ABYC Color Code Standards

Modern boats are have complex systems that often span great distances. Wires travel in hidden compartments often bundled with many other wires. These challenges make tracing a wire on a boat a serious task.
The use of the A.B.Y.C. Color Code Standards attempts to help wire identification simple. The American Boat and Yacht Council system is a standard used by most boat builders. Knowing these color standards makes troubleshooting electrical systems more efficient. 

How it works.

On Boats, specific color wire get used in specific systems. For example, Pink Wire is for a Fuel Gauge Sender to Gauge. 

Black BK 0 Ground Negative / Neutral Main Return
Brown BR -1 Alternator Charge Light
Generator Armature
Generator Terminal or Alternator Auxilliary Terminal to
Generator Armature to Regulator
Circuit Breaker or Switch to Pumps
Red RD -2 Instrument Feed
Power Feeds
Distribution Panel to Electrical Instruments
Positive Main Power (particularly un-fused)
Orange OR -3 Accessory Feed
Common Feed
Ammeter to Alternator or Generator
Distribution Panel to Accessory Switch
Accessory Circuit Breakers or Switches
Yellow YL -4 Generator Field
Generator to Regulator Field Terminal
Negative / Neutral Main Return
Green GN -5 Bonding System Grounding Wires (if insulated)
Lt. Green LG -15 N/A N/A
Blue BL -6 Cabin & Instrument
Fuse or Switch to Lights
Lt. Blue LB -16 Oil Pressure Oil Pressure to Sender to Gauge
Violet VI -7 Ignition
Instrument Feed
Ignition Switch to Coil & Electrical Instrument
Distribution Panel Electrical Instruments
Grey GY -8 Navigation Lights
Circuit Breaker or Switch to Lights
Tachometer Sender to Gauge
White WH -9  N/A  N/A
Tan TN -11 Water Temperature Water Temperature Sender to Gauge
Pink PK -12 Fuel Gauge Fuel Gauge Sender to Gauge