November 2013 Issue
Table of Contents
Where Credit Is Due
Mailport: November 2013
When you tested the Garmin Quatix sailing watch (PS, August 2013), how was your test of course over ground (COG) readings? I am asking because my Quatix gives COG +/- 5 degrees, even when walking on a straight line. Compared to my boatís electronic compass and GPS, the Quatix is having trouble showing a damped output. Using the Tack Assist or Virtual Start-line is impossible because the output is jumping up and down.
Juno, Scan-kap 99
Marselisborg Havn, Denmark
We have been using the watch for months without any issues, but we do have some suggestions for you. The first is to check that WAAS (Wide Area Augmentation System) is enabled. This is not a default setting, because it uses a little more battery power. Selecting this option will enable the use of EGNOS (European Geostationary Navigation Overlay Service), improving the accuracy of the GPS fix. A good EGNOS fix can have an accuracy of +/- 6 feet or better. The other suggestion is to recalibrate the compass. Doing these two steps should resolve your issue. Garmin also suggests that when the GPS is first turned on, keep the watch stationary for a few minutes to ensure a solid fix.
The Quatix is doing GPS fixes at a 10-Hz rate. Thatís 10 times per second. The average person walks at 3.1 mph. That is 273 feet per minute, 4.55 feet per second, or 5.4 inches per GPS fix. Heading is calculated every GPS cycle. Just waving your arm can create a new heading that might be 180 degrees different from the previous heading. Because of this, the COG is an average of the calculated heading data. This smoothing of the data causes all GPS unitís COG to be slightly behind the curve when the direction of travel is changing. The more steady the direction of travel, the closer the COG reading will be to the compass, if properly calibrated. This is exactly the same issue boat owners have. Itís typically close, but not perfect. Also, keep in mind that the Quatix compass, like all compasses, is affected by ferrous metals and magnets.
Editorís note: Early versions of the Quatix were voluntarily recalled after one report of a hot-battery safety issue. This problem has been corrected in current Quatix stocks. Read more about the recall on the Garmin website, www.garmin.com.