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.
This article is a translation of this one from june 2018.
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:
And yes, I have set up a cheat sheet :-)
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. For now.
Leeway is a guessed factor. Can be measured in slightly different ways, but right now we think this is good enough.
The integration with Expedition is relatively straight forward. You either choose Hlink (serial over USB) or Websocket (over WiFi or network) which is the preferred method. Here you should be able to exchange all data, starting line, countdown and much more.
It is easy to set up which data you want to send to the H5000 to display on the mast or cockpit displays. H5000 automatically finds this data as USER, and everything comes up with the right labels, damping and more. Easy.
The H5000 provides a good overview of where data comes from. One often has several units that can give the same values. Here is a list of the data available in the system right now:
Aft Depth 2.570212 m
Air Temperature 29 °C
Altitude -2.2 m
Analogue Channel 1 0.092
Analogue Channel 2 0.087
Analogue Channel 3 0.092
Analogue Channel 4 0.092
Apparent Wind Angle -42.440735 °
Apparent Wind Speed 4.837355 kn
Average True Wind Direction 243.4 °M
Barometric Pressure 1015 mb
Bias Advantage 0.079
Bias Advantage BL 13.3
Blue Phase 1.68
Boat Speed 0 kn
Boat Speed Correction 0.00 kn
Bow Position Latitude 57°040.094′ N
Bow Position Longitude 011°050.708′ E
Commanded Rudder Angle 0 °
Corrected MWA -54 °
Corrected MWS 5.33
Course 288.6 °M
Course Over Ground 278.459473 °M
Dead Reckoning Bearing 356.6 °M
Dead Reckoning Distance 0.00 NM
Depth 2.570294 m
Depth Offset 0.4 m
Distance Behind Start Line 0.05 NM
Distance Behind Start Line (Boat Lengths) 8.23
Distance To Start Line 0.05 NM
Distance To Start Line (Boat Lengths) 8.23
Geoidal Seperation 0.02 NM
GPS Fix Type 3.00
GPS Position Latitude 57°040.093′ N
GPS Position Longitude 011°050.715′ E
Green Phase 4.53
Heading 288.723145 °M
Heading Opposite Tack 203.8 °M
Heel -0.134003 °
Log 484.2 NM
Magnetic Variation 3 °
MARK TM 8.35
Measured Boat Speed 0.00 kn
Measured Boat Speed Port 0.00 kn
Measured Wind Angle -54 °
Measured Wind Speed 5.3 kn
Opposite Tack COG 044.8 °M
Opposite Tack Target Heading 203.4 °M
Optimum Wind Angle 1 °
Orig TWA -53.634
Orig TWD 247
Orig TWS 5.33
Pitch Rate 0.0 °/sec
Polar Performance 0 %
Polar Speed 4.46 kn
POLBSP PC 0.000
Position Error 0.00 NM
Position Integrity 0.000
Position Quality 1.00
Race Timer 00:05:00 hrs
Rate of Turn 0.2 °/sec
Red Phase 1.28
Roll Rate 0.0 °/sec
Rudder Angle 1 °
Satellites in View 12.0
SDGPS Status 0.000
Sea Temperature 20.9 °C
Signed Leeway Angle 0 °
Signed Leeway Angle 0 °
Speed Over Ground 0 kn
Speed Through Water 0.00 kn
Start Line Bearing 195.2 °M
Start Line Bearing To Port 233.7 °M
Start Line Bearing To Starboard 338.8 °M
Start Line Bias -39 °
Start Line Distance To Port 0.08 NM
Start Line Distance To Port (Boat Lengths) 13.2
Start Line Distance To Starboard 0.08 NM
Start Line Distance To Starboard (Boat Lengths) 13.8
Start Line Port Position Latitude 57°040.052′ N
Start Line Port Position Longitude 011°050.586′ E
Start Line Starboard Position Latitude 57°040.172′ N
Start Line Starboard Position Longitude 011°050.661′ E
TARG BSPTARG BSP 4.66
Target Boat Speed 4.67 kn
Target TWA -43 °
Tide Rate 0.000001 kn
Tide Set 356.619537 °M
TM ON P 6.09
TM ON S 2.26
Trim -0.269562 °
Trip 1 Distance 0.00 NM
Trip 1 Speed Avg 0.00 kn
Trip 1 Speed Max 0.00 kn
Trip 1 Time 00:00:00 hrs
Trip 2 Distance 0.00 NM
Trip 2 Speed Avg 0.00 kn
Trip 2 Speed Max 0.00 kn
Trip 2 Time 00:00:00 hrs
True Wind Angle -42.395828 °
True Wind Direction 246.323425 °M
True Wind Speed 4.903689 kn
TWA Correction 8 °
TWS Correction -0.423
Uncorrected Log 1 0.00 NM
UTC Date Sun Jun 3 2018
UTC Time 09:40:35 hrs
Velocity Made Good 0.00 kn
VMG Performance 0 %
Wind Angle to Mast -53 °
Wind Lift -6 °
Wind Phase 6 °