I am planning to upgrade the stereo in my 2003 Cobalt 226. I have already ordered a 10" 100W Bazooka Powered Sub (MBTA 10100) which I will install first.

I am also considering installing a 4 channel amp to power four of the six 6 1/2" speakers in the cockpit. I don't plan on doing the amp right away but want to put the necessary infrastructure in to make the amp install as easy as possible when I do it.

A few questions:

* How do I know what gauge wire to use for the power?
* Where do I hook up the ground for the new components? What gauge wire do I use for this?
* Do I need to run the power or any other wires through conduit or ducting?
* Any other suggestions on how to make this install safe and optimally functional?

Thanks in advance for your help!

For wiring, I would go with 2 or 4 ga for primary and ground. Run each from the battery (positive fused closed to the battery) to distribution blocks near the stereo. On the positive side use a fused distribtution block which is water proof. Now you have places to wire in the amp in the future.

I don't have a lot of time right now, as I am off to work, so I'll be brief.

I am glad you have safety in mind. For that, I always refer to the USCG publication "Boatbuilder's Handbook". I am sure some of the regulars hear me refer to this ad nauseum, however, I think it is a very good resource.

Electrical Section of the USCG Boatbuilder's Handbook

In fact, anyone contemplating any electrical wiring in their boat should be familiar with this publication. Although its audience is intended to be boat manufacturers, it is not that difficult to read if you posess the skills to do the wiring in the first place.

I can elaborate further on wire selection later if you wish, but first, familiarize yourself with the above publication. It isn't that large, and you can read the entire thing in maybe an hour.

Try this site for a wealth of information. You need to look around a bit to find what specifics you are looking for, but they ARE there somewhere. A great resource.

http://www.the12volt.com/

Without trying to hijack this thread, can someone also comment on wiring an amp to the battery switch? I have 2 batteries and obviously want to control which battery its being powered off of. Any reason I can't wire it accordingly to the "feed" terminal? I'd then ground the amps to the engine block.

Edit- I did some research and it seems I need to find out how many amps my particular switch is rated for. Looks like the amps will draw no more than 80 amps.

Hey guys. Thanks for the information. I plan to review it tonight and circle back with any questions I still have.

A couple more questions:

I can probably mount the sub/amp in two different spots. The first being below the aft bench seat that contains the dual battery switch and is very close to the batteries. I guess the advantage of this would be less power/ground cable to run but longer RCA/speaker wires to the head unit.

The second option is under the Port lounger in the bow. This cubby opens up directly to where the head unit wires come out and is spacious enough to mount the amp on the side of the cubby and the sub in the bottom of the cubby. Of course, I would have to run some long power and ground wires to get all the way back to the battery but it would mean much shorter RCA cables.

Any suggestions on which of the options would be best?

Thanks again.

Having had some experience in this area, my initial thought would be to run as short of power and ground as you can while keeping the amps in a safe and dry location. When I installed my new amp I ran all new power and ground from the battery to the helm and its not cheap! However, I would be mindful of any additional electrical components in or near the engine compartment. Follow Al's advice. Don't forget you'll not only have to run RCA's back to the amps for input, you'll have to run all new speaker wire from the amps.

So, having said that. It might be easier to run just the longer power and ground. Boy, my stream of conciousness was a lot of help wasn't it?

Cincy - that's exactly what I'm thinking.

I would much rather just run power and ground even though it might be more expensive. As long as it is going to be safe to run potentially 20' of ground and 20' of power. Can I run dist blocks for the power and the ground so I can just have singe runs for each?

It will just make for a cleaner installation because I really want the amp/sub up by the passenger compartment.

I ran my power and groud for my amps to the compartment in front of the helm 3 years ago, and I want to say it was about $125 just for those two cables. However, like Cincy said once its away from the engine heat and moisture.

I am not sure if this is being contemplated but you should not place the amp in the engine compartment as it is not likely ignition rated. According to the USCG, all components must be ignition rated in the engine compartment.

The real issue I see having is wiring distance, as you have to use larger wire as you increase distance to keep the voltage drop from being excessive.

Rather than write all this stuff agin, here is an article I wrote a couple of years ago about high-power wiring for a radar installation in a boat. Even though it is for a radar, it is applicable for stereo use.

http://members.toast.net/boatguy/cproj5.htm

An as a sub article, here is one on just wire selection for high-power use.

http://members.toast.net/boatguy/highpower.htm

You should read the first article, even though it deals with radar because it sets up the frame of reference for the second article.

One caveat about the article. I made mention that many car stereo guys use a large capacitor to help alleviate the voltage drop situation. However, I would caution against its use in a boat. The reason being that if you disconnect and reconnect the battery, and if there is sufficient current stored in the capacitor, it could result in a spark. Never a good idea in a boat's engine compartment.

One last observation. If you wire directly to the battery, the USCG requires a fuse or circuit breaker within 7" of the battery. This is best served by a battery-terminal fuse, of which there are marine grade types.

Hope this helps.

Al,
Thanks for the links - they are very informative.

I tried using the calculations provided but I'm not sure if I am using the correct variables for Amperage. The subwoofer is a Bazooka MBTA 10100 which comes with a 75 amp fuse. The power wire that came with this sub is very small gauge and I'm not sure if I could even get the supplied power cord around a recommended 8 gauge wire because it is so small. The amplifier I am going to use is a Sony XM-604M which has two 25 amp fuses.

Is it best practice to derive the amperage from the fuses attached to the equipment? Or is there another way to get this number?

Okay - I'm getting old and I can't see as well. The fuse reads 7.5 not 75!!! Making much more sense now...

Amplifier = 25 x 2 = 50 amps
Subwoofer = 7.5 amps
TOTAL CURRENT = 57.5 Amps

Length = 26 Feet
CM = 37,360 (4 gauge wire)

E = (K X I x L) / CM
E = (10.75 X 57.5 X 26) / 37,360 = 0.430173

This represents a 3.6% drop in voltage on a 12V system. If I bump up to 2 gauge, I can get E = 0.257346 or 2.14% voltage drop. You think the 2 Ga is worth the extra bit voltage conservation?

Run cost analyst, see what the net cost difference would be.

Remember that in a stereo system, you are not going to draw 50+ amps constantly, but only during musical peaks - and then only if its cranked way up. Most of the time, you'll be demanding much less current from the battery.

For that reason, I believe that the 4AWG wire, with the 3.6% voltage drop, is going to be sufficient for all but the small time you will be demanding maximum current from the system (if you even reach that point).