I'm looking into to getting a jump starter pack. My primary use would be carrying it on the boat in case of a dead battery. I was on a friends boat offshore last summer where we ran one of the batteries down and had to jump the engine to start it. luckily we had a jump pack on board, so it didn't turn out to be a major issue. I will need a pack powerful enough to start my Yamaha f300s. I would like to hear any recommendations from people who have had to at one time or another jump start an engine using one of these packs. I'm primarily looking at a noco gb70. So if anybody has used one I would love to hear your opinion.