Is there any way to accelerate the game speed in Windward? Sometimes it takes a very long time to sail from one end of the map to another.

There is two command to change the ships behavior with the wind, but there is no ption to alter the game's base speed.

minSpeed ​​← (0.0 to 1.0) value representing how quickly shi ps can travel when sailing into the wind.
maxSpeed​​ ← (0.0 to 1.0) how quickly ships can travel  when sailing with the wind.

According to the manual, you can sacrifice XP and loot gain by setting the challenge level to 50% to get a similar effect. The higher the challenge level, the more the wind matters.

Yes. The challenge level works the same as the min/maxSpeed server option. At 50% challenge the minSpeed is 1, while at 200% challenge it is 0.35 if I remember right. This means, against the wind at 200% difficulty you lose 2/3 of your speed. With 50% difficulty the wind not affect your movement. Between the two the minSpeed scale linearly. Flying ships more or less completelly ignore this.

So, once you get a flier, grinding gets even easier than it already is. And if the XP bonus updates dynamically with the other variables, a nasty grinding cheat can form by taking advantage of them: just set challenge as high as the engine will take it, set the skill multipliers (other than movement speed) as low as possible for the faction (normally 80%, but can be set lower with commands, i assume), then use a flier to do quest runs. Possibly getting max capped XP for every quest.

I never tried exceeding the given limits, maybe it will work. Then yes, everything will worth a lot if 400% or more possible. Anyway maybe there is a small punishment for flying ships but generally they have the same speed no matter the wind direction.