[C320-list] Speed Increase by Installing App on Smart Phone - How to calibrate knotmeter?

[Dean Vermeire]

First of all, I should point out that after 40 years of sailing, our 
Catalina 320 (which we have had for 4 years) is our first boat with 
speed and wind instruments.  Electronics aren't all that necessary on a 
lake in Kansas.

So, when I see that I am doing about 2.2 knots in 6-10 knots of breeze 
on a beam reach, or motoring at 2.5 knots with the yanmar humming along 
at 2500 RPM, I really don't have anything to compare to.  And then, some 
of you folks talk about motoring at 6-7 knots, so I just figure that I 
should switch out the 2-blade prop for a 3-blade.  But when you talk 
about sailing at 6-7 knots or more, and the most I have been able to get 
out of her is 5 knots with the Asym flying in a good breeze, I start 
thinking one of two things - either the knotmeter is lying to me, or I suck.

Yesterday, I downloaded a simple GPS app, "SailDroid", to my phone. My 
knotmeter says 2.2 knots.  The phone says 4.5!  This is not definitive 
proof, but I'm going to say that I do not suck!

It is amazing how it feels like you are going faster, just because some 
widget thinks you are.  :)

The paddlewheel sending unit is only 2 years old.  Is there a way to 
calibrate the knotmeter (ST-60)?

Thanks,
Dean Vermeire
Moonstruck II (#847)