When i turn the key i can hear it trying to start but the engine never actually turns over. Also i took the battery out and took it to a shop who tested the charge on it and said it was fine. I also checked on the fuses, and just checked the circuit breaker and everything seems fine there. I remember someone telling me that i might need to change the sparks plugs after a while, as they have never been changed and the boat has over 250hours on it. Could this be the problem? If so i don't know where they are located?