305 belt problems

[Fabrimacator21]

Ok. Everytime I take my boat out the v-belt flips over at full throttle. Belt is new and alternator seems to be plenty tight. What could this be? Is it just not enough tension or do I have a bad alternator or water pump?

 

[4X4HIGH]

You need to first check for proper pulley alignment and then make sure it is the proper width belt.