I was wondering what the feeling is out there about a second battery. I don't sit and listen to a ton of tunes out on the water, however, on the odd day we might. How long until you would be worried about not getting a start.

I guess that's for when you add more crap (ie. lights, big amps and stuff???)  I've always been fine with one.  What I do keep around though is one of those portable battery chargers that you can just plug into the wall and jump start it with if you battery dies.  I think they're like 100 bucks at the hardware store.  It has saved me at least twice just from things being left on like the radio.

guys - for real go with an optima blue top marine battery:

http://europe.optimabatteries.com/publish/optima/europe/en/config/product_info/marine.html

i ride with my X-2 loaded with tower lights, speakers, amps, etc..  Not to mention we'll crank the tunes while filling the ballast / emptying the ballast.  I've had the same optima battery for 3 years now and it holds the charge. 

I was turned on to the battery when i lived in MN by Midwest Watersports. I talked it over with my dealer local here in CT at Inland Watersports - he now puts the optima blue top marine in all the mastercrafts / maristars he sends out the door.

i am adding a second battery this year.  i died twice on the water last year when tied up.  of coarse, i had the tower speakers and the loudest system, so i was the designated music guy.  after about an hour and a half, and a few beers later, the engine wouldn't start.  luckily, someone had a charger.  i learned my lesson and started carrying my own charger, but i figure i'd just install a second battery to eliminate portable "stuff"in the boat.