Ok everyone, so I got a mid-level 2 channel amp (75 or 85w RMS) to power the Bazooka Bass MT8002BS Speakers on our Moomba Mobius Wakeboarding boat. We have a nice Kenwood headunit and we replaced all 6 speakers with Sony xplodes (my step-dad chose them, not me).

So I am going to attempt to drill the tower and fiberglass to run the speaker wire. My biggest question is, where I want to locate the amp is mounted on a separate rack I am going to build to keep it off the floor (and therefore dry), it is right beside the battery. Now the hull of the boat is fiberglass, so there is no where else to ground to unless I run a long wire to the engine block or somewhere (starter, etc).

Mounting the amp where I want to now will require about 12 inches of power wire and 12 inches of ground wire. I will be running an inline fuse on the power side. Will I be ok?

 

A-ok.

 

Thanks, I thought so.

 

The biggest reason we don't ground the amps directly to the battery for most installs is due to distance. The shorter the path of current flow, the less current loss in the loop. Since your amps are right next to the battery (and this would apply to a 2nd battery in a car install), there's no problem running the ground directly to the batt.

 

Thanks for the extra information, I was going to inquire why this was different, and that (distance) was the only thing I could think of.

 

When you really get into wiring, you'll find that wires are sold/rated (in part) by resistance per 100ft or 1000ft (or meter) - i.e. 55ohm coax has less internal wire resistance than 75ohm coax. Now, we use 75ohm coax for a reason (because RF has it's own set of rules).

This is why 1/0 is used instead of 4ga for higher power installs. There is less internal resistance (and can carry larger current flows because of that and heat dissipation due to surface area).