daft wrote:
Standard wind drag causes leeway...
But some contact with boat designers (book and forum) made me aware of another contributor to leeway: a shallow surface water current driven by the wind if it has enough speed, fetch, and duration.
Surface water current? If the wind has sufficient speed, fetch and duration, you will get waves/chop. That will definitely slow you in a little light boat and provide opportunity for more leeway. Your other scenario when in protected waters has also eliminated fetch so you "shoot upwind".
Seriously, I don't think you need concern yourself about a surface water current causing leeway.
If it helps you, though, by all means, invent more reasons why you can't go to weather.