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Calibrating an H5000 instrument system

Peter Gustafsson's Blur Sailing Team spend an afternoon making sure their new H5000 system is finely tuned

Dream team! Patrik Måneskiöld is the navigator on Blur, Johan Barne is a guru when it comes to instruments and data analytics, and Martin Gadman runs Happy Yachting and is the one who installed the instruments with me. We spent an afternoon getting the calibration sorted.

Above all, I wanted to get Johan’s input on the process, and the best practices he uses when racing with the pros in TP52. He helped us find sensible starting values, but the biggest lesson was another one:

Instruments and calibration are not something you do once, and then everything works. Some things are enough to do once, or maybe once when you are in a new place, but if you want to get the wind values to be reliable, you have to work on this continuously. It’s the same as everything else in our sport.

There are probably those who put a tape on the jib sheet when you were out with the sailmaker, and do not change it because you are unsure. However, once you understand what happens when you adjust the jib cars, then it both becomes more fun and you’ll sail faster.

So it’s the same with calibration. You have to dare to adjust the values ​​to make them work, and adjust back if it doesn’t. It isn’t dangerous.

The web interface on the H5000 is great for daring to do just that. No special software or difficult menu systems, but very straight forward.

Step one, and probably the most straightforward calibration, is the depth sounder. How far does the transducer sit under the waterline?

Step two, compass calibration, is also simple. Run the boat in a perfect circle at low speed. Find a spot with as little disturbance as possible. After each round of calibration, you get to know the numbers of the local magnetic field. Also, you can see the differences between different positions. We went from having it on the aft bulkhead to the forepeak. Not a big difference, but when you are fussy.

Step three, the log, took more time than expected. The sensor has a much smaller paddle wheel than the old Nexus sensor, and we have flush mounted it. It soon became clear that it showed far too little at low speeds, as the boundary layer have a considerable effect. After some tweaking, however, we managed to nail it through the table above. Prepare to spend some time getting this right.

There are a few different ways to do the calibration. What is difficult in Långedrag is that there is always a little current. However, some laps back and forth along the pier (and inside the harbor) made it possible to get good average values ​in Excel.

True wind is “the holy grail” when it comes to instruments. Getting TWD and TWS to work on every heading and not change in every tack requires a little job. Johan makes this adjustment many times in a race on TP52 Platoon. However, for amateurs like us, it might be enough to do it once in the morning before the race.

To get started we wanted to find proper basic settings, which looks very similar between different boats. Then adjust as it changes due to season and weather conditions. It is likely that these values ​​will be decreased a little during the season.

After a couple of tacks, if you can see that TWD differs between tacks, then the rule is to:

If you are lifted from tack to tack, subtract half the difference.
If headed from tack to tack, add half the difference.

That is, if I have TWD 200 on starboard, but after the tack to port the TWD is 210, so it is perceived as a shift of 10 degrees. Then I should add 5 degrees to get TWD 205 on both tacks:

There is also an auto function that we have not yet been able to try yet.

 

Here you adjust the difference between upwind and downwind, where you have to decrease the wind speed. We are almost done, and after we have analyzed more data, we’ll make the final adjustments.

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