Hello Kevin,
How do I find an engine harness?
I am looking for a boat wiring harness for a 1981 Mercruiser model 470. I would like to get the proper one as I am mechanically challenged but can follow instructions well.
Is there any chance that you can help me out and point me in the right direction.
Thank you.
Benny
Hi Benny,
My recommendation would be to look at eBasicPower. They have a large assortment of engine harnesses for Mercruisers.
Kevin
Kevin,
I have a houseboat with 30 amp shore power and want to change it to 50 amp. How do I do this correctly?
I know that I should get a certified electrician, but i can’t afford one, as I am on a very limited budget. So, I’m asking for your boat wiring expertise. Please send me anything you can.
Thank you in advance.
Carl
Carl,
Upgrading to 50a/125v would require at bare minimum the following:
Without seeing the exact configuration of the boat, I am not sure what is would be needed, but it won’t be cheap. And, if you should go ahead, I would recommend having an electrician inspect your work before turning it on.
It may be simpler and less expensive to add an additional 30 amp shore power system to accommodate your additional loads.
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,
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
Kevin,
I own a 1988 265 Baja. My question is “ Do I need a shore power system?”
I would like to pull up to a dock and use the radio, fan, and fridge on my boat without draining my batteries.
Do you know of any marine electrical system I can plug into the dock that lets me use the features of my boat without running down the batteries?
Sincerely,
Darren
Hi Darren,
The Marine Shore Power Systems from our partners at EzAcDc were designed for your application. Here is a post that I wrote a while back that gives you an overview of the system.
In your specific application, you can use the unit’s exposed AC outlets to power your fan or tv and the hidden outlets to plug in your refrigerator and your battery charger. If you do not have a battery charger, I would recommend a potted, ignition protected unit like the ones from Guest.
Not only will you not drain your batteries while at the dock, you will recharge them. Another big benefit is that you can also purchase less expensive AC devices to use while at the dock instead of expensive DC units. My Walmart does not sell DC 13″ flat screen TV for less than $200, but they have plenty of choices that are AC powered.
The installation of this system is simple. You simply cut a round hole for the shore power inlet and rectangular holes for the AC panel and outlet.
Please let me know if you have any questions,
Kevin
Kevin,
Our marina outlets are 30 Amp with breakers. When I showed my new marine shore power system to our marina people, I was told it didn’t meet the standard because it only has 20 amp circuit protection.
Do you know if this is correct and does anyone sell panels with 30 amp circuit protection?
Thanks,
Wally
Hi Wally,
Their interpretation of the ABYC/NMMA marine electrical standard is backwards. 
Your marina has 30 amp breakers at the dock and standard 30 amp shore power inlets. A standard 30 amp cordset plugs into the receptacle at the dock and into the 30 amp boat side inlet. The wire from the inlet to the panel is sized for a 30 amp system. All components up to this point can withstand the 30 amps that the dockside breaker could supply.
The outlets in your new panel are rated 20 amp. If it had a 30 amp breaker on the panel instead of the 20 amp, then the panel would not meet the standard because it would have too large a breaker for the components. If it had additional circuits, then the panel would have a 30 amp main and branch circuits with breakers. Since there is only one circuit, it includes a 20 amp dual pole breaker to provide appropriate circuit protection for both the ungrounded (black) and grounded (white) power wires.
Here is a copy of ABYC E-11, the boat wiring standard that your marina is referencing. See page 20 section 11.10.2
Hope this helps.
Let me know if you have any questions,
Kevin
Kevin,
I have been thinking about corrosion, road salt and +/- ground systems in relation to rust and basic electrolysis. It is interesting that marine electrical has already addressed these kind of issues.
So, would it be possible to build a custom wiring harness for a VW Beetle that would bypass the body ground a’la boat wiring?
Thanks,
Scott
Hi Scott,
Boat wiring harnesses avoid body grounds for two reasons:
If you built a harness for your Beetle, you could certainly run individual grounds back to a ground bus instead of using the car body/frame. It would nearly double the amount of wire required for your project, but you would potentially eliminate electrical circuit problems caused by corrosion.
Kevin
We received the following email from Jack about a problem that he is having with his Aqua Patio pontoon:
I have an on again off again electrical problem.
The boat is pontoon, Aqua Patio. When boat was purchased the live well in rear had a factory problem. the live well leaked over the switch mechanism; the boat yard rewired the system to a console accessory swich. It worked for a few years but I am convinced it is a ground problem.
As soon as the motor receives current it works at a very low speed (not enough to pump). The motor works when placed across the battery directly. The voltage is 12 volts at the motor when turned on. When the motor is hooked up and tested it may or may not work for a minute. When motor is disconnected and the voltage remeasured the volt reading is somewhere between 2-6 volts. I have voltage at the console but the same senario occurs when I connect and reconnect motor.
The boat is still out of the water so it is easier to track wiring. It is so many splices because of the rewire that I hate to start cutting wires to isolate. The port and starboard rear courtesy lites I think do not work which are connected in the circuit. Cell phone or portable courtesy lite receptacles are in the circuit (have never used but don’t think they work). The old switches that were part of the courtesy/live well circuits are disconnected and by-passed.
The new wiring to the console is blue to ground, the hot is brown. The new circuit is connected to the black in 2-3 different places, of course, difficult places to get to, so dismantling is necessary.
Can you give me a starting point since it is difficult to trac this by yourself? Is there an isolation proceedure that can be done without cutting all the wiring?
Thanks.
Jack,
This is a common occurrence on boats that are made of metal. Godfrey Marine, like every other pontoon builder, does not use the metal framework on the boat as a ground. This helps prevent stray current corrosion (galvanic corrosion), but causes strange ground problems like the one you are having.
Another problem that occurs on pontoon boats is when the boat wiring harness is not properly secured to the underside of the deck. Even if properly secured, wires can be damaged even under normal use, e.g., the wires could be caught by the trailer or perhaps damaged during a “stunt docking” maneuver. Whatever the cause, the boat wiring may now be able to make intermittent contact with the metal framework of the boat. While the resistance is high enough to not trip the breaker or blow the fuse, it can still cause extremely low voltage readings under load conditions.
The best solution to your problem is to run two new wires to your live well pump. Disconnect the existing wires. Connect a new ground wire from the negative of the live well pump (usually black wire) to your battery negative or a negative buss near the battery. Connect a new live well power wire from the positive of the live well pump (usually brown) to the accessory switch on your console. I would recommend using at least a 16AWG good quality tinned copper boat wire.
This is my simplest solution to your situation.
Good luck,
Kevin
More great boat wiring advice from EasyAcDc.com…
Any boat built to NMMA (National Marine Manufacturer’s Association) standards has circuit protection for its boat wiring system. These breakers/fuses are specified to provide adequate amperage for all standard equipment. And, the original boat wiring is sized for the factory installed system.
Problems occur when the boat owner or dealer begins to add other items.
The best and safest position to place your circuit protection is as close as possible to the source of power (battery or distribution panel). For example, a new fish finder is added to the helm of a boat. There isn’t an obvious way to splice in the existing boat wiring to connect the power and ground wires. The solution is to run a new pair of wires to the battery. The fuse for the fish finder needs to go as close as possible to the battery. The fuse is protecting the fish finder and its wiring. If the fish finder has an internal fault, the fuse will blow. If the wire between the fish finder and the battery gets damaged, the fuse will blow.
If the fuse is installed close to the fish finder, then in the case where the wire is damaged between the fish finder, the wire will burn instead.
Circuit protection is also very important when adding additional charging sources. This new charging source is considered to be a source of power that needs circuit protection. If it is not a “self limiting” device, circuit protection is needed at both ends of its positive output wire. Most chargers are self limiting.
For example, let’s say that a solar battery charger is added to boat. It has 4’ long leads with an inline fuse 7” from the end of the positive lead. The boat owner needs to add 8’ of wire to allow the charger to be connected directly to the battery. As long as the wire doesn’t get damaged, this setup will work fine.
Problems occur when the wire gets damaged. If the wire is damaged between the charger and the inline fuse, the self limiting battery charger will shut down, and the blown fuse will limit the output of the battery. If the wire is damaged between the inline fuse and the battery, the battery will continue to discharge until it is depleted or the shorted wire has completed burned up. This usually results in a fire.
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