Kevin,
I am establishing a separate 24 volt battery bank in the bow of my 35 foot sailing boat for a bow thruster.
When I do the boat wiring, do I need to run a ground wire from my engine block to this bank? How large does the wire have to be?
Thanks,
Bill
Hi Bill,
In my opinion, all grounds should be connected together on a boat.
As for the size of the boat wiring, I would recommend no smaller than the largest wire connected to your existing battery bank.
Hope this helps,
Kevin
Kevin,
Ok, so I just recently purchased a 1966 18ft Caravelle trihull boat.
Are there any boat wiring diagrams or anything like that for me to use for the rebuild?
Jake
Hi Jake,
Probably not. You may be able to use our standard boat wiring color table combined with a meter to decipher the wires. Most likely you will end up pulling new wires for circuits that just don’t work anymore.
Our partners at EzAcDc have everything from bulk boat wire to snap together boat wiring systems that would work great in your boat.
Good luck,
Kevin
Hi Kevin,
My aluminum boat wiring has the negative returns and negative side of the battery all tied to the hull.
I would like to isolate the negative return and run all negative returns to the battery with the hull isolated.
My question is: What do I ground the aluminum fuel tank to? It is connected to the hull.
Thanks,
Scott
Hi Scott,
Grounding to an aluminum hull is un-avoidable. Some components just end up being connected. You are actually at risk of even greater galvanic corrosion if the hull is not tied to the negative side of your system.
I would recommending running grounds for all components and not using the hull as a conductor. To comply with the USCG requirements, the metal components on your fuel tank (the tank itself) need to be connected to the boat’s DC negative ground also.
Hope this helps,
Kevin
Hi expert people:
Last year, I purchased one of the fully-wired switch panels from EzAcDc, but I still haven’t gotten around to installing it and find that I have some questions:
- I have two wires from the green and red bow light and two wires from the white stern light. Are these the navigation lights? And how do these four wires attach to the switch panel?
- I have two halogen head lamps with two wires from each. Where do these wires attach?
- I have two sealed beam cabin lights with two wires from each. Where do these wires attach?
- I have an on/off bilge pump with two wires. Where do these two wires attach?
- I have an air horn with two male blades on the pump and a little black box with four male blades and a hieroglyphic on the side with the numbers 85,87,86 and 30 & 12V 30A–no wires. How do these attach to my horn switch at the switch panel?
- I would like to add a stereo to the panel since there are two existing speakers mounted in the cab. How and where do I hook this up?
- The boat has an existing ground bar which I have wired to the battery switch and a fuse bar which I have wired to the battery switch positive pole.
- I have 10 AWG wires from the two batteries to the battery switch and 10 AWG wires from the battery switch which attach to the negative. bar and the fuse bar. The exception is the two engine wires which appear to be 4 AWG. Will this work OK?
- There does not appear to be any empty blades at any of the switches so I don’t know how to wire the switches to the wires which come from the lights, horn, bilge and other yet to be purchased accessories etc.
- What is the purpose of the voltmeter?
- I have attempted to remove a wire from the back of one of the switches but it wont budge. Is this a malfunction or are these wires not meant to be removed?
I have read all the posts on your website as well as numerous other posts on many other boat wiring websites but still want to make sure that I am doing this correctly.
These must be boring, inane questions to someone like yourself who obviously knows electricity and components, but I need help.
Thanks,
Ken
Hi Ken,
The easiest way to connect your boat’s components to your new panel is by using the 6″ long adaptor harness that you should have received from our partners at Ez. It has a large white 12 position plug that connects directly to your panel and the blue butt connectors connect to your boat’s components.
The adaptor wires follow standard boat wiring colors. That is…
Here is what you will want to do:
Having said all that, a simpler solution to all of this would be to purchase one of the EzAcDc Snap Together boat wiring harness.
Any of these harnesses contain all of the wires required to connect your red/green/white navigation lights, your head light/docking lights, your courtesy lights, and your bilge pump. There is a 12 position connector on the harness that will plug directly into your panel. They also include the power wire (with circuit protection) and ground wire required by your panel.
Your stereo can connect to one of the 3 position accessory plugs on the panel. Use the black for ground and the red for your positive.
Here is a schematic that shows how I recommend wiring a battery switch. Note the battery cable sizes. If your engine battery cables are connected to your ground bus and battery switch, your 10 AWG wire will overheat when you try to start your engine.
When you push the voltage button, the voltmeter will show you the current voltage of your battery and how much “fun time” you have left until your battery is dead.
If you use the adaptor, there is no need to remove wires from the back of the switches. In the event that you would like to remove a wire from one of the switches, I recommend using a flat screw driver. All of the switch terminals are .250 faston connectors. The back of the switch has .250 tabs on the back similar to the ones on the horn relay.
I hope that this is helpful.
Please let me know if you have any questions,
Kevin
Kevin,
I would like to connect the compass back light wiring (two wire lead) to either the navigation light circuit or the gauge lighting circuit. Both have separate switches.
The boat is a 1998 Bayliner 2452, which has had a few amateur boat wiring projects.Any help would be greatly appreciated.
Thanks,
John
Hi John,
The simplest way to connect your compass light is to wire it to your closest instrument.
Happy wiring,
Kevin
Kevin,
Thank you for the prompt reply. Sounds like a pretty straight forward connection.
John
Kevin:
I recently bought a Rawson 30’ sloop that was originally built in 1964. As the boat wiring is questionable, I plan to go through the entire boat and rewire all the circuits.
My biggest concerns are the navigation lights – five lights, L.E.D., each pulling less than 1 amp – with a total round trip of 200’ feet and another circuit carrying interior lighting – four lamps, L.E.D., each pulling less than 1 amp – with a round trip length of 100’.
Using a chart from a book by Don Casey called Sailboat Electrics Simplified, I’ve come up with a requirement of six gauge wire for the navigation light circuit and 8 gauge for the interior light circuit.
I thought this sizing was a little questionable (heavy wire for such light loads), so I asked an electrician at the shipyard where I work and he assured me that 12 gauge for the navigation lights and 10 gauge for the interior lights would be more than sufficient.
The reason I’m calculating such a long trip for navigation lights is that I’d thought a navigation light at the top of the mast was required. Is one required for a 30’ foot sailboat whether sailing or motoring?
Thanks for your time and information, Kevin.
Sincerely,
Dave
Hi Dave,
A while back I created a boat wiring size calculator that is considerably easier to use than charts is a book. Here is a link.
If you enter the amperage of your light in cell C8 and the total length of your run in cell D8, the E8 will give you your wire size. To comply with ABYC, you will need to keep cell B8 at 3%.
As for your question about the rules for navigation lights, here is a link to the USCG requirements.
Hope this helps,
Kevin
Kevin,
I love your articles about marine electrical. I’ve been reading loads of them and have learned a lot Thank you.
There is still one boat wiring thing that I can’t find an answer for.
I was in a friend’s boat and he said he has been having some issues with the DC circuits on his boat wiring, specifically, the fact that he has trouble running more than a few instruments without blowing a breaker.
I looked at his DC distribution panel and was a bit confused when I noticed that as you turn OFF breakers, the amperage needle goes down? I always thought your meter showed total output and as you turned ON breakers acquiring a load the needle would drop. And turning things OFF the needle would return to show full output?
Am I missing something here?
Michael
Hi Michael,
The amp-meter is measuring total current being consumed. The more items on, the more current – fewer items means less current.
It is easier to explain with water.
When all of the faucets are turned off in my house, no water is flowing, and the city water meter is not turning. This would be similar to all devices turned off on the boat…no current on the amp-meter. When my kids flush every toilet, leave on every faucet, and turn on the sprinkler system at the same time, there is a ton of water flowing (high current on the amp-meter) and I “pop a breaker”.
Hope this helps,
Kevin
Kevin,
I am fixing my marine electrical system and after a lot of reading and forum exchanges I came up with this boat wiring diagram.
The problem is, I can’t figure out the size of the fuses on the wires from the two banks to ACR and the boat battery switch. Currently there are no fuses at all, and the previous owners did not have any problems for many years. From the common on the switch power is used for navigation lights, cabin lights, anchor lights and stereo system. Nothing else.
Is my diagram working? What size should the fuses be?
Your suggestions would be greatly appreciated.
Best,
Horia
Hi Horia,
All circuit protection should be as close as possible to the source of power.
With the marine electrical setup in your diagram, if you put the battery switch in the both position, the fuses in the leads between the battery switch and the battery with blow when you start the engine.
I would remove both of these fuses and use a minimum of 2 AWG between the boat batteries and the switch. I would use a minimum of 2 AWG for the ground wires between the batteries and the boat ground bus. If the ground bus is petite, I would run my common ground wire from battery negative to battery negative or increase the size of the bus.
There should be circuit protection in the lead that runs from the common on your battery switch to your distribution buses. This should be sized at either the load requirements of your distribution system or the maximum current carrying capacity of the components leading up to the load center. For example, if you panel board requires 100 amps, but it is fed by a 10 AWG 105C wire, I would feel safe with a maximum breaker size of no more than 50 amps.
The lead from your battery to your bilge pump and stereo power bus bar should also have circuit protection. The individual leads to your bilge pump and stereo should also have circuit protection. Determine the bus protection rating based on the total size of the loads and the individual lead protection based on the requirements of the components.
Here is a link to determine the size of the fuse required for your ACR.
Hope this helps,
Kevin
Hi Kevin,
Thank you very much.
I only have one question. The outboard is directly connected to Bank 1. Why do you say that the fuses between the batteries and main switch will blow if the switch is on C?
Best,
Horia
Hi Horia,
If the battery switch is in the both position, the batteries are connected in parallel. The engine will try to start from both batteries and blow the fuses.
Thanks
Kevin
Hi Kevin,
I’m working off the attached diagram and am wondering if you know where I can get a diagram for the boat wiring connections in the dash. I’m using a stern drive drawing were I will be bi-passing the ECM and Trim components. I swapped a 4.3 into a Shamrock (Inboard)
I can probably figure out most of the plug connections. My concern is the Red/Purple and the Purple wires on the Plug. Where are they connected in the dash?
Thanks for any Help
Phil
Hi Phil,
The Red/Purple is the ignition feed wire. It provides constant power to the ignition switch. This is usually connected to the B post on your key switch. I would recommend adding an in-line fuse or circuit breaker near the key switch. According to your boat wiring diagram, it is protected by a 50 amp breaker on the engine and most key switches are only rated at 15 amps.
The purple wire is the ignition wire. This is usually connected to the I post on your key switch. Your instruments are also powered by this wire.
Hope this helps,
Kevin
Hello Kevin,
I recently purchased an AFI 38000 2 speed wiper motor for my boat.
My boat doesn’t have a wiper, but has switches and wiring already. The problem is my boat wiring is for single speed wipers with Carling rocker switches for port and starboard with 3 prongs, grd,+ power,load- on-off.
I was wondering since I don’t have a heater if I could use that switch for the wiper. It is an ON-OFF-ON switch with 4 prongs, grd, load A, + power, load B, and it has a light built in it. I don’t know if I should connect the park wire to the + terminal, I’m afraid there might be a draw on the battery all the time.
If I can’t use that switch, do you know what switch I should use? I’d like to stick with the same design as the rest. Any help would be greatly appreciated.
Thanks,
Larry
Hi Larry,
You can certainly use your heater switch for the wiper. Connect your park wire to the + terminal and your speeds to A and B. If you connect both wipers to the same switch, they will not shut off properly. The speed wires need to be independently wired to keep them from feeding back.
If you want them on the same switch, I would use a DPDT switch like this one. It will allow independent switching of both wipers.
Hope this helps,
Kevin
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