Trojan Boat Forum

I have a 1990 F32. I want to add a 750 W amplifier with my new stereo. I found suitable space in the STBD side salon, behind the sliding door, farthest forward behind the partition for the galley. It will mount to the 1/4" luan that seems to cover the aft vents. Question 1: is this an ok place to mount approximately 10# of marine grade electronics? Caveat: I believe I'll have to un-install the amp when I replace the air conditioner this fall for a reverse-cycle heating unit.

Question 2: it's 750 W and the tech brief calls for 4AWG 100A fuse. Obviously, I'm planning a 30A charger and 30A<100A. This boat doesn't have a deep cycle 900Amp AGM house battery, in fact it has 2 standard starting batteries. Since I'm a live-aboard, most of the time, the stereo will be played in the marina. Is this huge difference in draw a big deal? I mean, it's HIGHLY unlikely I'll use 1/10 of the amp capacity of the amplifier, so I would think never more than 10A, but it is requiring a 100A fuse. Also, where do I connect this? Should I add a fuse block under my service panel in the galley and install the fuse there or should I go back to the battery switch on the aft bulk head and install a new fuse there? Thoughts? Anyone else put a full car stereo in?

Thanks.

Hey bigralph!

On question 1, I'm really not too sure unless I was there with you. I don't have the same boat, so would rather have other F32 owners of similar models pick that one up.

On question 2, I'd say you'd be fine! Even though the charger puts out 30A, the amp wouldn't really be running off the charger as it would be drawing from the batteries. 100A is a lot of power, and honestly is just a safety barrier to prevent overheating and a fire if you had a short or were just absolutely blasting the music (i just cant see that much power being drawn from just that). Also, are you using all of the speaker outputs? If not, you'll definitely not pull 100A from the amp. Most batteries are almost 10 times the 100A fuse in terms of power supply capabilities, so they can definitely supply the juice... The real question is your gendset and/or your generator/alternator on the engine... How much does that supply?

The 4gauge wire should have the fuse block built in so you can connect it directly to the battery - that's how it should be done. There's a 18-20 gauge remote 12v wire from the deck that runs to the amp and tells it when to turn on and off (when your deck does). Don't worry about the amp staying on. If you connect the main power supply to a fuse block in the dash or elsewhere, you'll end up melting a smaller wire running from the main DC power bus. This would be kinda like having your garden hose feed a firehose to put out a fire - you're going to overload the smaller line.

Again, the 100A fuse is to prevent a fire in the event of an electrical emergency. You should be fine. I've been an Aircraft electrician for over a decade, and a lot of friends ask me to help the with their car/boat stereos. I've had vehicles that had a Pioneer 760 for 2x 12" subwoofers and then a Rockford Fosgate 1500 for the 6 speakers (a car I had years ago), and the 120A alternator lasted forever.

If anything, I'd be more concerned about what you mount the amp on due to the heat... I'd put spacers under it so there's an airflow underneath. There'll be a day when you want to crank some tunes, so you don't want to damage the surface under the amp, which I've seen done before.

Hope that helps! Happy boating!