A game with potential for great scale and depth of gameplay. It's got exploration, combat, trading and quests, possibly RPG characters too ;)
Seems like you've already got a good bit of feedback so I'll just add my 2 cents:
- Ahoy button is a great idea :)
- The instruction WASD for movement is misleading, perhaps W = forward, A = turn left, D = turn right ? S key doesn't seem to do anything
- Music is great but you could really do with some audio FX for battle (cannon fire, hit damage) and maybe for when docked (ambient town sounds)?
- Little touches like cannon smoke when firing and explosion debris when ships are hit, wakes left by the ships as they move, animated waves.. would be nice. You could do with some artists/designers ^^;
- As travel between islands could be long and uneventful, maybe add random events or text quips by characters to add flavor and reduce boredom?
- Ships go from port to port but they don't dock. It'll probably enhance immersion if they wait a while at port (for trading, repairs, restock...etc) before setting off elsewhere.
- Ships spawn in the middle of the sea. OK for surprise random enemy encounters due to fog of war, but maybe you could spawn normal ships just outside the viewport so they don't magically appear?
Anyways, a very promising basis to build into a great game. Keep at it!