Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

Many technicians prefer to use a common

zinc electrode as a reference cell, and zinc will

work. However, I prefer to use a silver/silver

chloride cell because ABYC Standard E-2,

Cathodic Protection, bases all its voltage

potential values on the silver/silver chloride

cell (see the table on page 106). If you choose

to use a different reference electrode, the stan-

dard does provide conversion tables. In the

case of zinc, you would add 1 volt to your

meter reading to convert to the values in

104 electrical systems troubleshooting

Standard E-2. Personally, I find this all rather

confusing and prefer not to deal with conver-

sions in a working situation.

Underwater Metal Corrosion and Protection Basics

A basic corrosion survey tests the electrical

potential of your boat’s hull (the metal) to

answer two questions:

DVOM

connecting

lead

silver/silver chloride

reference electrode

A conventional DVOM and a silver/silver chloride reference electrode. This one is made by USFilter (now

called Siemens Water Technologies) under the trade name Capac, but the cells are readily available

through Mercury engine special tools catalogs or West Marine. The electrodes cost about $85. The Capac

unit costs about $250 and is equipped with an extremely long connecting lead for use on larger boats.

Capac, Siemens Water Technologies, http://www.usfilter.com

Model 20008, ProMariner, http://www.promariner.com

SILVER/SILVER CHLORIDE REFERENCE ELECTRODES