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Old    Jason Barber (A7X_LSV_23)      Join Date: Mar 2010       08-30-2010, 9:00 PM Reply   
Anyone got any good expanation as to why deeper water will create a bigger wake then shallower water. I know and have read everywhere that deeper water is always better... But can anyone use the terminology or mathematics behind why.
Old    Alain (ak4life)      Join Date: Nov 2003       08-30-2010, 9:27 PM Reply   
They have some formulas here: http://en.wikipedia.org/wiki/Wake -- it's all in Greek though. Enjoy.
Old    Ryan Shimabukuro (ryan_shima1)      Join Date: Sep 2002       08-30-2010, 9:49 PM Reply   
Jason, more water gets displaced in deeper water, thus creating a bigger wake. When it's shallow, it pushes off the bottom and creates a smaller wake. That's what I've been told, no actual scientific data behind it.

My friend who own's his own private lake told me that you need a minimum of 12 feet depth to maximize a wake.
Old     (Eden)      Join Date: Jul 2010       08-30-2010, 9:49 PM Reply   
Duh... everyone knows that this pattern follows from the dispersion relation of deep water waves, which is often written as,


where g is the strength of the gravity field and "deep" means that the depth is greater than half of the wavelength. This formula has two implications: first, the speed of the wave scales with the wavelength and second, the group velocity of a deep water wave is half of its phase velocity.

As a surface object moves along its path at a constant velocity v, it continuously generates a series of small disturbances corresponding to waves with a wide spectrum of wavelengths. Those waves with the longest wavelengths have phase speeds above v and simply dissipate into the surrounding water without being easily observed. Only the waves with phase speeds at or below v get amplified through the process of constructive interference and form visible shock waves.

In a medium like air, where the dispersion relation is linear, i.e.


the phase velocity c is the same for all wavelengths and the group velocity has the same value as well. The angle θ of the shock wave thus follows from simple trigonometry and can be written as,


This angle is dependent on v, and the shock wave only forms when v > c.

In deep water, however, shock waves always form even from slow-moving sources because waves with short enough wavelengths move still more slowly. These shock waves also manifest themselves at sharper angles than one would naively expect because it is group velocity that dictates the area of constructive interference and, in deep water, the group velocity is only half of the phase velocity.
Old     (Eden)      Join Date: Jul 2010       08-30-2010, 9:51 PM Reply   
just kidding... ive heard the same thing... but dont know why... I assume that with deep water, there is more water that is forced upwards to create more mass in the wake...
Old    Alan Slabaugh (alans)      Join Date: Aug 2005       08-31-2010, 4:02 AM Reply   
I always was under the impression that in deep water the displacement of the hull pushes the water straight down and then rebounds in the same direction. Versus shallow water where the water displaces downward but then hits the bottom and dissipates to the sides, effectively killing a lot the rebound.
Old    Tuneman (tuneman)      Join Date: Mar 2002       08-31-2010, 6:02 AM Reply   
Alan wins the grand prize.
Old    A-dub (behindtheboat)      Join Date: Aug 2006       08-31-2010, 6:15 AM Reply   
and after 10-12 ft it really doesn't matter

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