Simple wiring questions for my first Mod!! Please help!

Hello everyone, i'm doing my first full boat mod and am going to begin the wiring here in a couple of weeks once i have purchased everything i need for it. Just need batteries, wiring, connectors, and to build a console to put my switch panel on and i'm ready to go. My biggest question is should i go with marine grade wire? Or is buying a rubber coated extension cord type deal with 2 insulated wires inside ok to use? I have conduit running the length of my boat already so my long runs from trolling motor and nav lights will be inside of that. My next question is what gage wire should i be using for all of the following items:

-Trolling motor
-Depth Finder
-Nav Lights
-Courtesy lights (12v rop lights and led lights)
-Livewell Pump
-Stereo system

I was hoping to find a happy medium and only order one type and gage of wire in a bulk roll to save some money. Let me know what you guys have for input. Any help would be great here. Thanks everyone! I am new to wiring things myself so i want to do it right the first time.!!!

I've owned a marine service business for the last 15 years with a lot of my work being electrical, so I'll try to refrain from writing a book here and still give you some basics to start with.
You will need a good pair of wire cutters/strippers/crimpers. Klein makes a good pair for around #15 and you can get them at Home Depot or Lowes. Stay away from the cheapie kits that come in a plastic box with stripper/crimper and an assortment of connectors. You will get terminals that you will never use, plus the tool and parts are cheap. Trust me, wiring is not where you want to go cheap, but you don't have to break the bank to do it right. The idea is to only do it once and forget it.

Wire type - Marine wire is the wire of choice because it's tinned. That means it solders easily if you want to do that and it resists corrosion. That said, in ND, I don't think salt water/spray is going to be an issue, so just use a good stranded copper wire. HD and Lowes sells it by the foot or by the roll. There is a specific color code system for boat wiring that uses different colors for different applications, but on a project of your size, you can get away with using red for hot and black for ground/neg.
Don't use extension cord/zip wire. It's poor quality and being all one color, it will be very difficult to keep track of hots and grounds and you'll waste a lot of time tracing wires back and forth to see what is what.

Wire size - The instructions for items you are installing will tell you what the amp draw is for that device. Go to West Marine's website and in the electrical section, there is an advisor that is a chart to help you select wire size. It is pretty much self explanatory. You will measure the length of the wire run(both ways) you are going to use and you want to select the wire size that gives you a 3% voltage drop for the length of wire used. There is a matrix for a 10% drop. Ignore it, as it is only for non-voltage critical, high load devices like motors and winches. When in doubt, go up one size. No one ever caused a problem ny using wire that was too big.
If you don't want to deal with a lot of different wire sizes, #14 may be overkill for some things, but will cover everything you want to do except the trollong motor. That is probably going to require #8 wire minimum.

Wire Connections - A good crimp connection will last a long time, and you can go as far as you like with these. You can solder, but it's not absolutely necessary. Sometimes I do, sometimes I don't. When I crimp, I cut the little plastic sleeve off of the connector, crimp it and then use heat shrink to seal it against moisture. It makes a really nice looking connection. If it's a connection that's likely to get wet, I'll use the heat shrink that has the adhesive in it that melts when it gets hot. Heat shrink is nice, but not absolutely necessary. If you don't want to go the heat shrink route, then get a can of liquid electrical tape and paint any exposed copper wire. I also really like to use wire loom. It's a plastic tube with a slit in it that lets you encase all of your wiring. It can be secured and keeps all of your wiring in one bundle, plus you don't snag stuff on wires that are hanging loose..

A tip on connecting ground wires - My pet peeve is to go to work on a customers boat and find a nest of wiring where everything has been run back to the battery posts. When you disconnect everything to charge or replace the battery, wire go everywhere. Use a sort piece of the same wire you'll use for the trolling motor and go from the negative post to a terminal strip. Then, connect all of the ground wires to that and have only one wire going to the battery's neg post. You'll thank yourself for doing this later.

Electrical Tape - Don't use it unless absolutely neessary. it gets stick in the heat and turns into a gooey mess. Tie wraps arecheap and look a lot nicer.

A lot of this sounds like extra work and it is. But, it insures that everything works everytime you hit a switch, and you don't have to look at a sloppy installation everytime you get in the boat. If you have specific questions, PM me and I'll be happy to answer all that I can. One thing I did not cover is fuses and fuse panels. There is a lot of info on that in this section of the Forum.

Finally - My back ground is with larger boats and a lot of what I said is generic, basic wiring practice. Go back and read all of the electrical threads here. Some of these guys have done some really nice electrical jobs on their tins. Make it a fun project and enjoy the results for a long time.

I bought all my wire from HD and soldered all wire to wire connections and crimped all connectors on. I then used marine heat shrink on all connections. It's cheaper if you buy by the roll.

Good point. Simply soldering does not provide a good mechanical connection. if you are going to solder, you still need to crimp. BTW twist-on top hat connectors/wire nuts are a no-no on boats and trailers. I've seen so many electrical issues on boats, you just can't be too thorough on this stuff. Nothing is more frustrationg than to have to troubleshoot a wiring problem after everything has been tied and tucked out of sight.

Soldering connections makes them more susceptible to corrosion. Liquid electrical tape does not properly seal wiring, and it can even interfere with the connection itself.

Connections should be made with waterproof, adhesive-lined heat-shrink connectors (they're about a dollar a piece at West Marine, but you can buy the same thing a lot cheaper at an auto zone or advance auto parts) Once you crimp the connector, use a heat gun, and the sleeve will shrink onto the wire, making a water tight connection.

There were tests done by ABYC regarding wire connectors. Soldered connections sealed with liquid electrical tape VS. the heat shrink connectors sealed with splicing tape, placed underwater. The tests concluded that the soldered connections were inferior and corroded at a much faster rate.

As stated, electrical tape, in either roll form, or in liquid form, is about worthless in a marine application. Instead, go to Home Depot, and get a couple of rolls of 3M SPLICING TAPE. This is the same type of tape used to splice the main supply lines going to your house. It's rubberized, and has a backing. As you stretch and wrap it, this tape sticks to itself, and it bonds very well. Unlike electrical tape, which gets gooey, then loosens up, splice tape actually hardens, and it's very difficult to remove...you basically have to split it with a razor to get it off.

For bundling wires, get a roll of 3M FRICTION TAPE. This tape is more cloth-like, and it's what you see used in wiring harnesses. It's also useful for making a wrap at the ends, and every few feet along a split wire loom, to keep everything bundled together.

For everything but the trolling motor, you should be fine with #14 or even #16 wire. It depends on the amp draw of each device, and the length of the run.

For the trolling motor, definitely a heavy gauge, like #8, or even #6, again, this is determined by the amp draw and length of run.

If you want to color code your wires, wrapping with electrical tape every few feet will work, but that tape can come off, then you're guessing. It's better to mark them with paint.

And finally, if you want to simplify your connections even more, check out diyautotune.com and get a weather pack kit. This kit has the delphi multi-pin connector kits, complete with the male and female pins, and the seals, for all gauges of wire, as well as connectors for 1, 2, 3 and even 4 wires. This will make your wire harness professional looking, and will make it easier to disconnect things without having to cut and re-splice wires.

When I re-wired my G3, which came from salt water and was a mess, I used #16 for everything except the VHF and I used #14 for that because of the current draw on transmit. The trolling motor was wired with #8, but since I had to drill rivets and pull the side panel to get to it, I figured for the small difference in price, bigger was better and I went with #8. I do prefer the adhesive lined heat shrink, but the liqid tape when used correctly is better than nothing. A heat gun is not always in everyone's tool box, and unless you do a lot of this stuff, most people don't have one laying around. The main thing is to keep moisture from wicking under the installation and causing corrosion. If that gets bad enough, you can't cut back enough to get clean wire for a repair and you end up having to pull new wire.
Also, I use AWG wire and not SAE. My G3 was factory wired with SAE wire. I'm not going to get into the diameter and conductivity differences between the two because I don't know it and don't want to waste time researching it, but size for size, the AWG wire appears to be larger and if that's the case, will give better conductity. Also, marine connectors are sized for AWG wire.

I agree with the idea of running grounds to a common bus bar rather than to a big knot of wires at the battery. I've seen many "interesting" wiring jobs done by guys who wanted to save a few bucks and ended up paying more to get straightened out. B. Landry is right-on with his advice to not get penny wise and pound foolish when wiring. If I can weigh in with my 2 cents worth, I'd suggest that you draw out all the circuits you need and use the West Marine wire size calculator to figure out the correct wiring.

Since I'm getting ready to wire my boat (a MonArk 1448 Jon), my question is about conduits on the boat. Am I better off putting in PVC conduit for my front-to-back runs, should I run the wires just bundled with wire wraps, or should I use flex conduit? Regardless of what I do, I'll run three or four waxed cords in parallel with my wiring in case I have to pull anything else in the future. Advice, anyone?

I think most people use PVC for conduit. I ran my wires up front through the gunnel which has worked well.

Good advice from all. Bob Landry, I am surprised based on your statement of not cheating out on electrical that you would advice the use of liquid electrical tape, especially since you then say it is a 'better than nothing' product. Despite that gaff most of your advice seems pretty great.

You don't need a heat gun in your arsenal to use heat shrink wrap - you can also use heat from a lighter, a soldering iron or even a hair dryer in a pinch. Just don't hold the flame on the tube or touch the soldering iron to it.

Though you can just bundle the wires for the long run or use split loom I would recommend using a PVC conduit or flex conduit - it looks even cleaner and provides a little extra protection.

I use this stuff on all my connections......It's like the 3m stuff stated above....comes in all colors if you going to color code your connections and such.....We sell it where I work, or you can just order online. My buddy replaced a bilge pump that we used this stuff on, after a couple of years in a saltwater bilge environment.....both connections looked brand new. Highly recommend this product it can seal a leaky hose too....
www.rescuetape.com

Thanks for all the help guys. The costs of all the wiring and accessories for my boat is really starting to add up. I'm in about 1200 for accessories right now. I have a couple more questions for you electrical guys. I bought a 2 bank on board charger. I want one trolling motor battery (deep cell) and one cranking battery. My motor has an alternator so my cranking battery will hook up to that as well as the rest of my accessories. My question is as follows: will it hurt my cranking battery to be hooked up to my on board charger? Will the set up i'm thinking up work here. trolling motor on deep cell, everything else on cranking battery and 2 bank charger hooked up to both? let me know what you guys think will work. I start next weekend on all the wiring. Thanks

Jawhee13 said:

Thanks for all the help guys. The costs of all the wiring and accessories for my boat is really starting to add up. I'm in about 1200 for accessories right now. I have a couple more questions for you electrical guys. I bought a 2 bank on board charger. I want one trolling motor battery (deep cell) and one cranking battery. My motor has an alternator so my cranking battery will hook up to that as well as the rest of my accessories. My question is as follows: will it hurt my cranking battery to be hooked up to my on board charger? Will the set up i'm thinking up work here. trolling motor on deep cell, everything else on cranking battery and 2 bank charger hooked up to both? let me know what you guys think will work. I start next weekend on all the wiring. Thanks

Click to expand...

It will not hurt to have the charger hooked to the cranking battery. Run everything else off of the TM battery. I would not have anything draining on the cranking battery. Worst case, you can always limp back to the dock without lights and a TM if you have to, but I wouldn't put anything on the CB that would put any kind of a drain on it. It needs to be dedicated to the motor for starting.

You might want to look at the Blue Sea Automatic Charging Relay. It connects both batteries when there is a charging source. it would allow you to "top off" the TM battery while you are running to the next spot. Every little bit of charge helps.