scott allen wrote:
Hello. A physics question:
Using the hand-held floating ball Dwyer wind meter.
If you use the dwyer wind meter on a moving boat (pointed in the direction of movement), will it show the speed of the boat?
or is there a mix of wind and boat speed and it will not indicate true boat speed?
or does it show the speed of apparent wind?
and would it mater which point of sail is underway? as I can imagine straight downwind would be accurately measurable with the hand held meter.
but it seems other points of sail would not be measurable with the meter, do to a mix of wind and boat speed.
any help? Scott
You need a compass.
While your boat is stopped use your wind meter to measure the true wind velocity.
Use your compass to measure the direction of the true wind.
Next take the apparent wind velocity and direction while you are sailing.
Find the angle between the true wind and the apparent wind.
Take your apparent wind velocity and multiply it by the sine of the angle to get some number (call it Y).
Take your apparent wind velocity and multiply it by the cosine of the angle to get some number, then subract the true wind velocity from that number to get another number (call it X).
Add X to Y and then take the square root of that number. The result is you boat speed.
I think it will be hart to get good measurements but it should be a fun project.