Sounds like a great idea! Weather has always been a system in UO that never really lived up to its potential.
This would probably be as simple as creating a wind direction enum and having the Weather system determine which direction its blowing based on some random equation for each region, the same as it randomly determines the weather patterns. Then in your boat code you'd check to see if the boat is moving the same direction, and gain a speed bump, or conversely moving in the exact opposite direction it would suffer a speed debuff.