Rewiring a boat - wire gauge

Started by Gobi King, July 10, 2020, 11:56:30 AM

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Gobi King

Lee and others who have knowledge of boat wiring - could you please list the wire/gauge you use most

for a boat that is 20 ft in length

Power from batt to engine
Power from batt to anchor
Power to helm electronics
Helm to lights and other gadgets
Shibs - aka The Gobi King
Fichigan

Keta

#1
Power from batt to enginn

Inboard or I/O?

Power from batt to anchor

Anchor winch?  What is the amp load and total length from battery or battery selector switch?  If it is a anchor winch it will be one of the highest loads on the boat, I like to put a battery in the bow closer to the winch so I can run smaller wire to it but it will still be large wire. If new the wire size should be in the install manual.  A guess would be a minimum of 2/0.

Power to helm electronics

I usually use 10 gave but it depends on total amp load plus rooms for additional electronics and accessory's.

Helm to lights and other gadgets

14ga or 16ga have for most lights, I would go at least 14ga for windshield wiper motors but depending on amp draw I would go up to 12ga.

I am converting to LED lights on the project boat, I run a side operation for the owner of a LED light supplier, and can use much smaller wire but will run 16ga.  I have a large screen Garmin chart plotter and a Lowrance DHS7 gen3 with a gen3 radar to install so my load there will be higher, I plan on using 10ga but need to add up the load and length of run before I buy the wire.  
Hi, my name is Lee and I have a fishing gear problem.

I have all of the answers, yup, no, maybe.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Crow

https://www.12volt-travel.com/knowledgebase/wire-size-guide-chart/

My advice is " bigger is better" , when it comes to wiring....if 14 gauge is called for....I use 12. For any 'main feeds', add up the total requirements for ALL things that use power , and use that amperage number...even if all that stuff won't be used at the same time. It will save you headaches, down the road. Use breakers, or fuses, on everything, secure all wires so they can't chafe , and use a 'loom". They make wire in almost every color...so either use different colors for different uses, or use wire tags...makes tracing stuff WAY easier.
There's nothing wrong with a few "F's" on your record....Food, Fun, Flowers, Fishing, Friends, and Fun....to name just a few !

Keta

#3
I tend to run one size up too.  On the harvesters I am wireing I have both AC and DC circuts all DC is wired to marine code for colors so I do not mix up a black AC hot wire with a black DC ground wire.

I have several marine breakers up to 100 amp I will be using, a 100a to the forwarded fuse panel. Imight need to buy a 150a one for the motor but have not looked into it yet. I detest inline fuses but they are a low cost alternative. I have a Bluesea Systems 12 circuit fuse panel with a ground buss.  I also have a Bluesea Systems ACR that will go between the batteries and a BSS battery shut off/selector switch to install.

https://www.jamestowndistributors.com/userportal/document.do?docId=80
Hi, my name is Lee and I have a fishing gear problem.

I have all of the answers, yup, no, maybe.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Gobi King

Gentlemen,
Thanks, gotcha one size up, given the length of the run and amps, 10 g looks like is the ticket.

Yes, I read some Hummingbird guys having voltage issues with factory 12g runs to the helm and had to run a separate 10g run to the fish finder to get more voltage.

Dang, that is a lot of colors, my boat has an outboard (90hp merc) but I am thinking ahead and I want to pick up a used coast guard vessel someday.

I like the bus idea but I need to figure out how to make use of the switched power trigger from the helm
Shibs - aka The Gobi King
Fichigan

Keta

When pulling wire pull another pull rope for future wires and run a spare hot and ground.

I had to pull foam floatation out if the project boat to reach wire ties when pulling the old steering cable so I have good access, I will not secure anything under the foam when I put it back.
Hi, my name is Lee and I have a fishing gear problem.

I have all of the answers, yup, no, maybe.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Keta

#6
My fuse panel w/ground buss, ignore loose wires they will be secured.



Garmin network box, onboard charger and NEMA 2000 network cables, wires look like #### but will be secured.



The ACR I am installing.



Something is missing????



Hi, my name is Lee and I have a fishing gear problem.

I have all of the answers, yup, no, maybe.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Stan

Here is a pretty good link for determining wire size for a particular run.

https://www.bluesea.com/resources/1437

Gobi King

Lee, thanks for the pics, what is the draw of the ACR when it is sitting?

I opted to use a minnkota alternator charger (not sure if it has a draw when the boat is off) to charge my trolling motors.

striper, I have 12g wire from batter to my helm where I have a hummingbird Onix 10, the length is well under the "calculated run" but the connection are crappy and I have some voltage drop at the connection, boat has a crestliner wiring harness from batt/motor to helm.

Looking at the price of wire by foot, it is much cheaper to buy the entire roll of wire.
I am going for:
10g - Red and Black
2g - Red and black


Shibs - aka The Gobi King
Fichigan

Keta

#9
Zero, it only combines batteries when charging.

https://www.bluesea.com/resources/1366



I got the new motor installed today.

Hi, my name is Lee and I have a fishing gear problem.

I have all of the answers, yup, no, maybe.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Gobi King

Looking good, what prop are you putting on that shiny motor?

I did some googling, ACR has 15mA to 20mA draw on standby,

I bet my Minnkota Alternator Charger has a draw too on standby unless they wired it to the master kill switch.

How do I go about checking if my minnkota draws current on standby?
Shibs - aka The Gobi King
Fichigan

Keta

Hi, my name is Lee and I have a fishing gear problem.

I have all of the answers, yup, no, maybe.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Alan Matsuno

I used to have a book: 12 volt bible for boats.

I used it when I wired my boat.

Gobi King

I really like the idea of pulling a spare Power and ground line, in my boat I have to take panels off and the soft aluminum body makes it difficult, one has to be really careful align screws with existing hole before going crazy with power driver (ask how I know).



I am going to add a tripping fuse that I can reset at the main power hub.
Shibs - aka The Gobi King
Fichigan

milne

Wiring is an interesting exercise.
Being 1/2 way thru mine at the minute, what I have figured out, is you need to work out the draw on each circuit, to figure the gauge.
I've gone over the top, to keep it simple and not have to buy 10 different gauges.
The thing I found interesting and what should be taken seriously, is voltage drop over long runs.
What I have done to reduce gauge thickness in some instances, is install relays on long runs, for my bilge pump and deck wash for instance.
With the bilge pump recommended gauge thickness specified from the manufacturer, over a 4 meter long run, I had voltage loss, it would have been 10.5 volts at the pump at that length of run. Can the bilge pump run with only 10.5 volts, the specs say it can,,, but simply installing a voltage regulator close to the appliance, then direct to a battery buzz bar down back, this eliminates voltage drop and delivers the full 12 volt at the pump.
Just some things to consider when working out wire gauges,,, fires are horrible on land, but devastatingly more scary at sea...

Col