New wiring on old boat

[ex0r]

Anyone here know if a special battery is needed on boats? I have a spare 12v battery that was in my car before we junked the car out that I was going to use in the boat, and it fits nicely in one of the plastic battery boxes, but wasn't sure if I could use it for marine purpose or not.

I had to rip out all the old wiring for the boat, and am rewiring it, so I am going to wire the battery into a fuse box and than each device to it's own special fuse, one for the lights, one for the radio, and one for the motor/horn. I've done wiring in cars before, but not exactly sure if it has the same type of wiring for a boat. Here is a simple schematic to see if I am on the right track.

Hopefully that's readable. Basically, the battery has it's own ground which attaches to the boat somewhere via a metal plate. The + of the battery goes directly into the fuse box, in which it's distributed to the other power sources, and the negative of the other sources are all tied together to a ground (either the same one as the battery, or a different one).

Let me know if that looks right or not.

 

[sea1tech101]

Re: New wiring on old boat

You probably would want to use a marine battery because of it's deep cycle. A car battery is meant to have 13 volts or so run to it while engine is running (which comes from alternator). Pretty sure older boat motor don't put out as much as alternator would. As for the wiring looks you going to have it wired to the ignition first. If so, then all electronics will work off key switch. Depending on what kind of boat that is(pleasure boat,bass boat,etc), this my not be to your benefit. You should put all your electronics on a separate switch. Your grounding looks little off according to the picture. Ignition system needs it's ground. Maybe someone else when comment on top of what I said.

 

[Silvertip]

Re: New wiring on old boat

Age of the outboard doesn't matter as far as the charging system is concerned. 12.6 volts is 12.6 volts whether it comes from an old motor or a new one. What is important is the CURRENT output. Older outboards tended to have 6 amp (or thereabouts) alternators. Newer models run anywhere from 15 to 60 amps. The chassis of the boat is NOT a ground point like a car. Many fuse panels have a ground buss built into them so the accessories get grounded to it. A largeer gauge ground wire runs from the buss to the negative terminal of the battery. Yes == you can use the car battery in your boat.

 

[NYBo]

Re: New wiring on old boat

Yes, you can use a car battery in a boat. However, do NOT run you fuse panel through the ignition switch! Run dedicated 10 or 8 gauge wires for the fuse block and negative buss bar, with 30 amp fuse or circuit breaker on the positive lead as close to the battery as possible.

I can't believe you missed that, Silvertip!

 

[ex0r]

Re: New wiring on old boat

Thanks for all the info, it was useful.

As for the ignition system being on there, I planned on using a system similar to a car, with three steps. 1 for off, 2 for accessory (So I can keep the radio/lights on with the boat and motor off), and than run so that the motor will start. I wanted to do it that way, so that one of the switches can't accidentally be turned 'on' without the key in and run the battery dead.

So you guys are suggesting to hook the ignition switch up on the OTHER side of the circuit, and connect it only to the motor to turn the motor on/off? Is that how it typically works?

As for the ground, I was going off of what the current wiring system uses. The antenna that I took off had a metal plate on the inside and water side of the boat, and the wire hooked to it on the inside.

The current fuse buss is currently still there, I will take it out and check to see if it has it's own negative post on it, which I am sure it probably does. I am relocating the buss anyways when I rewire it, so it has to come out.

As for the wiring and all that, yes. I picked up a roll of wire that has 6 different colors. Red, blue, black, green, white and yellow. I also have a label maker that I am going to use to label each wire individually, and at any junction so that later on I can easily identify which wire goes to what device. As for covering it up, I plan on using the plastic wire loom with electrical tape wrapped all around it, and to secure it to the boat, I am going to use those adhesive cable tie holders and cable ties all around to make it nice and secure. I went to the local electronics store yesterday and picked up a huge selection of male and female two prong connectors so I can connect everything up and also picked up some new solder. I think it'll be easier if I measure the wire individually where it needs to go, solder all the terminals and etc up, than place it all in together.

Thanks alot for the info guys, it's been much helpful, and I will adjust my diagram later today and post it back up again to see if it looks okay!

 

[j_martin]

Re: New wiring on old boat

A few clarifications.

Most boats have some circuits that run off the ignition switch accessory terminal, usually just instruments and the only fuse is the ignition master fuse.

Most other accessory equipment, radios, depth finders, even lights and bilge pumps are run off a separate master power switch, followed by a distribution panel where the individual circuits are fused.

Battery ground is to the engine block. Do not use metal boat parts for ground return for current. You will find small ground faults if you do, as corroded holes in the boat.

hope it helps
John

 

[ex0r]

Re: New wiring on old boat

Thanks for all the info guys, I have everything electrical I need so i can start wiring it up, but I had a few questions regarding some other electrical stuff.

Can I buy any instrument cluster for a boat and use it on any boat, or are there certain ones that need to be used with certain motors? I don't have the original gauges and stuff, they were destroyed. I did find some (both as individual round gauges, and as clusters like on vehicles) from cabelas.com, just wondering if I can get those and wire them up to how they should be wired (To the motor for rpms, speed, and to the fuel pump sender for the fuel level).

I also was wondering about steering wheels. The original one was broken, so I had to cut off, so the shaft and everything is missing. Can I buy a universal steering wheel assembly with the shaft and all and use that? (It was a cable steering system, you can see the pulleys all through the boat where the cables attached to it).

 

[Silvertip]

Re: New wiring on old boat

Instruments are quite generic. The only engine specific types are trim gauge and in some cases the tach may need to handle a alternator with other than 10 or 12 poles. Speedometers, gas gauge and temp gauges are not engine-specific. The only other issue is whether you have an outboard or an I/O. I/O gauge sets usually include oil pressure and water temp gauges. Outboard sets typically have speedo, tach, fuel, and perhaps trim. You will need senders for the fuel gauge and trim gauge. The trim sender is specific to the engine.