Units: rad (Radian)
Description: Leeway Angle derived from the longitudinal and transverse speeds through the water
For sail boat performance calculations leeway derived by wind force is needed.
first one is for current (only)
second could be for new transducers measuring longitudinal and transverse speeds.
(If someone doesn't have this kind of transducer leeway is calculated by a formula)
There is written for the ("new") LWY sentence (which exists in NMEA2000 too):
This Nautical Leeway Angle is used primarily in the sailing segment of the maritime industry and may differ from oceanographic or scientific definitions of Leeway.
*$--LWY,A,x.xhh**
"Performance" is calculated in reference to water, where current doesn't matter.
So I believe, that the definition of Signal K PerformanceLeeway is wrong and should be changed.
For calculations of laylines, reaching a mark etc. a new Signal K definition could be declared which takes leeway AND current into account.
For leeway I found two Signal K expressions:
/vessels//performance/leeway
Units: rad (Radian) Description: Current leeway
/vessels//navigation/leewayAngle
Units: rad (Radian) Description: Leeway Angle derived from the longitudinal and transverse speeds through the water
For sail boat performance calculations leeway derived by wind force is needed.
first one is for current (only) second could be for new transducers measuring longitudinal and transverse speeds. (If someone doesn't have this kind of transducer leeway is calculated by a formula)
Also taken into consideration, the technical bulletin of NMEA Org: https://www.nmea.org/Assets/20170303%20nautical%20leeway%20angle%20measurement%20sentence%20amendment.pdf
There is written for the ("new") LWY sentence (which exists in NMEA2000 too): This Nautical Leeway Angle is used primarily in the sailing segment of the maritime industry and may differ from oceanographic or scientific definitions of Leeway. *$--LWY,A,x.xhh**
"Performance" is calculated in reference to water, where current doesn't matter. So I believe, that the definition of Signal K PerformanceLeeway is wrong and should be changed.
For calculations of laylines, reaching a mark etc. a new Signal K definition could be declared which takes leeway AND current into account.