I didn't figure out how to arm my ships. I upgraded them in shipyard to max but when i try to battle i get the message that i don't have an escort ship (warship). I can't figure out how can i upgrade my ships to warships.
When you select a fleet it pops up in the middle right corner. You have 4 buttons that u can press, starting from left to right they are: ship list>cargo list>captain details>trade route. Click the ship list button and a submenu will appear under it showing you the ships part of the fleet/convoy. Click the ship that you equipped for war and just above the 4 buttons i mentioned earlier u will have a small button that looks like a cannon, click that and it becomes a warship ready for war. Hope it helped.
1) Select your convoy. It's the button on the left in the window of that displays your convoy information.
2) Click each of your warships then check the box that designates it an escort ship. You can only have 3 escorts max.
After you selected your escorts a blue bar should appear which will represent the number of sailors you have to man the cannons. When you feel good about the strength of your convoy just click to on a pirate to attack him and show no mercy.
FYI- Typically you will be fighting 3 ships of varying strength, I recommend quickly sinking two of the smaller ships (if there are any) then using grapeshot to kill off the crew of the remaining ship, once the crew is dead you can use regular shot to get their health low. The computer will automatically capture the ship when they are near death.
It's a good way to build up your fleet early in the game, repair costs will ensure you break even monetary wise. but you don't have to wait months to build ships and the captured ship will have at least one upgrade.