needs improving
upgrade ideas were nice, but problem is that even if yu have the best boat, if the opponent is one new upgraded boat ahead, he always wins, and there's no way to do anything about it....
i think you should add the following:
- ability to SELL upgrades again, so that you can buy a better boat
- more money from shooting boats (didn't really help me...)
- power-ups on the water
- instead of having to start over, save, or at least give possibility to go BACK to the SHOP after a failed level, so that we can change something about our config (for ex. if I bought an extra cannon, but I need more speed, I'd sell the cannon, and buy more oarsmen instead)