Changing source of distance log on Raymarine plotter from paddle wheel to GPS

[Boathook]

When new i calibrated my log best as possible. Being able to see differences between 'water and GPS data helps when using back eddies and how well I'm actually manage to sail.
As Refueler mentions it also helps on arrival to various locations !

 

[dunedin]

For me .....

STW is good to tell me the ability of the sails and or engine as they are pushing through a body of moving water.

SOG is good to know when I can go prop up the bar !!

Yes I definitely monitor both speed through water and SOG to keep,an eye on currents etc - as often sail in waters with fast but complex tides.
But interesting reminder / lesson this year that need to trim sails to SOG and associated apparent wind, and not just speed through water. Sailing past Corryvreckan at times was doing 12-14knots SOG, and needing to sheet in tight for close reach - miss the best eddy and SOG dropped to 5-6 knots and wind swung astern to broad reach - sails out to be fast But don’t always have tide speeds and turbulence of Corry at springs