Quote Originally Posted by Ash
When I attack with stuff like Barques and Caravels one by one, they have a real high chance to sink against any ship.
If I attack with a stack, I always win unless the stack of the enemy is bigger.

The only thing is there's only one ship getting the valour while the others don't.
Then again you are guarenteed a sure win 9/10 times.
It is a bit of a dilemma: each fleet has a separate chance of catching the enemy fleet thus the more fleets you have, the smaller the chance that the enemy escapes. However, the more fleets you have, the smaller your individual fleets will be and the greater the chance that you will lose the sea battles. The best solution is to use fleets of about three ships against a single enemy ship. You will probably lose one or two ships, but that would have happened anyway and the trade revenue ought to compensate for that. Remember that a fleet is as fast as its slowest ships so don't put slow ships together with fast ones. The faster a fleet is, the greater the chance that they catch the enemy fleet.

AI ships get an unfair advantage against the human player: if you don't attack with overwhelming odds (say two or three to one), chances are that they will win. However, it seems that this is a sort of compensatory mechanism: if you are winning land battles, sea battles will turn out in the computer's favour. A number of players has tried to turn this the other way round by sending a unit of peasants on a suicide mission (thus losing a land battle) and then fighting the sea battles. They reported that this allowed them to defeat much larger fleets, something that is almost impossible otherwise. I must say I have never tried it myself, but perhaps this is a way to win sea battles.

BTW there is no such thing as ship valour, only command skill of the admiral.