Naval tactics!

[Marquis of Roland]

I generally try not to cut the enemy's line. While this was effective in real life, ships in the game light up like a matchbox whenever they touch fire (even more so than real life ), and if you're concentrating fire on parts of their line, enemy ships inevitably will catch fire. Also, the risk of the AI just plowing his ship right into yours while you're cutting his line will create a huge logjam of ships and without extensive micromanagement your line of battle is screwed.

I always try to gain the weather gage (being upwind) before I go in, then go in at such an angle that, when the AI turns its line to face me, the lead ship sail directly into the wind. This causes their lead ship to lose control and speed, and usually the ships behind will run into it. I then sail my line of battle in a tight semi-circular zig zag pattern around the AI's mass of ships in the middle and just shoot them to pieces (while they're bunched up like that they are very vulnerable to ship explosions).