Total Rewire Advice

[woody619]

Hi,
I just got my first project boat. 1969 Mercruiser 160 inboard. 22' tri hull, cuddy cabin. The first project I want to take on is to redo all of the electrical. It's a mess.

1) Does anyone have a recommendation on a marine electrical manual to help me out? So many I don't know what to choose. Lot's of mixed reviews on the books.

2) Also I want to order the parts beforehand. Can anyone recommend how many 100' spools of what colors and gauges I should buy to get it done? I read over the wiring diagrams but I couldn't find what gauges to buy.

Any help would be appreciated. Thanks

 

[trendsetter240]

Re: Total Rewire Advice

Hey woody, welcome to iboats!

What is it that you are rewiring; the engine electrical or the boat?

When starting any project like this I'd recomend drawing it out first. Then take your tape measure out to the boat and measure all the lengths of wire runs you need to make. This will give you a good idea of how much wire you need to buy.

As for colors, lots red. If you will have any AC wiring on the boat than you should use yellow for the DC ground cables so as not to confuse with the black AC lines.

Cheers.

 

[Silvertip]

Re: Total Rewire Advice

My suggestion is before you start buying anything you do a little more thinking on this project. First, understand that there are two wiring systems on a boat, not just one. The engine harness runs from the engine to the control box at the helm. The other system is the power feed from the battery to the fuse or circuit breaker panel. What book you buy is of no consequence since 12 volts behaves the same way regardless how it is explained and illustrated. Current flows from the positive terminal of the battery, to the fuse panel, to the switches, to the devices, and then back to the battery negative post. Next, you need to determine what gauges you want. Note I said "want". Some you may not want but actually "need". On any boat a bar minimum in my view is a tachometer, a voltmeter, engine temperature, and for outboards a water pressure gauge. If you can see the engine from the helm you don't need a trim gauge. With the proliferatin of GPS units (hand held or permanent mount via fish finder) you don't need a speedometer. Hour Meter is useful for service interval determination. Gas gauge is certainly needed if you can't see the amount of fuel in the tank. So all of this will determine how much wire, what size wire, and what color wire you need. When you decide what you need powered, draw a diagram or look at the sticky at the very top of this forum.

 

[woody619]

Re: Total Rewire Advice

This is an awesome site. Thanks for the info guys. I'm going to buy the book tomorrow and will use your diagram silvertip. Looks like a good one to go with.

I will start with the boat rewiring and want to do the engine to. I'll just focus on that one first.

I'll plan take the time, measure and plan it out. I'll keep you posted... with questions, i'm sure. Thanks

 

[woody619]

Re: Total Rewire Advice

I'm planning it out. Sorry I'm such a newbie. But what would an unswitched accessory(s) be? How do you guys have your setup out there?

Just bilge pump? Gauges maybe?

This is what I've thought of so far... am I making it too complicated? Each black dot represents a switch...

? Stern Lights
? Anchor Lights
? Navigation Lights
? Deck Lights

o Instrument Lights (For Gauges, Finders, Radio)
​

o Deck Light​

? Instruments

o Radios ? VHF & SSB​

o Gauges​

o Finders​

o Depth​

o GPS​

o Stereo​

? Livewell Pump
? Trolling
? Bilge Pumps


I'm going to pick up a book today, just excited...

Thanks

 

[Silvertip]

Re: Total Rewire Advice

Yes -- you are already way off base. The nav light switch (one switch) controls the nav AND anchor light. This switch is typically a three position On-Off-On switch. In the up position it turns on BOTH the bow and stern lights. In the down position it turns on ONLY the stern light. Why? Because when you are stationary (as anchored) you must have only hte ANCHOR light on so that people know you are not moving. when under way both bow and stern lights must be on so they can tell which direction you are going. You don't need a depth switch or gauge since the locator has that function built in. Anything with a switch on it does not need another one. Your radio for example has an ON/Off switch. You don't need another. People get switch happy when doing rewires which is why I suggested lots of thinking. Gauges do not need a switch. They get power from the Accessory "A" terminal on the ignition switch. For your I/O use the "I" ignition terminal. You don't need a switch for a trolling motor as it already has one. Besides -- a trolling motor draws 40 amps or more and would fry a pretty dash mounted rocker or toggle switch. The livewell and bilge pump do require a switch. Unswitched accessories simply means the device has no on/off switch built in -- like a bilge or live well pump. A GPS has a built in switch so it doesn't need one. See what I mean about the importance of planning. This just cut the number of switches you need by about 2/3.

 

[woody619]

Re: Total Rewire Advice

Thanks Silvertip, I feel like I get it now. I really appreciate it. I'll have to figure out the rest doing it. A couple more quick questions so I can finalize my diagram, they might sound stupid. My sketch diagram is attached.

1) On the switched devices, does the ground go through the switch or is it direct from the device to the ground. Direct to ground right?

2)I guess the only switches I need is... Am I understanding the wiring of the Nav & Anchor light correctly

? Lights

o Nav / Anchor (Off-On-Off)​

? Bilge
? Livewell


3) Also what gauge wire do you think I'd WANT not need? 6 or 10 seems to be what I've been reading. What would you use?

 

[Silvertip]

Re: Total Rewire Advice

Diagram is too small to make out all the details. Ground wires NEVER go through a switch although a switch with an internal indicator light does have a ground terminal. That terminal however has nothing to do with turning the associated device on and off. It is simply for the light.

Here is a simple, one circuit diagram:

Most circuits require nothing larger than 16 gauge wire. You troller however requires 6 or 8 gauge depending on its current draw and length of the run from the battery to the troller. You do realize the troller needs it's own battery?

 

[woody619]

Re: Total Rewire Advice

Sorry, here it is bigger. Yes, I figured out I need a seperate battery for Trolling motor ... Does the lighting switch setup look right?

Thanks Silver! I came here a couple days ago knowing absolutely nothing about marine wiring, now I feel like I can do it... figure it out anyway...

 

[bassfearmee]

Re: Total Rewire Advice

I rewired my Tracker last year because the previous owner applied the negative cable to the positive side of the battery and fried everything. This is what I have:

Anchor/Nav rocker (three position switch, Off/Anchor/Nav)
Bilge (for the bilge pump only)
Aerator (for the aerator pump)
Accessory (for radio/fish finder/)
Cabin Lights (for all deck/cabin lighting)

Each rocker has it's own dedicated fuse that's accessable above the switch.

Hope this helps,

Bob

 

[4JawChuck]

Re: Total Rewire Advice

Just a quick note;

All marine termination ends are heavier duty than the common automotive cousin, most are either solid copper with a zinc plating or at least double the thickness for corrosion resistance. I had a lot of trouble finding them in my area until I went to an electrical wholesaler who ordered what i needed from a catalogue, he knew exactly what I wanted where the marine dealers obviously had their own supply just weren't willing to sell to me at the counter.

I used welding cable for battery connections but its only acceptable if its a fresh water application, use the stranded zinc plated stuff for salt water...it will last a lot longer. BTW welding cable is rated for "wet area" usage, make sure the wire you use has this designation...its worth the extra expense.

 

[woody619]

Re: Total Rewire Advice

I'm questionable about my lighting switch setup... Does that on-off-on switch keep the anchor light on all the time when in both of the on positions? and switch from stern to nav when depending on which way it's switched. I read it in this article on silvertips diagrams... (In my diagram, I have 2 switches for lights, is it just supposed to be 1?) Am I missing something?

From this article..
http://forums.iboats.com/showthread.php?t=313954&highlight=rocker+bilge

 

[4JawChuck]

Re: Total Rewire Advice

Anchor light is on at all times the lights are on, only the bow light is switched on and off in the different "on" positions. You can use two switches but one single pole, double throw switch is more common, sometimes known as a SPCO/SPTT switch where the centre position is off. You just jumper the anchor light to both throws to get power in either position.

http://en.wikipedia.org/wiki/Switch

 

[fishrdan]

Re: Total Rewire Advice

Once you figure out what you need for wiring and termination, look at this place for ordering your supplies. they have "marine" grade stuff at Home Depot prices.

http://genuinedealz.com/

The gauges will need 2 power sources, 1 to power the gauge and another for lighting. the lights can be run off your nav light switch so that when you have the bow light on for running at night, the gauge lights will be on at the same time.

Look on Ebay for the switches, sometimes you can pick up a complete new switch panel from a manufacturer and then scavenge what you want off it, same can be said for the gauges too.

For the courtesy lighting, look into LED rope lights. You can mount them up under the gunwale or what ever is convenient and they throw of a lot of light. At least plain LED courtesy lights as the draw little power.

Question on the nav lights, you show surface and mount and pole mount, which are you going to use?

Before you get too far in planning, get a copy of the wiring color codes for your engine and marine wiring, here's one for marine wiring. The I/O forum should have a copy of the engine color codes in one of the downloadable manuals.

http://www.glen-l.com/weblettr/webletters-5/wl44-wiring.html

I just noticed you had an I/O. For the engine, see if you can get a cable or wire harness that is prebuilt. I doubt you will find a new harness that's an exact match for the old I/O, but you might stumble across a newer harness that you could adapt. It might have an extra wire or 2, but at least it would be a nice harness with quick disconnects, important if you ever have to pull the engine out. I had an ol' 73 Mercruiser and a lot of the wiring was pretty dry rotted, so I'd look at replacing all of your wiring if possible.

Good luck!

 

[woody619]

Re: Total Rewire Advice

Man, thanks for the great info guys.

Those prices are way cheap for the wire... unbelievable...

I show surface and pole mounts, because I thought I saw pole mounts on the sides, but they're actually pole holders. I'm going to cut holes and do surface mounts since that's the case. I guess it's never been in the ocean.

Ok, so I'll do that regarding the lighting switch... 1 switch, anchor light connects to both and add a dash light on the nav side.

Also I'll look into those LED rope lights too. Looks like I'll be adding a switch for onboard lights...

One more question about the lighting setup... can I daisy chain positive from one light to the other? or will an out bulb cause everything after it not to work? Should I line each light directly positive? Thanks

 

[Silvertip]

Re: Total Rewire Advice

You show a ground wire on the ignition switch which for an I/O is not present. Remember what I said about switches and grounds? The ignition switch is in the ENGINE harness -- not the BOAT harness. It doesn't belong in this diagram. Remember what I said about two electrical systems? The gauges are not wired correctly either as they are powered by the "A" (accessory) terminal on the IGNITION switch -- not by a separate dash switch or from the fuse panel. They can get ground at the fuse panel but they should get their ground through the engine harness. Why? Because if there is a ground issue, electricity will get to ground any way it can. Therefore if the engine negative battery cable is loose and you hit the key to start the engine, the starter will use the gauge ground to get back to the battery. That wire and others in the area will go up in smoke in a heartbeat. The gauges are protected by a fuse at the ENGINE via the engine harness. For the engine harness you need to visit the I/O Forum, go to the stickies and download a manual for your engine and outdrive. You can use two separate switches for NAV and ANC lights but why would you when one will do nicely. A three terminal switch needs a diode and six terminal does not. Tell me which one you will use and I will provide a diagram (or you can use the SEARCH) function as both diagrams have been posted dozens of times along with descriptions how either is used and wired. If you want to go switch crazy, the courtesy lights should be on a separate switch. Why would you want them on just when the NAV lights are on. Wouldn't you want independent control of them? You show all of the grounds going to various terminals on the fuse panel. ALL grounds go to the GROUND buss on the fuse panel. The points you show are all HOT or LOAD side (+12 volt) terminations. The picture I posted earlier of the single circuit shows the ground bus on a typical fuse panel. Lastly, there is a difference between a schematic diagram and a wiring diagram. What you have shown is mostly "schematic" orientation since it does not pay attention to orientation of components. For this project you really need to make a "wiring" diagram which positions the bow light at the top of the page, the stern light at the bottom of the page, the fuse panel, switches, locator, etc in the middle and the bilge/livewell pumps at the stern. Now connect the wires where they need to go so you can actually build much of the harness OUTSIDE the boat.

 

[woody619]

Re: Total Rewire Advice

Thanks Silvertip,
I just got confused by the picture of the fusebox I had a picture of. It had a fuse labeled terminal, then I heard you say terminal then I for whatever reason connected it. Now I understand it's part of the Engine electrical.

I did find your schematic ref'd in the article below for the switch. Just not clear to me I guess was in the switch diagram how the anchor light was connected, but I think I got it now.

I'm questionable about my lighting switch setup... Does that on-off-on switch keep the anchor light on all the time when in both of the on positions? and switch from stern to nav when depending on which way it's switched. I read it in this article on silvertips diagrams... (In my diagram, I have 2 switches for lights, is it just supposed to be 1?) Am I missing something?

From this article..
http://forums.iboats.com/showthread.php?t=313954&highlight=rocker+bilge

Thanks for making everything so clear to me. Now I think I know I'm ready to work on my wiring diagram.

 

[Silvertip]

Re: Total Rewire Advice

The word "terminal" means "connection". On any device it is either a spade connection (a slip on), ring terminal connection (a screw terminal), or a solder connection. The ends of a battery cable are either ring terminals on both ends or a standard post-type battery cable clamp on the battery end and a ring terminal on the other. When you "terminate" a wire you add the appropriate connector and connect it to whatever device it goes to.