# Wiring of a 1980 Catalina 27



## Ajay73 (Jun 13, 2011)

I want to look at my C27's wiring with an eye towards changes/upgrading. Is there an up-to-date wiring plan in the form of something like the attached link posted by maccauley123? I'm just starting to get familiar with the subject of sailboat wiring(I just bought the C27 this past August) and quite honestly some of the wiring diagrams I see are really confusing. I've got a book by Don Casey entitled "Sailboat Electrics Simplified" and it's not bad but the attached link from maccauley123 seems very clear to me, gives some sizes and other information and I believe can form the basis of understanding what I need to do. It's a little thin regarding the engine/alternator circuit but I can probably work through that. I don't plan on putting in a lot of sophisticated equipment/systems, just the basics that the boat came with from Catalina (running lights, cabin lights, knot meter, depth gauge, mast lights and of course engine circuits)but updated with more appropriate wire sizes, terminals, etc. I guess my feeling is that for someone who just wants the basic electrical system to be solid there should be an "off-the-shelf" wiring plan out there. Any help you can be will be greatly appreciated.

http://www.sailnet.com/forums/gear-maintenance/49181-wiring-help-needed.html


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## arf145 (Jul 25, 2007)

I'll be happy for you if someone follows up my reply with a link to exactly what you want, but...I don't expect there is such a thing for you. And of course with a 30-yr-old boat most have diverged from the original. I found Nigel Calder's Electrical/Mechanical book to be a big help. Best you know the reason for the wire size needed for a particular run length and demand anyway.


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## mitiempo (Sep 19, 2008)

The diagram by Maccauley123 (shown below) would not be a great one to follow. It is confusing, the bilge pump is after the main switch when it should have power when the switch is off, the negatives are not clearly defined, and I don't think his second switch is necessary.

As posted by arf above, I very much doubt your wiring is close to original after several decades. I virtually never ask for or look at an original schematic when working on a boat - they are seldom accurate.


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## n8kraft (Dec 31, 2009)

*Catalina 27 wiring*

If you have the original manual that came with the boat it has a simple drawing describing the original electrical layout.







You can get more original manuals on the Catalina 27 website here: C27 Manuals


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## btrayfors (Aug 25, 2006)

I agree with mitempo. In addition to what he said, the wiring size from the batteries and, especially, between the switch and the panel is too small, and the 100A fuses are too small since they're effectively in the starting circuit.

Better start anew.

It would also be good to decide whether you're planning to route all charging sources to the house battery bank and use some sort of automatic charging device (like an EchoCharge or DuoCharge or other) to maintain the start battery, since that decision impacts on much of the heavy DC wiring.

Bill


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## mitiempo (Sep 19, 2008)

I think the best plan is to draw your own schematic. I'm guessing you will have a start battery and a house bank. Decide how they will be charged from the engine. Catalina and most other builders charged through the main (1/2/both/off) switch but that isn't a great plan for several reasons. The better way is to routs all charging, from any source, to the house bank and charge the start battery with an Echo Charge or ACR. The main switch becomes a control for use, not charging - easier to use and simpler. From the main switch output's common post there are feeds to the starter and to the fuse/breaker panel. The panel feed wire should be able to handle the entire panel's load with 3% voltage drop or less. From the panel the circuits - lights, electronics, etc - are branched off to each.

On a 27' boat 14 awg is probably a good choice for many circuits. For deciding on wire gauge this link AWG by wire length/amps calculator
will let you determine the gauge required. The distance is from the source to each load and back. I try for 3% drop or less for everything but lights can tolerate more. The wiring for nav lights and feed to the mast should be 12 awg but it is easy to figure out with the link above. Bilge pump wiring shouls be direct from the battery and not through the main switch. Fuse at the battery for this and fuse the main battery feeds as close to the batteries as possible - ABYC calls for 7" but that isn't always possible.


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## Stu Jackson (Jul 28, 2001)

Here's one that should answer the basic engine/alternator wiring issues. The PP (previous post) shows the downstream DC wiring quite well. This link includes options as well as a very good wiring diagram from this message board.

Basic Battery Wiring Diagrams

The detailed wiring diagram came from this topic, in the Electrical section of this message board:

http://www.sailnet.com/forums/electrical-systems/79919-updating-dc-system.html

If you want sources for more boat electrical systems, try this:

Electrical Systems 101


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## eherlihy (Jan 2, 2007)

The OP asks for the basics. Here they are;

1. Use the wiring size recommendations that Stu Jackson points toward.

2. Follow the ABYC Color code.

3. Make a _working _diagram.

Here is the ABYC Color Code (a lot of this stuff does not apply to a sailboat);









In addition, you ask for how to do the engine / alternator circuit.
Here is my _current _wiring diagram, for my basic charging circuit for my Universal M-25 with the Westerbeke Admiral's instrument panel on my Oday 35;








Not shown in the diagram is that I have an IOTA 30A Charger connected to the house battery.

You can see that in a few places I did not follow the ABYC color code. One example is the starting circuit, which uses a white wire with a red stripe on my boat. Part of the reason is that I could not find any marine grade tinned yellow wire with a red stripe, but instead I used the AWG10 White / Red that the previous owner paid big bucks to have installed by a pro.

Another example is that my negative conductors are a mix of yellow and black. This is because I am slowly changing out circuits, as needed, and as my budget allows. I am not doing a wholesale rip & replace (I would rather be sailing).

However, I have documented the color code that I have used, and that makes it acceptable per ABYC.


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## Stu Jackson (Jul 28, 2001)

Nice diagram. Well done. For the OP: It does, however, if I read it correctly, use the 1-2-B switch as a charging source switch as well as a use switch (see my links above for recommendations for taking the AO to the house bank and NOT the C post on the switch), and does not show the distribution panel from the C post.

Good ideas for showing all the panel gauges and the wiring color codes.


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## eherlihy (Jan 2, 2007)

Yep Stu, you are right. I am using the 1 B 2 switch to control charging and use. 

I use the house bank ONLY (bank 2 a group 27 Trojan) to start, run, and power the DC systems when at anchor. The dedicated starting battery (a WM Starting Battery), is only there as a backup. By the way, my M25 starts fine with the 90A fuse.

I have thought of moving the wire from the C lug to the 2 lug of the battery switch, but the system that I have now is working, and, I have the upgraded Leece Neville 90 amp alternator, which also has a semi-smart regulator. If there is no load, it shuts off before the diodes pop.


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## Maine Sail (Jan 6, 2003)

eherlihy said:


> I have the upgraded Leece Neville 90 amp alternator, which also has a semi-smart regulator. *If there is no load, it shuts off before the diodes pop.*


Who told you that...? The whole idea of sudden load disconnects is that regulators, no matter how smart, simply can't react fast enough, we're talking microseconds for the damage to be done. In an ideal world a voltage regulator could react fast enough but they very often don't. The Leece-Neville reg on the 8MR's is no different. Even Balmar, Ample, Xantrex or Sterling regs will not protect you if you suddenly disconnect the load while charging..

For the OP I would advise getting Charlie Wings book Boatowners Illustrated Electrical Handbook Volume 2. This falls between Casey and Calder and has had the best reviews from customers and friends I've suggested it to. It also follows current safety guidelines.


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## Ajay73 (Jun 13, 2011)

arf145 said:


> I'll be happy for you if someone follows up my reply with a link to exactly what you want, but...I don't expect there is such a thing for you. And of course with a 30-yr-old boat most have diverged from the original. I found Nigel Calder's Electrical/Mechanical book to be a big help. Best you know the reason for the wire size needed for a particular run length and demand anyway.


If I understand the implication of your 30 year old comment right I'm not looking to reproduce the original wiring plan. I was looking for something more up-to-date. And I'm not looking for something special just for me. What I have are just the very most common of circuits. What I liked about the referenced link was that it was clearer than most of the diagrams I see, written for a layman, so to speak. Most of the discussions about wiring seem confusing to me. But maybe I think it's more complicated than it really is.


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## Ajay73 (Jun 13, 2011)

mitiempo said:


> The diagram by Maccauley123 (shown below) would not be a great one to follow. It is confusing, the bilge pump is after the main switch when it should have power when the switch is off, the negatives are not clearly defined, and I don't think his second switch is necessary.
> 
> As posted by arf above, I very much doubt your wiring is close to original after several decades. I virtually never ask for or look at an original schematic when working on a boat - they are seldom accurate.


First, I don't know how you guys are getting the idea I'm trying to reproduce the original wiring plan. I'm looking for something UP TO DATE. What I liked about the maccauley plan was that it made more sense to me. He may be wrong on some of the things but I liked the way he laid out the distribution panel and the buss bars., etc. And isn't his bilge pump wired so that it goes directly from the battery to the pump (through a fuse) so that it is always on and not on only when the battery switch is on.


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## Ajay73 (Jun 13, 2011)

n8kraft said:


> If you have the original manual that came with the boat it has a simple drawing describing the original electrical layout.
> 
> 
> 
> ...


Not looking for the original electrical layout.


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## Ajay73 (Jun 13, 2011)

mitiempo said:


> I think the best plan is to draw your own schematic. I'm guessing you will have a start battery and a house bank. Decide how they will be charged from the engine. Catalina and most other builders charged through the main (1/2/both/off) switch but that isn't a great plan for several reasons. The better way is to routs all charging, from any source, to the house bank and charge the start battery with an Echo Charge or ACR. The main switch becomes a control for use, not charging - easier to use and simpler. From the main switch output's common post there are feeds to the starter and to the fuse/breaker panel. The panel feed wire should be able to handle the entire panel's load with 3% voltage drop or less. From the panel the circuits - lights, electronics, etc - are branched off to each.
> 
> On a 27' boat 14 awg is probably a good choice for many circuits. For deciding on wire gauge this link AWG by wire length/amps calculator
> will let you determine the gauge required. The distance is from the source to each load and back. I try for 3% drop or less for everything but lights can tolerate more. The wiring for nav lights and feed to the mast should be 12 awg but it is easy to figure out with the link above. Bilge pump wiring shouls be direct from the battery and not through the main switch. Fuse at the battery for this and fuse the main battery feeds as close to the batteries as possible - ABYC calls for 7" but that isn't always possible.


Sounds good. Got a wiring plan that shows the various panels and buss bars labeled like the maccauley layout?


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## Ajay73 (Jun 13, 2011)

Stu Jackson said:


> Here's one that should answer the basic engine/alternator wiring issues. The PP (previous post) shows the downstream DC wiring quite well. This link includes options as well as a very good wiring diagram from this message board.
> 
> Basic Battery Wiring Diagrams
> 
> ...


Thanks Stu. Appreciate it.


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## mitiempo (Sep 19, 2008)

In the Maccauley diagram I reposted the bilge pump is powered by the lowest fuse in the panel. After a closer look it probably is powered by the 14awg wire direct from the battery, but it isn't that clear. He shows 2 wires crossing, one from a switch that could be going to the voltmeter and then he lists the wire gauge where the wires cross. 

He is also feeding the first panel on the left with a 10awg wire and it then powers the panel on the right with 14awg wire for all loads except the bilge pump. In other words the 10awg is handling everything except the bilge pump. While 10awg can handle 60 amps outside of an engine compartment and 14awg can handle 35 amps outside engine compartments neither are suitable for panel feeds as they are shown in my opinion. This is one of the faults of following someone else's wiring diagram. - you are better off to draw your own and use a wire sizing calc to figure the sizes out. Wire sizing as well as proper fusing (for the wire not the load) is very important. 

Individual circuits are not hard to understand. The book by Charlie Wing suggested earlier is a good choice to help understand and plan your system.

The suggestions by Bill, Stu, and myself for the charging wiring (Echo Charge et all) may be the hardest to plan but the link that Stu posted should help with that.


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## mitiempo (Sep 19, 2008)

Ajay73 said:


> Sounds good. Got a wiring plan that shows the various panels and buss bars labeled like the maccauley layout?


Not one that would apply to your specific boat. You shouldn't copy another boat's system wire by wire - for one it may very well not apply to your boat and for another you will understand your system a lot more if you create a plan for yourself. I think it would be a good idea if after a bit of reading you drew what you think you should and post it here for a critique.

Here is a good example and it does show an Echo Charge wired between the #1 and #2 posts on the main switch. Wire sizes may not apply in your case.


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## eherlihy (Jan 2, 2007)

Maine Sail said:


> Who told you that...? The whole idea of sudden load disconnects is that regulators, no matter how smart, simply can't react fast enough, we're talking microseconds for the damage to be done. In an ideal world a voltage regulator could react fast enough but they very often don't. The Leece-Neville reg on the 8MR's is no different. Even Balmar, Ample, Xantrex or Sterling regs will not protect you if you suddenly disconnect the load while charging..


You're right... I have not tested this, and don't intend to with a $200 alternator.

I should have said that I _believed_ (past tense) this to be the case. (not now)

I read Nigel Calder's and Don Casey's book on electrical systems. The problem is, I don't recall it all that clearly.

Regardless, when I want DC power, I turn the selector switch to position 2, and all is good. If there is a problem, I can turn the switch to position 1, and all _should _be good. NO ONE touches the battery selector switch while the engine is running. Also, there is a clear instruction on the switch NOT to turn the switch to OFF while the engine is running.









I am still considering removing the wire from the alternator to the starter solenoid (it's about 8" long) and adding a wire from the alternator to the #2 post on the battery selector switch, or the battery itself (either way, a run of about 4').

What I can say with absolute certainty - and I hope that the OP will forgive the thread drift - is this;
 the Leece Neville 12v 90A Alternator (at least the one that I received) does NOT require an exciter wire to be run to the key switch. The original alternator did.
When upgrading the Alternator Mounting Bracket on a Universal M25, the Pivot bolt SHOULD BE a Metric M10 fastener, and the tension bolt (connects the tension arm and the alternator) SHOULD BE a Metric M8 coarse thread. The kit that I received from Torrensen, and the kit available from SailboatOwners.Com, include SAE Fasteners.
Both of these factoids would have been very helpful, but were not mentioned anywhere in my research in many online forums and websites (including the Prestolite and Torrensen websites).


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## Stu Jackson (Jul 28, 2001)

mitiempo said:


> Not one that would apply to your specific boat. You shouldn't copy another boat's system wire by wire - for one it may very well not apply to your boat and for another you will understand your system a lot more if you create a plan for yourself. I think it would be a good idea if after a bit of reading you drew what you think you should and post it here for a critique.
> 
> Here is a good example and it does show an Echo Charge wired between the #1 and #2 posts on the main switch. Wire sizes may not apply in your case.


Brian, that diagram has since been updated and has removed the EC from the switch to the banks: Catalina 34 Electrical System Upgrade - C34


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## Stu Jackson (Jul 28, 2001)

eherlihy said:


> Yep Stu, you are right. I am using the 1 B 2 switch to control charging and use.
> 
> 1. I have thought of moving the wire from the C lug to the 2 lug of the battery switch, but the system that I have now is working, and,
> 
> 2. I have the upgraded Leece Neville 90 amp alternator, which also has a semi-smart regulator. If there is no load, it shuts off before the diodes pop.


1. Moving the wire from the C to the 2 post is a very good idea conceptually. I did this for a few years until I installed my new alternator and regulator, BUT I had an unusual arrangement: I had TWO wires from my C post - one to the starter solenoid, another one to the AO. There was no wire between the AO and the solenoid. Why not? Because the PO had those two SEPARATE wires from the C post. Before you switch it, think it through.

2. Maine Sail pretty well covered it, simply not true related to AO.


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## mitiempo (Sep 19, 2008)

Stu

I would wire the Echo between the banks directly as well. It is probably the most appropriate schematic I have to show how it is done - I didn't think one from a 50' twin engine powerboat would help much.


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## Ajay73 (Jun 13, 2011)

mitiempo said:


> Not one that would apply to your specific boat. You shouldn't copy another boat's system wire by wire - for one it may very well not apply to your boat and for another you will understand your system a lot more if you create a plan for yourself. I think it would be a good idea if after a bit of reading you drew what you think you should and post it here for a critique.
> 
> Here is a good example and it does show an Echo Charge wired between the #1 and #2 posts on the main switch. Wire sizes may not apply in your case.


From the reading I've completed the recommendation is that with the battery combiner you don't need a battery switch. You install a separate parallel switch between the two positives from each battery (which each have switches)which allows the batteries to be combined or substituted in an emergency. House and starter circuits are independent. Alternator charges the house battery. My guess is that your amp draws would be much higher than mine so I guess yours wold be overkill for my simple lower amp requirements.


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## mitiempo (Sep 19, 2008)

You do not need the extra starting switch shown in the schematic I posted. You do need either the 1/2/both/off switch shown or alternatively a separate switch for each battery bank. While the combiner (ACR or Echo Charge) will take care of the charging automatically you do need to be able to isolate each battery bank. 

That schematic doesn't show my boat - it is one of many I have on hand, many more complicated.


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## Stu Jackson (Jul 28, 2001)

Ajay73 said:


> From the reading I've completed the recommendation is that with the battery combiner you don't need a battery switch. You install a separate parallel switch between the two positives from each battery (which each have switches)which allows the batteries to be combined or substituted in an emergency. House and starter circuits are independent. Alternator charges the house battery. My guess is that your amp draws would be much higher than mine so I guess yours wold be overkill for my simple lower amp requirements.


You may not be understanding the concept of the 1-2-B switch. Simplicity in itself.

Amp draws have nothing to do with switching concepts, only wire and fuse sizing.

Your "idea" is not new, and was proposed 15 years ago by West Marine. Back then I thought it was nuts and still do. Why replace one simple 1-2-B switch with three switches? Few people have used that idea because of its complexity.

We've kinda given you all the modern thinking on this issue based on your original question. What you choose to do with it is up to you. Your boat, your choice, but I can't think of anything easier to wire, understand and use than Option 1 in my links to you.

The one that Brian showed is Option 2.

You might want to think about it some more.

Good luck.


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## Ajay73 (Jun 13, 2011)

Stu Jackson said:


> You may not be understanding the concept of the 1-2-B switch. Simplicity in itself.
> 
> Amp draws have nothing to do with switching concepts, only wire and fuse sizing.
> 
> ...


"Amp draws have nothing to do". Didn't mean to imply they did-my error. I was just addrerssing mitempo's comment about how each system's amp draws would be different and that I need to develop my own layout and do the math by adding up the loads and determine wire/fuse size. I just tacked that final thought at the end my other comments. Sorry for the confusion.

"Your "idea" is not new". Not my idea. That was from Don Casey's book on page 120 on battery switching. I'll paraphrase him here but he says that with that setup you don't have to make any decisions on switch positions under normal condidions. Just get on the boat and go. And by normal he says house and starter switches are on and the parallel switch is off. I'll quote him directly, "By keeping the starter/starter-battery circuit independent from the house circuit, you never have to change any switch settings while you are aboard. A separate paralleling switch allows the batteries to be combined or substituted in an emergency. The alternator is connected to the house bank. Starting battery charging is accomplished with a battery combiner that connects the batteries when it senses charging voltage". This may not be the latest thinking in your view, or others here, but I just want to understand the componenets of a solid system. My original post did state I wanted up to date thinking but maybe I overemphasized that point. Mostly I want to understand components of a solid, adequately sized, system be that with state of the art components or not so state of the art. Casey's book was copyrighted in 1999 so maybe it's not too far out of date.

Through all this discussion I guess I'm coming to the conclusion that Casey's book maybe my best and less painful path.


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## mitiempo (Sep 19, 2008)

Casey's suggestions are not really out of date but they do have their faults. From the quote above I assume Casey is recommending 3 separate switches - a switch for each bank and a parallel switch. This is over complicated and adds expense where it is not needed. I do agree with Casey's charging of the start battery with a combiner of some type - the Echo Charge is my preference.

You already have a 1/2/both/off switch that will do all you want. House becomes #1, the other battery #2. The scenario that makes the most sense is to treat the start battery as an emergency battery and start on the house bank. When you arrive switch to #1, when you leave switch to off. The other battery is there when needed and always at full charge. 

There is no good reason to ever combine the batteries when starting the engine. If one bank is not able to start switch to the other bank. Combining a good bank with a dead one is not a good plan. The 1/2/both/off switch will allow you to charge both banks in the event that the combiner/Echo Charge fails by switching to the both position.

Casey's idea accomplishes the same result - but it does sell more switches in the process as well as making things more complicated than necessary.


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## Stu Jackson (Jul 28, 2001)

Brian said it better than I did. Everything he said is covered in my earlier links.

The issue is this with three switches: since you don't use them very often to switch battery sources, you will need to write down a scheme for the switching. I would if I had that setup.

You don't need to do that with a 1-2-B switch.

Even I can figure out a 1-2-B switch!

What we're trying to explain to you is how to KISS.



mitiempo said:


> Combining a good bank with a dead one is not a good plan. The 1/2/both/off switch will allow you to charge both banks in the event that the combiner/Echo Charge fails by switching to the both position.
> 
> Casey's idea accomplishes the same result - but it does sell more switches in the process as well as making things more complicated than necessary.


And please note that using B should only be done when charging. This, too, is included in my earlier links.


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## arf145 (Jul 25, 2007)

Ajay73 said:


> If I understand the implication of your 30 year old comment right I'm not looking to reproduce the original wiring plan. I was looking for something more up-to-date. And I'm not looking for something special just for me. What I have are just the very most common of circuits. What I liked about the referenced link was that it was clearer than most of the diagrams I see, written for a layman, so to speak. Most of the discussions about wiring seem confusing to me. But maybe I think it's more complicated than it really is.


Sorry if I misunderstood--I inferred that you were looking for something specific to you and your boat because you stated you already have a diagram you like, yet you were looking for something more. I don't think you can take any wiring diagram and use it as is on your boat. Some pieces will apply, others may need to be different. BTW, I took the advice of many you've heard from here and went with the alternator always charging the house bank with an Echo Charger keeping a back up batt charged. I love the On-Off simplicity of this.


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## eherlihy (Jan 2, 2007)

One more thing - make sure that you *solder all connections* so that they don't vibrate loose.

< runs away quickly >


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## deniseO30 (Nov 27, 2006)

Wow Eh that almost makes me want to re-wire my boat!


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## mitiempo (Sep 19, 2008)

Ajay

Everything you need to know to make good connections that are long lasting and waterproof is here Marine Wire Termination Photo Gallery by Compass Marine at pbase.com

Soldering equipment is not needed.


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## peterm1968 (Sep 26, 2018)

*Re: Catalina 27 wiring*

I'm looking on this diagram and I'm little bit confused. What is other wire color for each of devices (-) - ground, minus, negative?


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## deniseO30 (Nov 27, 2006)

The Marine wiring code has changed over the years.

A simple web search will get you answers use the search words "Marine wiring color code" " wiring symbols"

https://www.jamestowndistributors.com/userportal/document.do?docId=80

https://removeandreplace.com/wp-content/uploads/2016/03/Electrical-Schematic-Symbols.jpg


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