolls out of the finish of turns. But binding location has a tremendous effect on the way your ski smears most of the way through hard, fast, tight, steeply banked turns.
Use the right tool for the job, binding location, when adjusting your ski’s tail behavior at extreme lean angles.