Nexus FDX-kit - Page 38

NexusRace SW English
37
Starboard tack
TWA 38.5 degrees
TWD 52 degrees
Difference in TWD
123 – 52 = 71
TWA port + TWA stb
38.5 + 38.5 = 77
This means that the tacking angle is 71 degrees but the wind angle says 77 degrees.
That is 6 degrees too much (77-71).
In order to correct this, we enter -3 degrees (6 degrees divided by two) to both port and
starboard.
This procedure has to be done for every wind speed. If you have done it for 12 and 16
knots, it is most likely that the correction for 14 knots is somewhere in between the
values for 12 and 16. It is a good idea to keep a ledger of which values you have
tested and which values you have estimated.
Table for TWS
TWS
TWA
Corr %
TWA
Corr %
TWA
Corr %
TWA
Corr %
TWA
Corr %
6
0
0
45
0
90
-4
135
-7
180
-11
8
0
0
45
0
90
-3
135
-6
180
-10
10
0
0
45
0
90
-3
135
-6
180
-10
12
0
0
45
0
90
-2
135
-5
180
-9
14
0
0
45
0
90
-2
135
-4
180
-8
16
0
0
45
0
90
-1
135
-4
180
-8
18
0
0
45
0
90
-1
135
-3
180
-7
20
0
0
45
0
90
-1
135
-3
180
-6
The table for TWS is mainly used to correct for up wash. The up wash is most
dominant on down wind and has also a stronger influence at low wind speed.