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

[Dean Vermeire]

Yes, I thought about that while out yesterday.  We have virtually no 
current at all, but I did go downstream and back up to compare.

On 8/3/2015 8:07 AM, Martin Rosenberg wrote:
> Please keep in mind that the knotmeter is telling you speed over water
> while the app must be telling you speed over ground. I can't believe that
> your lake currents are that strong but have you tried clocking it in
> opposite directions to see if it's still the same? If current is affecting
> your ground speed that will expose it.
> Martin Rosenberg
> "Avalon"  #823
>
> On Mon, Aug 3, 2015 at 8:59 AM, Dean Vermeire <dean at vermeire.us> wrote:
>
>> 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)
>>
>>
>