Calibrating an Autohelm ST60 knotmeter

[Bob]

My knotmeter consistantly reads low when compared to various GPS handhelds. It's usually 2 to 3 knots slow even after converting kts to mph. The impellor spins easily and I dont believe is a factor. Does anyone know how to calibrate the knotmeter using the ^ and v buttons on the display? Thanks.BobS/V Thome Inn

 

[Don Alexander]

When All Else Fails Read the Manual

Regards.

 

[Pete]

calibrate the knot meter

it is a little more complicated then pressing the up and down buttons , you need to get a factor to calibrate to from running a measured distance(waypoints on gps) you realy need to have the manual to do it correctly

 

[Claude L.-Auger]

ST60 Calibration

Pete is right, it involves more than the up & down and you do have to establish a factor between 2 points with a measured distance (GPS is great for that, taking a straight run between the 2 points with and against the current), then averaging both to establish factor. Fairly simple but time consuming. When you do have the factor, then using the manual becomes a simple adjustment of the log with the factor. Log is generally calibrated at 1.00 at the factory. You will calibrate it up or down based on what your factor has been estilished at. Don't forget that what you see is always going to be your speed in the water and not your SOG. I have a manual and could possibly fax you the pages if need. just let me know. Good Luck

 

[Claude L.-Auger]

ST60 Calibration Part 2

Set your GPS in Kts and nautical miles while you're at it. And BTW, because your knotmeter calculates Speed and distance over water and the GPS does it over the ground by using satellites, the speed and distance showing on both instruments will almost always show some difference. Let me know if you need more info. Good Luck

 

[Warren Blanchard]

Knotmeter Calibration

What no one has mentioned, is that you can arbitrarily adjust the "calibration factor" to make your knotmeter read what you want it to read without having to make the measured mile runs. Assuming you know how to get your instrument into the calibration mode (press & hold the left two buttons for five seconds, I think, but better to read the manual), you then simply increase or decrease the calibration factor readout in small increments until you've got the speed you want. It may take several tries because you have to come back out of the calibration mode each time to see how the speed was affected. In my opinion, as long as there's no current, using your GPS as the speed reference should work fine. With SA turned off it's about as accurate as you can get.Warren BlanchardSV "Banana Wind"