Quote:
Originally Posted by kawishiwi
I do not believe you have faintest idea what you are talking about. I was over a hundred yards away from 30+ ft cruiser today, probably doing about 6, and it threw enough wake I had to scramble to turn my boat into it so I didnt get rocked from gunwale to gunwale.
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I actually have a pretty good idea about what I'm talking about. Here's the deal, the "hull speed" (the fastest the boat can go over water before it starts to plow or climb on plane) of a boat is dependent on the length at waterline. The equation is: hull speed in knots equals 1.34 times the square root of the waterline length in feet (HS = 1.34 x √LWL). Thus, the longer the hull the faster the hull speed is. While there are certainly other factors that affect wake and true hull speed, for a given speed under hull speed, a longer boat will make less wake than a shorter boat if they have similar hull designs.
When boat operate at 2/3 of hull speed or less, they make practically no wake at all. 40 foot boats would typically have a 35 to 38 foot LWL, thus their hull speed will be around 8 knots (9.3 MPH). At 6 MPH, they are clearly running at less than 2/3 of hull speed (6.2 MPH) and not making more than a minor ripple.
The hull speed of a 10 foot PWC (assuming 9 feet LWL) is 4.6 MPH. At 6 MPH they are plowing like crazy and throwing a good size wake, pretty much like the photo in the first post on this thread...
Here's a really neat white paper on wakes, if you like physics:
https://dpipwe.tas.gov.au/Documents/...ake-151014.pdf