Fishing Boat Wiring

Fishing Boat Wiring Questions?

November 29th, 2010 by Kevin Hannula

This site attempts to answer Smokercraft. America's first family of boating your questions about fishing boat wiring and marine electrical techniques, concepts, and products. We get lots of mail from folks in mid-project or who are just curious about their boat’s electrical setup.

There are loads of post already on the site which we hope you will browse through. If you’re trying to track down info about a more specific category, please use the search box in the upper right of this page or check out the list of various subjects farther down on this page.

If you aren’t able to find the info that you need to complete your particular fishing boat wiring project, please send us an email at boatwiring@gmail.com.

Thank you for visiting. We look forward to hearing from you and hope that you will be able to come back often.

Posted in Uncategorized |

Bow battery? Stern Switch?

May 15th, 2012 by Kevin Hannula

Hi Kevin,

I want to add a second battery at the front of my 18 foot pontoon boat to run a trolling motor that will mounted on the front.

I would like the main motor, a 70 hp Evinrude, to charge the trolling motor battery.

What gauge of tinned marine wire would you suggest? I assume stranded wire would be best.

Thanks.

Artie

Hi Artie,

If you want your 70 hp Evinrude to charge both batteries, it may be easier put the second battery at the stern of the boat and connect them together with a boat battery switch system, which you can find our on sister marine electrical site.

This will allow you to select which battery the engine is starting from and also help prevent a dead battery after too much trolling motor use.

Run the trolling motor leads to the rear of the boat and use circuit protection as close as possible to the battery for the trolling motor.

The cables that connect the batteries are short and there is no requirement to have circuit protection on them since that can be used as part of the starting circuit.

Never use the frame of the boat as the path to ground. It will cause SEVERE galvanic corrosion.

Good luck,

kevin

Posted in Batteries, Battery Management, Boat Battery Switches, Boat Battery Wiring, Boat Wiring, Corrosion, Galvanic Corrosion, Ground issues, Marine Electric, Marine Electrical, Marine Wire, Marine Wiring, Outboard Engines, Pontoons, Power Boats, Trolling Motors, Wire Size |

VSR for 24V System?

May 7th, 2012 by Kevin Hannula

Hello Kevin,

The wiring on my fishing boat has a single 12v marine battery to start my boat and run electronics and two 12v batteries connected together creating a 24v system for my trolling motor.

I’ve been thinking of getting a Smart Marine Battery Switch system from one of your retail sites. Will this product charge all three batteries, or is it designed for just two?

Thank you.

Kyle

Hi Kyle,

These VSR based smart battery switches are designed to charge a 12 volt marine electrical system. All of the batteries need to have a common ground for the system to work.

Your 24v boat battery wiring connects the positive of one trolling motor battery to the negative of the other. The smart system would have the ability to charge one of your trolling motor batteries, but not both.

Please let me know if you have any other questions.

Kevin

Posted in Batteries, Battery Management, Boat Battery Switches, Boat Battery Wiring, Boat Wiring, Jon Boats, Marine Battery Switch, Marine Electric, Marine Electrical, Marine Wiring, Pontoons, Power Boats, Smart Battery Switch, Trolling Motors |

Boat Wiring Size

April 25th, 2012 by Kevin Hannula

Kevin,

Thank you for your answers to so many electrical questions. I plan to redo my fishing boat wiring and have a couple of questions.

My 1977 18 foot Starcraft has an outboard motor with it’s own circuit and will not be involved in the rewire.

My current marine electrical has a battery in the back of the boat, approximately 16 feet from the fused, marine electrical switch panel.

The old boat wiring is a rat’s nest with each circuit wired individually.

I will be using the standard small boat items: a depth finder, FM radio, bilge pump, navigation lights (bow and stern), gauges and a rear-mounted gas tank.

I would like to run a duplex cable from the rear battery to the switch panel. The total duplex run would be 32 feet and the total amp draw should be no more than 30.

I think I need a 10 AWG duplex cable for the 30 foot run and 16 AWG boat wiring for leads from the switches to the instruments (+) and bus bars (-)?

Does this sound right?

Thank you for any help you can provide.

Teddy

Hi Tom,

I would recommend using my boat wiring size calculator to answer your wire size questions.

Leave the voltage drop percentages in column B and G alone.
Enter the current draw of you switch panel devices in column C and H.
Enter you total wire length run in inches for each device (switch to device and back to ground) in column D and I
Enter your total wire length run in inches for the panel feed (battery to panel and back to battery) in cell 25D – 384 is your guess.
Your wire sizes will be in Column E and J.

Let me know if you have any questions,

Kevin

Posted in Bilge Pump, Boat Battery Wiring, Boat Lighting, Boat Wire, Boat Wiring, Bus Bar, Engine Harness, Gauge Panels, Livewell Pump, Marine Battery Switch, Marine Electric, Marine Electrical, Marine Engines, Marine Wire, Navigation Lights, Panel Rewire, Pontoons, Power Boats, Pumps, Radio, Switch Panels, Voltage Drop, Wire Size |

Mercury Optimax – Boat Battery Wiring

April 16th, 2012 by Kevin Hannula

Hello Kevin,

I have a 17 foot fishing boat with a 2004 115 Mercury Optimax and a 2007 9.9 Mercury kicker. I only have a single cranking battery for both motors.

I was told that my marine electrical setup should have two cranking batteries, one for each motor hooked up to a boat battery switch.

The guy said I could damage the computer in my Optimax if by accident one motor was started while another was running. Would the automatic smart boat battery switch (the one you designed for your sister marine electrical site) prevent that if each motor was hooked up to separate batteries with this switch? How detailed is the marine wiring for this switch?

I really like the idea of this switch. My old boat had a Perko battery switch and I always forgot to switch it back and forth.

Thanks,

Conrad

Hi Corey,

Your system is very common and I have not heard of people damaging computers in this manner. I have, however, heard of people damaging computers by turning the battery switch to the OFF position while the engine is running.

With our smart battery switch system, when either battery is above 13.7 volts, the batteries are connected together. When it drops below 12.8 volts, the switch opens and the batteries are not connected.

If you had your kicker connected one battery and your main connected to the second battery, while charging, the batteries are connected together and they would not be isolated to prevent the situation that you are describing.

The connection is fairly simple and we supply all of the boat battery wiring required with the Smart VSR Battery Switch System.

Please let me know if you have any questions,

Kevin

Posted in Batteries, Battery Chargers, Battery Management, Boat Battery Switches, Boat Battery Wiring, Boat Wire, Boat Wiring, Marine Battery Switch, Marine Electric, Marine Electrical, Marine Engines, Marine Wire, Marine Wiring, Outboard Engines, Pontoons, Power Boats, Pumps |

Navigation Light Short

April 9th, 2012 by Kevin Hannula

Hey Kevin,

I just bought a 1987 Fisher bass boat with a 1989 110 hp Johnson outboard.

The navigation lights had been removed but the light wiring was still running up to the front of the boat. I bought a new Attwood LED navigation light and connected it (pretty sure I did it right) but the navigation light will not work. The white all round anchor light does work when I turn the switch to just anchor lighting and navigation lighting.

I followed the boat wiring for the lights and found that the negative wire was tied into the main negative wire going directly to the boat battery (this was connected). After those two wires meet, it appears the wiring coming from the two is supposed to be connected to a fuse but it was not.

There were two fuses open, a 20 amp and a 10 amp. As soon as I connected it to the 20 amp, the fuse blew. There was a spark when I connected it. I have no clue where to go from here.

Any advice would be greatly appreciated.

Thanks!

Tommy

Hi Tommy,

It sounds like there is a short in your marine electrical between the fuse and the light.

You can either try to trace down the short or replace the wire. Sometimes it is much easier to replace marine wiring than to find the problem. Make sure to use circuit protection at the power source to protect the wire if a short happens again.

Happy wiring,

Kevin

Posted in Boat Battery Wiring, Boat Wire, Boat Wiring, Circuit Protection, Cruisers, Ground issues, Marine Electric, Marine Electrical, Marine Wire, Marine Wiring, Navigation Lights, Outboard Engines, Panel Rewire, Pontoons, Power Boats, Signaling Devices, Switch Panels, Testing, Voltmeter |

Wellcraft Wiring

April 3rd, 2012 by Kevin Hannula

Hi Kevin,

I’m considering a total redo of the marine electrical on my 1984 23ft Wellcraft Sportsman Walkaround.

I have a 200hp Mercury and the engine harness is fine as is the boat battery wiring and the switch wiring.

What I need to rewire is my navigation lights front and rear, anchor light, the two bilge pumps front and rear (with the option of adding one more in the rear) and docking lights also adding a few underwater lights on the transom. I also have a horn, washdown pump and trim tabs. I have one furuno 620 and two gps setups.

What I want to know is if I order a boat wiring harness and switch harness from your sister marine electrical site, EzAcDc, will they cover everything I need? If not any help you could offer would be great.

Thank you

Tom

Hi Tom,

Thanks for considering some of the parts on our retail boat wiring site.

Our boat wiring harnesses contain wiring for an automatic bilge pump, a livewell pump, courtesy lights, navigation lights, docking lights, and a boat horn.

When combined with our switch panels, it is simple to connect additional electronics like your Furuno and your GPSs. Additional bilge pump wiring can be run from the pump to the switch panel.

We offer several boat battery switch systems to fit your needs. Our most popular is the smart marine battery switch system. Your 200 HP Merc will work great with this system.

Hope this helps. Thanks again.

Kevin

Posted in Batteries, Battery Management, Bilge Pump, Boat Battery Switches, Boat Battery Wiring, Boat Lighting, Boat Wire, Boat Wiring, Circuit Protection, Engine Harness, GPS, Horns, LEDs, Livewell Pump, Marine Battery Switch, Marine Electric, Marine Electrical, Marine Engines, Marine Wire, Marine Wiring, Navigation Lights, Outboard Engines, Panel Rewire, Power Boats, Pumps, Smart Battery Switch, Switch Panels, VSR |

Bot Buddies

April 1st, 2012 by Kevin Hannula

Dear Kevin,

Last summer, I purchased a new aluminum fishing boat. It’s great, but I screwed up by “cheaping out” at the last minute. I passed on the trolling motor package and – as you’ve probably guessed – now want to add a trolling motor.

As a long time reader, I know that you are a big fan of Motorguide trolling motors and I’ll be buying one in the next couple weeks. My question concerns the boat wiring.

The Motorguide will be bow mounted, but since I didn’t get the trolling package, the only wire at the bow is a 16 gauge pair for the Attwood LED navigation light. But, according to your boat wiring size calculator, the trolling motor should be wired with 6 gauge.

Is there any way to make the smaller wire work? I hate to start rewiring a brand new boat if I can avoid it.

Thanks.

Sean

Hi Sean,

Since your boat is new, you may be in luck. A lot of boat builders now use Ancor’s new Nanotech Wire. As you’d guess from the name, it uses nanotechnology to solve problems just like yours.

Simply put, Nanotech Wire matches wire size to power demand by moving copper to where it is most needed – sort of a Viagra for marine electrical.

In the past, running a trolling motor on undersized wire caused voltage drops, heat buildup and embarrassing insurance claims. But now, that same temperature increase signals Nanotech Wire to deploy an army of nanobots who quickly rebuild the harness to match the power demand. While at work, these little guys make the wire looks like a python that swallowed a large rat.

Once your harness is properly sized, the same bots then go to work on its insulation so that it correctly corresponds to standard boat wiring colors.

The patented process is called Nanotech Overload Sensing Heat Induced Tranference and it works great. The only time I’ve seen it fail is when there are so many accessories turned on that there is no extra copper available. If this happens a lot, I usually recommend the addition of a copper reservoir to supply additional material as needed.

Have an excellent day.

Kevin

Posted in AC Wiring, Accessory Harness, Batteries, Battery Management, Bilge Pump, Blowers, Boat Battery Switches, Boat Battery Wiring, Boat Lighting, Boat Wire, Boat Wiring, Circuit Protection, Corrosion, Cruisers, Engine Harness, Galley, Galvanic Corrosion, Galvanic Isolator, Gauge Panels, Horns, Jon Boats, LEDs, Livewell Pump, Marine Electric, Marine Electrical, Marine Engines, Marine Wire, Marine Wiring, Multimeter, Navigation Lights, New Products, Ohmmeter, Panel Rewire, Pontoons, Power Boats, Pumps, Radio, Refrigerator, Sailboats, Shore Power, Shorepower, Signaling Devices, Switch Panels, Testing, Trolling Motors, Wire Size |

Radio Requiem

March 26th, 2012 by Kevin Hannula

Hi Kevin,

I have a 19 ft open fisherman and the marine electrical includes a boat battery switch.

Over the winter one of the batteries reversed polarity, and I had the thing hooked up per their diagram. I have removed the bad battery, and have my accessories run to a marine electric fuse block.

My VHF fuse blows as soon as I replace it, and when it blows my GPS cuts off, and will not cut back on for a while. I have wiring coming from the battery red to the positive side, and black to the negative boat bus bar. Everything goes through its separate fuse but none on the fuse block blow.

I have no idea what is wrong. Could it be a bad ground on the motor, or could the radio be blown and have a dead short causing this?

Seymore

Seymore,

It is very possible that there was some internal damage to the radio.

Eliminate all of the boat wiring and connect the radio directly to the boat battery (with an in-line fuse). If it still blows the fuse, the radio is done.

If the radio still works, start tracing the wires that are common between the VHF and the GPS. There may be a bad/burnt connection that resulted from your marine wiring mishap.

Kevin

Kevin,

The radio still blows fuse when hooked up to battery alone.

Could the short in the radio cause the battery to reverse polarity? By the way I ran the battery down to zero, and have it on charge and it is showing a positive charge now.

Seymore

Hi,

The battery should be fine, but I’m afraid that the radio is dead

Kevin

Posted in Batteries, Battery Management, Boat Battery Switches, Boat Battery Wiring, Boat Wire, Boat Wiring, Bus Bar, Circuit Protection, GPS, Ground issues, Marine Electric, Marine Electrical, Marine Wire, Marine Wiring, Pontoons, Power Boats, Radio, Testing, Voltmeter |

Six into Eight?

March 19th, 2012 by Kevin Hannula

Kevin,

According to your marine wire size calculator, I should be using 6AWG tinned boat wiring on my new Motorguide trolling motor.

After running the boat wire, I found that the Marinco trolling motor connector can’t handle any wire larger than 8 gauge. Marinco makes an a adapter, but where the plug is installed, there is no room for it.

Can I splice a short piece of 8 gauge wire on the end of my wiring run to connect to my trolling plug?

Maurice

Hi Maurice,

The 6 AWG marine wire was required to reduce voltage drop in the system. If the run would have been short, 8 AWG would have been acceptable.

With this in mind, then it is acceptable to run a short section of 8 AWG to a junction block and then connect both sets of wires to the studs. This is a common marine electrical practice.

Good luck,

Kevin

Posted in Boat Battery Wiring, Boat Wire, Boat Wiring, Bus Bar, Ground issues, Marine Electric, Marine Electrical, Marine Wire, Marine Wiring, Panel Rewire, Pontoons, Power Boats, Trolling Motors, Voltage Drop, Wire Size |

Fishing Boat Wiring

Marine electrical advice for fishing