Boat Systems & Maintenance Flashcards

What is the primary purpose of a marine raw-water strainer?

Answer: Filter debris before it reaches the engine cooling system

A raw-water strainer prevents debris, seaweed, and marine growth from clogging the engine's raw-water cooling circuit.

Which type of marine battery is best suited for deep-cycle house bank service?

Answer: AGM deep-cycle battery

AGM deep-cycle batteries tolerate repeated discharge/recharge cycles and are designed for sustained loads rather than high-burst starting.

A technician notices milky-white engine oil on a freshwater-cooled inboard. What is the most likely cause?

Answer: Water intrusion through a failed heat exchanger or head gasket

Milky oil indicates coolant or water mixing with the oil, typically caused by a failed heat exchanger or blown head gasket.

What does a manifold vacuum test on a marine gasoline engine primarily indicate?

Answer: Overall engine health including valve sealing and timing

Manifold vacuum readings reflect combustion efficiency, valve seating, timing accuracy, and cylinder sealing simultaneously.

On a stern-drive unit, what component transfers engine torque to the propeller shaft while allowing steering movement?

Answer: Universal joint (U-joint) assembly

U-joints in the stern-drive allow the drive unit to pivot for steering while continuously transmitting engine torque to the propeller.

Which ABYC standard primarily governs electrical systems on recreational boats?

Answer: ABYC E-11

ABYC E-11 (AC and DC Electrical Systems on Boats) sets the standards for marine electrical installation and wiring.

What is the recommended action when a marine fuel system shows signs of phase-separated ethanol-blended fuel?

Answer: Drain and replace the fuel, then clean the tank and fuel system components

Phase-separated fuel must be discarded because the water-ethanol layer can cause corrosion and lean running; the tank should be cleaned before refilling.