Ship battles are all about movement and the weight of your broad sides. Try not to charge the enemy if there is any chance of defeat. Arrange your fleet in a line across your enemies line of advance. By making the enemy run into your formation that allows your entire fleets broadside to fire on each ship as it gets in range.

Even if you are outgunned 6on1 fights are fast and the odds can quickly swing in your favor.

Chain shot is extremely good at slowing or disabling the enemy but there are a few limitations. When moving against the wind a ships sails are reefed and make poor targets. The chances of doing any significant damage with chain when the sails are not deployed is slight. Chain from the side is much less effective then a rake from the front or back. Chain shot on his broad side only has a chance of hitting one mast but a raking shot can hit 2 or 3 sets of sails and quickly demast the largest ship.

Fire: If your ship catches fire STOP FIRING THE GUNS.
Fire is the easiest damage to spot since you will get a flashing fire symbol on the unit card and the ship will visibly have fires on deck.

If you stop shooting the crew will take the time to put out the fires and the ship can return to the fight.

Sinking: If your ship is in danger of sinking stop all movement.
This is almost impossible to spot and you rarely have more than a few seconds to act. If you see the blue flash on the corner of the unit card immediately dropping anchor will save the ship. You can still fire but never move for any reason.

Maneuverability can be more important than fire power. I will take a 5th rate over a 4th rate any day the 5th rate can turn well inside of the 4th rate. 3rd rates have longer range guns and are faster than a 2nd rate. Being faster with longer guns or a better maneuverability means you get to pick when are where you fight. Two unanswered vollies can erase the difference in firepower then they are yours.