Saturday, February 9, 2013


Application: iPhone, iPad, iPod Touch iOS 5.0
Function: Electrical Wire sizer
Rating: ***
Cost: $0.99

Yachts today are becoming increasingly more complex with the many electronics and systems on board.  Even with all these bells an whistles, there may come a time when you want to add additional equipment.  You may want to add a chartplotter to help you navigate, an VHF radio to communicate, a stereo to help you gyrate or a AIS transponder to keep track of other vessels around you.

If your a "do it your selfer" like me you may want to take on installing some of this equipment your self.  It is not hard to do if you know a few basics.  There are plenty of resources on the internet these days. When in doubt, Google it to find thousands of links to help you out.  YouTube is full of self help and how to videos on just about any subject.  Or, how about an app to help you with your boat wiring project?

Wiresizer is a great little app to help you with some basic electrical installations. It is a must have for your electrical toolbox.  By selecting a few parameters it will provide you with the right size wire for the job. 

Once you have opened the app, select the settings icon in the upper right side of the screen. Here you can set the parameters for measurements and wire sizes.

When you are adding wiring for a new circuit for electrical equipment there are a few things you must consider.  The app takes these into account so all you have to do is select the proper values.   The values can be easily selected by spinning the rollers to the correct value.

First enter the voltage of the circuit. If your working on your boat it will most likely be 12 volts. 

Next, select the current that will be needed to serve the new piece of equipment.  Most equipment will have a power rating in watts. Using the P = VxI formula, where P = watts, V = voltage and I = current we can solve for I = P/V

The last piece of data to enter is the length of the circuit.  This is the distance from your boats breaker panel to and from the new piece of equipment. Use the total round trip distance.

Once all the top settings are selected the app automatically calculates the Minimum Wire Gauge in the bottom section . Various percentages of voltage drops are listed here.

ABYC suggest a 3% voltage drop for critical circuits like electronics and up to 10% voltage drop for non critical circuits like lighting.

If you are going to do any serious wiring on your yacht consider getting a copy of the ABYC electrical standards.  These are the standards used by the marine industry for electrical and other system on your yacht. 

There is a selection at the bottom to determine if the wiring will be inside the engine compartment. The rating will be affected by the added heat from the engine.

Selecting the proper wire size is crucial in safely serving the equipment and preventing overloaded circuits and possible fire.


Yellow w/red stripe (YR) Starting circuit Starting switch to solenoid
Brown/yellow stripe (BY) or
Yellow (Y) - see note
Bilge blowers Fuse or switch to blowers
Dark gray (Gy) Navigation lights
Fuse or switch to lights
Tachometer sender to gauge
Brown (Br) Generator armature
Alternator charge light
Generator armature to regulator
Auxiliary terminal to light to regulator
Fuse or switch to pumps
Orange (O) Accessory feed Ammeter to alternator or generator output and accessory fuses or switches.
Distribution panel to accessory switch
Purple (Pu) Ignition
Instrument feed
Ignition switch to coil and electrical instruments.
Distribution panel to electric instruments
Dark blue Cabin and instrument lights Fuse or switch to lights
Light blue (Lt Bl) Oil pressure Oil pressure sender to gauge
Tan Water temperature Water temperature sender to gauge
Pink (Pk) Fuel gauge Fuel gauge sender to gauge
Green/stripe (G/x)
(Except G/Y)
Tilt down and/or trim in
Tilt and/or trim circuits
Tilt and/or trim circuits
Blue/stripe (Bl/x) Tilt up and/or trim out
Tilt and/or trim circuits
Tilt and/or trim circuits

The table above is the standard color coding system for marine wiring.  Follow these wire colors to make your project look factory.  Make sure to use only stranded and tinned wire in your marine wiring projects.  Marine wire is specially made to prevent corrosion and stand up to the tough marine environment.

Good luck with your next project!

~~~Sail On~~~ /)


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