Sailing Speed Calculator
Calculations and graphs of sailing VMG vs TWA [github]
This repository is a Jupyter Notebook containing basic calculations of Velocity Made Good (VMG) for the most efficient way to sail to a given destination.
The notebook also includes wind polars for a Figaro 3 and generic 2015 Imoca (from qtVlm), as well as a generic wave polar (which shows percent of best performance achievable in a given sea-state).
While the polar data is boat-specific, I also calculate the required extra speed to make a decision to bear off viable. For example:
increasing TWA from 40º to 45º will increase the distance sailed by over 8%.
So in the above case, unless bearing off will increase boatspeed by > 8%, VMG will actually be worse, despite an increase in speed.