General tips:

Try to not repair ur ship in first 3-4 battles (depends on RNG)
Upgrades don't really matter but go rather defensive upgrades later levels the enemy goes to very far distance so might as well try to go long range battles upgrade (mortars and cannons that do damage from long range)

Other option is need Harpoons to get the other ship hooked and then you can go ramming.



Here is how i done it: