Anyone ever have to use this..

KYSEAN

http://www.mpowertech.com/jump-it-car-jumper-cables/  Could be a little piece of mind.

Black_Diamond

I know people who carry similar things, esp on smaller boats. Handy devices.

TikiHut2

I carry a jumpstart pack that's a bit larger and fully capable to jump the engine in a pinch or power the raft air pump. All for about $40 at Harbor Freight.

Dream_Inn

I too used to have a jumpstart pack. Used it to also lower the hatch when I disconnected batteries on my prior boat. But, it got wet after a high tide in my dock box, & with my current boat I don't think I'd have a need anymore. Great though for a lot of things. I had used it with an inverter at home to run my fire place insert fan when I lost power.

Hamdog

I have a jumper box and use it a lot. Most use is to blow up rafts/floats but have loaned it a few times so a dockmate can jump his boat. Peace of mind in case mine won't start one day.

gslpro

I actually had someone swim over to us last year asking if we had jumper cables.  We did not.  Never thought of them on a boat.  I radioed for marine Patrol to help them, and decided to add a jumper pack to the boat this year, just in case.  Most of my emergency items have never been used on me, but frequently for others.  (Thankfully)