Enough with the math! Vectors, smectors!
Put the coordinates of Point B in the GPS, note the bearing thereto, use that heading to start and after a few minutes note the COG on the GPS. Adjust your heading so that the COG equals the bearing to Point B.
And dontí tell me about losing power and GPS failure and all that. If that happens youíre just SOL.
PS -- it helps to plot a line from A to B on a real chart so you can be sure there are no hard things lurking along the rhumb line.
But seriously, in small boats itís hard enough to steer within 10 degrees of the desired heading. So pre-planning a few degrees of windage is an interesting exercise, but it shouldnít replace knowing where you are and where youíre going in real time. Thatís what makes GPS so great!