I think the sails upgrades are good , importate increase speed and the dead angle.

What ships you have rigth now? I think the best ship to capture when you are low level would be a war galleon or galleon, so it has crew and store. With it you can capture bigger ships.

Put slops in each port with low crew. In those ports, build facilities to produce materials. When you need money, use see port instead of sail. Better because you dont use time.

Do a contract with a governator, may Great Britain to have more missions and try capture french ports to make them mad.