Difference between ground speed and water speed?

was out playing with my 332c and was wondering what the main difference is in the two speeds. 1.8 mph in ground speed was only less than half of that shown for water speed. Whats the skinny? Thanks

Not sure what kind of sensors that you have, but speed over ground is true speed, as measure by a gps. Speed in relation to water can be more variable, depending on currents, etc. You could be going 5 mph on the gps, but your speed in relation to the water might only be 3mph if you are traveling with the current. Maybe 7mph if you are against it (assuming a ~ 2mph current)

Also, many times the “water wheel” speed sensors aren’t entirely accurate, so they almost always differ from gps speed by a little bit. I’d trust the gps unless you know there is a noticable current.

There is almost always some sort of current in whatever body of water you are on depending on conditions (including lakes.) Lakes currents actually can be quite comples, depending on wind speed, direction, coriolis effect, etc… Great lakes have amazing currents, a lot of guys buy speed sensors to measure actually speed at the cannonball, which takes into account current speed (with or against)

Actually…
when in a current, going with the current is going to be a higher GS than the WS and up current WS will be higher than GS.
BUT… the reason it was developed is to take into account the dictance traveled up a wave and down a wave. U loose speed up a wave and gain down a wave not to mention the Pathagream therom that an angle (wave) is longer than the base (ground or sea floor)
EX. gps might say GS is .70 and WS .85 because going up the wave and down the wave was more distance than across the base. Walking over a pyramid takes longer than it does to walk one side. Which is the same as( bernuli’s law i think it is) that deals with lift from an air plane wing.
but that is what i wave been taught…

Chuncker?

Did you just say a gps is more accurate than a water wheel speed indicator?

gotcha Thanks guys!

Quote:

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bernuli’s law i think it is

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bernuli’s law actually refers to the flow of fluid. Ok, Ok… I really didn’t have a clue, but it was easy to find. I think this bernuli fellow lives down the street from me. His “fuild flow” begins on Friday night and ends sometime Sunday, in the summer time….. usually face down in the yard.

i’m sure he lives by me