SAMS Vessel Electrical Systems 3

Question 1

During a survey, you discover that a vessel's DC wiring uses automotive-grade wire throughout. The primary deficiency of automotive wire in the marine environment is:

Accepted Answer

Lack of tinned conductors, making it susceptible to corrosion in humid conditions

Answer

Marine-grade wire uses tinned copper conductors to resist corrosion from moisture and salt air; automotive wire uses bare copper that corrodes in the marine environment.

Question 2

Stray current corrosion on a vessel is most effectively detected during a survey by:

Accepted Answer

Using a silver/silver-chloride reference electrode to measure hull potential in the water

Answer

A silver/silver-chloride reference electrode placed in the water adjacent to the vessel measures electrical potential and reveals stray current activity.

Question 3

A vessel's battery bank shows a resting voltage of 12.0V after 24 hours off charge. This indicates the batteries are approximately:

Accepted Answer

At approximately 50% state of charge

Answer

A 12V lead-acid battery at 12.0V resting voltage is typically at approximately 50% state of charge, indicating significant depletion.

Question 4

When evaluating a vessel's AC shore power system, a surveyor finds that the neutral and ground conductors are bonded together at the shore power inlet. This is:

Accepted Answer

A serious deficiency that can cause shock hazard and galvanic corrosion

Answer

Bonding neutral and ground at the shore power inlet on a vessel (rather than only at the source) creates a shock hazard and promotes galvanic corrosion through ground current flow.

Question 5

A vessel is equipped with an isolation transformer for shore power. The primary benefit of this installation for the marine surveyor to note is:

Accepted Answer

It isolates the vessel's AC system from shore ground, eliminating a galvanic corrosion path

Answer

An isolation transformer breaks the galvanic connection between the vessel's underwater metals and shore ground, preventing galvanic corrosion through the shore power cable.

(SAMS) Society of Accredited Marine Surveyors Certified Practice Test

(SAMS) Society of Accredited Marine Surveyors Certified Practice Test

SAMS Vessel Electrical Systems 3