@ScottScott - you make a good point about needing to quantify the impact of each contributing change on the ski as the water gets colder. Unfortunately that could only be done by rigging a ski with sensors to capture the empirical data.
One point I was thinking about is buoyancy is not impacted by viscosity ( the formula is ~ to density). If you let your ski float by itself on the water - where it sits depth wise will not change with colder water.
So why then do people either reduce wing angle on the fin, or move the front binding forward one notch to offset the real change in dynamics we experience?
My hypothesis is that the amount of downward force on the back of ski created by the wing is increasing with colder water.
The wing on the fin is an upside down airplane wing, just like a spoiler on a car, the faster the fluid passes over the spoiler, the more downward force it applies to the car to keep the rear wheels glued to the ground for traction.
The formulas for lift & drag are ~ to viscosity, hence the colder the water, the more it pulls the tail of the ski down into the water. So if left unchecked, your tail rides deeper.
Reducing wing angle reduces the downward force created by the wing, or if you move the binding forward a notch your counter balancing the additional negative lift, flattening the ski back out.
Fascinating stuff. I am still trying to map the water depth experience to principals/equations that explain it.