Assuming you have a mercruiser its the engine gaurdian system. The alarm you hear when you start up is they system telling you it works. Your manual should have the decoder ring of what the beeps mean when they come on. If the engine is running and you start to get beeps then its warning you that something is wrong.
The Engine Guardian System monitors the critical sensors on the engine for any early indications of problems. The system will respond to a problem by emitting a continuous beep and/or reducing engine power in order to provide engine protection. If Guardian System has been activated, reduce throttle speed. The horn will turn off when throttle speed is within the allowable limit. Consult an authorized Mercury MerCruiser dealer for assistance.
May not be the best link to what the beeps are but its what I could find with a quick google search
My Johnson outboard does the same thing too, I think it is just doing a system check like when you go to start a car and all the trouble lights come on, then go out when they have been tested good.
At least on an old boat like mine it means there is no oil pressure, which would be normal until you start cranking the engine. If it still is sounding when the engine is running you know you have low or no oil pressure and you should shutdown the motor and check things out.
My Johnson outboard does the same thing too, I think it is just doing a system check like when you go to start a car and all the trouble lights come on, then go out when they have been tested good.
My grandfather told me when I was young those were "terrible" lights. He said when they come it it usully means that something terrible was wrong and it would be terribly expensive to fix. I guess even more so for a boat! Thanks for the trip down memory lane...lol
I was going to say both the boats in my signature.... But apparently I don't have one when posting from my phone. So let's try this again.... I'm guessing you have a carburetor not fuel injection. If so I suspect its like I said.
