Say you had a standard small sailboat with a sail and a reef the keeps the boat going straight. If you wanted to go North and the wind was blowing East, what would be the most optimum angle of the sail from the vertical, or horizontal, that would provide the most positive vector component forward.
which direction is the current flowing?
Just kidding. The problem with your question is, that there may be one answer on paper (probably 45 deg to the wind, or something similar) but sailing is more of an art than a science when it comes to balancing all of the forces involved. That is why skippers sail the Cup, rather than autopilots.
There’s no cut-and-dried answer. You don’t specify a wind speed, and there’s no such thing as a steady wind. Generally, though, you’re on a beam reach (the wind 90 degrees from your path,) which is pretty simple to sail. Just point the boat toward north, and trim the sails in until you’re going as fast as you can without heeling over uncomfortably. As the wind varies, you’ll have to adjust the sail trim.
I should have been more clear in my question. Assume a constant East wind and no water current. This is more of a physics questions than a sailing question.
What’s the wind speed? Where’s the waterline on your hull? What’s the shape of your keel? Of what materials is your boat made? How massive is it? What is the shape and size of your sail? Even given all of that information, I’d still be unable to answer your question (fluid dynamics is notoriously tricky), but I’m certain that it’s unanswerable without that information.