Lake Daytime Speed Limit

[Woodsy]

Originally Posted by John Mercier

I do understand the inverse function of displacement and speed. That is why I question wave speed. A higher wave speed... even if the wave has a lower amplitude... results in a greater conservation of kinetic energy over a specified distance. That is what the scientific studies showed.
The faster boat is displacing less water mass at a higher rate of speed.

You are correct in that the faster boat (on plane) is displacing far less water at a higher rate of speed than it would at a slower speed. It is also transferring far less energy to the water.

The planing hull design is where the relationships change. Planing hulls are designed to give little resistance to the water and take advantage of hydrodynamic lifting.

The hydrodynamic lift of the hull design is what changes the wave form of the wake. When on plane there is very little displacement (relative to size & mass) very little drag (mostly the drives) and thus very little energy transferred to the water in the form of a wake. The energy is instead expended as speed.

The wake of boat on plane has very little energy transferred from the hull, so the amplitude is low, wave energy is low, and wake dissipates very quickly.

Woodsy