Wiring gauge Question

I am restoring a 1988 21' Starcraft Mariner CC with a 90 hp Evinrude. I was wondering what gauge marine wire I should use for most of the wiring. I know the battery wires are large but all the others I'm guessing are 14 gauge ? Any help or tips would be greatly appreciated.
Thanks
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Welcome to the Forum.
For the US it is codified in 33 CRF Chapt 1, Subchapter S, Part 183 section 183.425 Federal Register :: Request Access https://www.ecfr.gov/current/title-33/section-183.425
Actually reading all of 33 CRF Chapt 1, Subchapter S, Part 183 would be helpful. Federal Register :: Request Access https://www.ecfr.gov/current/title-33/chapter-I/subchapter-S/part-183

 

Hard to understand

 

See my replies on BBC. Fire is a major risk to boats, so while good to see you redoing the wiring; it must be done well. Just the crimping tool for wires about size 8 and up is pretty expensive. I think I paid $150 for my crimper.

Minimim wire for boats is 16 gauge; excepting device pigtails.

I used a little 14 gauge in my build when ampacity limits for 16 gauge were close.

 

So what do you recommend 14 gauge ? I also plan on soldering all my connections and shrink tubing same.

 

this depends entirely on how much load the wire will take and over what lengths. An LED running light requires a whole lot less than a 2000 GPH bilge pump.

 

all depends on ampacity demand of the circuitry

a 20 amp fuse panel with anticipated loads of 12 total amps max 15 feet from the battery is 30 feet of circuit..using 10% voltage drop max is 12 gauge wire, 3% chart is 8 gauge

You cannot generalize all the wiring in a boat. You will need 16 gauge to wire most small lights, etc. For all larger items, you need to know the load. A trolling motor, for example might require 6 gauge wiring..or 4, etc.

 

Per ABYC; (paraphrasing,) "Solder shall not be used as the sole connection for wiring".
Get a good crimping tool, use tinned marine grade wire, use tinned marine grade crimp fittings.
DO NOT use solder on the main connection to the starter.

 

Good catch rb, I missed that. Solder is not done. Had some bozo early on tell me how to solder things.

You can buy an inexpensive hammer type crimp for large connections.

A good small crimper is essential. Here is one that will save you tons of headaches.

Ancor Wire Cut, Strip and Crimp Tools https://www.amazon.com/dp/B00T59KW1O/ref=cm_sw_r_cp_api_i_38MNV9BRBFCPTXZDY1BB

Here is a cheap solution to crimping heavier wire. Not tested by me. I paid like $150 for mine.

E-Z Red B790C HAMMER INDENT CRIMPER | Tool Discounter https://www.tooldiscounter.com/product/e-z-red-hammer-indent-crimper-ezrb790c?msclkid=aa489733a9fa1c452899f5a67ba1c555

Here is mine for a small yacht job. This one is really quality tool, but I was not glad about the $$. I spent a little extra because I had soldered a couple non-starter related connections and this thing doesn't care.

TEMCo TH0020 Lug Crimper Tool for 10 AWG - 400 MCM wire lugs- DIELESS Indent Electrical Battery Terminal Cable Wire https://www.amazon.com/dp/B00HJYY5GA/ref=cm_sw_r_cp_api_i_MMAK7E1B4KZHHY5BANMA

 

Google. Bluesea.com
Choosing wire conductors
There is a chart that shows wire gauge recommendation based on length of run and current demand
ABYC has one as well but I am unable to access the link at this time
Rangebowdrie mentioned tinned marine wire.
I have not run across tinned crimp terminals as I think that the barrel in most terminals are aluminum but perhaps some one will clarify
The insulated terminals that I use have the shrink insulation on the barrel. Crimp the fitting, heat the insulation and it shrinks
on the wire to form a seal
If I am making a joint up where there will be moisture present and an imperative joint, ie bilge pump, I apply a coating of
Liquid Tape, which is a ultra fast drying rubber sealant on the joint
Maybe $8 a can from NAPA
When making up a heavy battery cable, using brass terminals, which are normally not insulated, they also get application of Liquid
Tape
If you have factory style plug ins, ie the small multi pin connectors, I apply a coating of DowCorning DC 4 dielectric grease to keep moisture out
Dupont bought this out from Dow but it is referenced online. Not cheap seems like it lasts forever. I have tubes over 15 years old.

 

All the connectors I have been buying are tinned copper. This is a crosscut of a small gauge butt connector; got plenty more than I'll ever use.

 

How to calculate wire size Boat Building Regulations | Boat Electrical Systems | Wire Size | New Boatbuilders Home Page https://newboatbuilders.com/pages/elect3.html

Neither ABYC or the USCG prohibit solder, it can be used but (and that's a big but) it can not be the sole means of support, and it creates a hard spot in the wire that is not flexible, therefore more susceptible to breaking. The best method is crimping with a really good crimper. Do not scrimp on this tool. Get the best you can afford. Also liberal use of dialectric grease at fittings is really good practice. It seals out moisture. On my boat (a 1972 Sea Ray SRV 190 (i8 ft) I/O I replaced most of the wiring. The smallest 16 ga. If there is a doubt go up a gauge to 14. There are lots of charts on the net but the best is to just do the calculation yourself based on amperage, length of wire, and voltage drop.