Join Date: Nov 2007
Location: SF Bay area
Thanked 7 Times in 6 Posts
Rep Power: 10
I'm casting my vote in favor of B.
Boat A has no choice but to drift with the current. If she somehow manages to alter course and make headway in any direction at all, her apparent wind will always be dead ahead, and so she can never sail.
Boat B can alter course to close-hauled. Let's pretend the finish line is infinite long and forget about Boat B's tacks. Boat B will now make, say, 5 knots over water on her heading 45 degrees away from the set of the current, which is 3.5 knots made good in addition to the current, or 13.5 knots made good toward the finish line. She will experience some leeway, but its component in the upstream direction should be less than her additional 3.5 knots. This beat's A's 10 knots, so B wins.
I don't see how this situation is substantially different from two boats in a sea with zero current, and one (B) has ten knots of wind blowing from the finish line, whereas the other (A) has no wind. There may be some wind-against-tide action affecting B, making her tacks take slightly longer (that's one of the reasons I'm imagining an infinite finish line), but as long as she can average any speed at all upwind, she wins.
s/v Laelia - 1978 Pearson 365 ketch