Just bought these for my Towtruck’s, they start everything. We are have daily problems with new high accessorized cars not jumping. These things get it done.
I'm a NOCO owner too just like @Jefftowz. I opted for the GB40 Boost+ to keep in the boat because the 1000 amp jump-start current was more than enough for my Merc 5.0. Crutchfield threw in a carrying case for it too so everything fits nice and neat in the bilge toolbox.
I've never had to use it on my whip but I've jumped plenty of other boats with it. Works great every time and I can get two jumps before having to charge it back up.
I have dual batterys and dual perkos so I can choose which battery the amps run off of. The NOCO provides a great peace of mind if I drain one and flip the AMP perko over to the other battery way out in the back part of the lake.
I'll third the NOCO. I have a GB150, mostly because its also big enough to start my truck (7.3l) if I need it to. Haven't needed it for the truck, but did have to use it a few weeks ago on the boat since I found strangeness in the wiring that left me with a no crank on one motor. The NOCO worked great!
If anyone was considering the NOCO's, they are on Prime deal today (Amazon), for the next 11 hours. I was on the fence, but the sale got me. The GB150 can be had for $192, so I went for it. Looks like all the models are on sale.