Electronics - Marine and Boat Repair Salisbury MDAt Ellison Marine, we provide a ll electrical repairs and installations for your vessel. Contact us today to get your radar, radio, CD/DVD or any other electrical device installed or replaced.

Some Wiring Basics

Standard colors for boats since 1980 are as follows ,

  • heavy red 10 gauge (main battery)
  • heavy black (main ground)
  • purple (ignition)
  • yellow (starter solenoid)
  • grey (tachometer)
  • brown (temperature)
  • blue (oil pressure)
  • brown with stripe (alarm)


  • pink (fuel sending unit)
  • yellow (blower)
  • brown (bilge pump)
  • grey (navigation lights)
  • heavy green (bonding wire)
  • red (misc electrical ad ons , vhf , depth finder, stereo, radar, power supplies)

Common Problems

  • Check to see that the acid (electrolyte) level is up to the plastic liner inside holes and the fully charged specific gravity is 1.25 to 1.30 in each cell . (A tester can be purchased for less than $6.00)
  • Be sure that the top surfaces stay clean and dry or they will slowly discharge the batteries.
  • Check that all connections are tight with a pair of pliers or wrench, finger tight is not good!
  • Check to see if the engine cranks properly for 10 seconds with each battery alone, ground the ignition coil wire to a safe place and check for any gas fumes prior to checking, then crank the engine over so it won’t start but only turn over.
  • Check that all the cables are in good condition and the connections are clean and sealed from moisture.
  • Fasten all batteries down really good , they can cause a major disaster if they come loose in bad sea condition, fire can result.
  • Replace any batteries over 4 years old , it only leads to trouble.

Wiring & Connections

  • Check all battery switch connections to make sure there is no corrosion building up behind the switch.
  • Make sure all fuses have clean, tight, sealed contacts , use electrical tape sealer on all connections and replace connectors before they cause you problems.

Alternator & Starters

  • Check that with the with engine running and the batteries fully charged, and a 1 or 2 Amp load on system (a bilge pump or blower turned on), voltage to batteries is 13.9 to 14.4
  • Volts — and the voltage remains constant as more loads are turned on.
  • Make sure external connections are clean, sealed from moisture, and positive terminals are covered and alternator drive belt(s) are tight and in good shape no cracks or frays.
  • Listen for any strange bearing noises that might indicate upcoming problems from the alternator.
  • Watch for any signs of leaking water coming from exhaust manifolds and risers which are usually the number one cause of the starter solenoid being corroded and malfunctioning.
  • Keep the bildge dry from any water supply , this is the number one reason why all starters are replaced.


  • Check that if the engine cooling system uses internal zinc protection that the zincs are not corroded away.
  • Don’t leave batteries chargers on 24 hours a day 7 days a week , this only leads to trouble, if you have a built in charger , it’s only for convenience, use it if you haven’t been on the boat for a few weeks .
  • Checking for battery drain, disconnect positive terminal and lightly rub up against battery terminal ans see if you get a very slight, small spark , if so then something is draining the battery , check all cabin lights etc.

Electrolisis ~~~~~~~~ Stray Current (an explanation)

Stray current is electricity that is flowing where it’s not supposed to – through water, fittings on your boat, wet wood, damp surfaces, etc. It can be a shock hazard and it can cause corrosion (technically known as electrolytic corrosion).

Stray current corrosion is caused by a power source such as your batteries or the shore power connection. It is unlikely for serious corrosion to be caused by stray currents flowing through the water, without a metallic path to your boat. Because of the relatively high driving voltages, stray current corrosion can act far more quickly than the corrosion caused by dissimilar metals in contact (galvanic corrosion).

Note: The word electrolysis is often mistakenly used to describe various kinds of corrosion. Electrolysis actually refers to the bubbling off of gases that occurs with electrolytic corrosion.