Alternator ?
 

Sounds like I need a alternator for my boat what do you guys think ?
When I start my boat up am only getting about 8-9 volt's on the gauge at idle and going out of the marina but when I get out on the lake/river and get the boat up on plane the gauge say's 12.5 volts.
so to me sounds like the alt. is bad but are there any ground wires or anything I should check 1st befor buying a alt and do you guys have any good source's for buying one that wont cost me a arm and a leg?
What is the diffrents between a car alt and a boat one ?

thanks for any ideas

Pull it and have it rebuilt. Most metro areas have shops that can help you out. Should run $50-$80.

Boat alternators are different from a car in that they have spark arrestors on the back due to the explosive environment they're mounted in. DON'T put in one not rated for a boat.

Thanks for the info !!! I found a guy this morn just a few miles from me that will rebuild it.
I did see the spark arrestor on the back makes sence Thanks again.