How do I correctly use a portable power pack for jumping battery?

[Scarab]

Hi-may seem a stupid question, but I carry a portable power pack for emergency starting if main battery goes down-what is the correct way to join device up?
Bearing in mind-the unit instructions says DON'T connect earth lead to battery, but connect to metal part of chassis- fine on a car, but what do you do on a boat?

[Murray]

Interesting question, guess I’ve been doing it wrong. If the instructions don’t want you to use the negative post then you would have to use the block or somewhere on the lower unit. Do the instructions say why not to use the negative terminal?

[Harper]

Reason for not using negative terminal, and this advice is given for jumping batteries from ANY source, is to prevent spark near the dead battery, which could cause an explosion if the battery is outgassing. The positive is always hooked first, then the ground, away from the battery. That said, I've never seen nor heard of any such explosions. And, you are likely not going to find anywhere to hook up the negative on your power pack except the negative battery terminal. If it were me, I wouldn't worry about it. The jumper cable manufacturers and power pack manufacturers have to cover their butts against any liability.

[Murray]

The block wouldn’t work? Specifically the lifting hook.

[Harper]

Sure. It should. My bad. I'm thinking about my boat.....the batteries are under the console, 10+ feet from the motor.

[Moonlighter]

On pretty well every outboard powered boat, its going to be “challenging” to connect the negative to a negative terminal on the engine. Especially at sea.

[Matt LeJeune]

I own and have used the Noco GB40 jump pack which can be hooked to the battery terminals, it claims to be "spark proof" I don't know how that is possible. when I connect it I connect the two terminals to the battery then it has a waterproof disconnect plug that I connect to the jumper, then turn it on. It's also rated IP65 water resistant. It is designed for 12v lead acid only. I own another the Halo Bolt that I keep in my truck for misc. charging and the security of a jump start, but the Noco had better marine environment features.