For  installation guidelines and drawings not covered in this Section, please contact Seaguard Ltd.

Three types of reference electrode assemblies are available as standard:

hull_com assem.gif (30420 bytes)
Type A reference electrode assembly. Steel or aluminum electrode body (welded to hull).
Type C reference electrode assembly. Through hull fitting.
hull_com assem_bottom.gif (27597 bytes)

Type A reference electrode

The Type A through hull penetration, illustrated in drawings SG_01_2000 and SG_02_2000 below, is designed as a welded fitting. 

hull_plate6_body_assembly2.gif (11113 bytes) Drawing SG_01_2000

hull_plate6_body_assembly1.gif (14631 bytes) Drawing SG_02_2000

Referring to drawing SG_01_2000, the electrode body will typically be of the same material as the hull. A 50 mm hole is cut in the hull. Welding techniques should followed approved practice with Drawing SG_01_2000 providing an example for hull and electrode body materials of 5083 and 6531 aluminum respectively.

Drawing SG_02_2000 shows the complete fitting. A flexible tube (such as a push lock hydraulic hose) should be attached to the hose tail on the fitting with the end brought above the waterline. This arrangement provides the secondary containment system (the cofferdam) required by some classification societies whilst affording protection to the electrode cable.

Type C reference electrode

As an alternative to the Type B electrode some users may prefer the simplicity of a traditional GRP through hull fitting.This installation involves drilling a single 42mm holein the hull. The fitting is sealed to the hull using a butyl bead or a flexible polyurethane sealant such as 'Bostik Seal N Flex' before the fitting is screwed together.


With any of the above electrodes they should be ideally located on the hull bottom away from the presence of anodes. For a vessel length L, the hull electrode should, ideally, be placed approximately L/3 from the transom. 

Zinc reference electrodes are robust, economical and highly resistant to marine fouling. 

All Sentry units support third party Silver-Silver Chloride electrodes. For each Sentrylog or Sentry multizone fitted the same sensing element type must be used in order to get correct indication.


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