By Matt Claiborne
If you have a key that works, take a trip to your local hardware store and have them cut a copy of it ASAP.
If you contact that manufacturer and give them the exact make, model, and serial number, they may be able to supply a working replacement boat key.
Your next step would be to call around to local locksmiths and see if any of them offer boat key services.
If you were lucky enough to lose your keys while the door was unlocked and can get inside, you can probably easily remove the entire lock assembly.