Practice Test Geeks(MST) Marine Service Technician Practice Test
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Boat Systems & Maintenance Flashcards

7 cards from real MST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Boat Systems & Maintenance flashcards as text

  1. A technician finds a marine head (toilet) that won't pump. After confirming the joker valve is good, what is the next component to inspect?

    Answer: The pump piston and cylinder bore for wear or debris

    If the joker valve (check valve) is functional, the next likely cause of a non-pumping manual head is a worn piston, failed O-rings, or debris in the pump cylinder.

  2. What is the ABYC-recommended minimum wire gauge for a DC circuit carrying 20 amperes over a 15-foot run (30-foot total circuit length) with a 3% voltage drop limit on a 12V system?

    Answer: 14 AWG

    Using the ABYC ampacity and voltage drop tables, a 20A circuit with a 30-foot total conductor length on 12V with 3% drop requires 14 AWG minimum.

  3. Which symptom most strongly indicates cavitation in a marine propeller installation?

    Answer: Rapid RPM fluctuation accompanied by vibration and reduced thrust

    Cavitation causes vapor bubble collapse on the blade surface, producing RPM fluctuation, vibration, and reduced thrust rather than simple over-revving.

  4. When a marine alternator charges at a low voltage (below 13.5V) with the engine at operating RPM, what is the first component to test?

    Answer: Alternator belt tension and condition

    A slipping or loose alternator belt is the most common and simplest cause of undercharging before investigating the regulator or alternator internals.

  5. What is the purpose of the expansion tank in a closed freshwater cooling system on a marine inboard engine?

    Answer: Store reserve coolant and accommodate thermal expansion without pressurizing the system excessively

    The expansion tank provides a reservoir for coolant volume changes as it heats and cools, maintaining system pressure within design limits.

  6. A technician is diagnosing an outboard that starts and idles well but hesitates when accelerating from idle. Which carburetor circuit is most suspect?

    Answer: Accelerator pump circuit

    The accelerator pump provides a momentary shot of fuel when the throttle is opened quickly, bridging the lag between idle and main jet circuits.

  7. According to ABYC standards, what is the maximum allowable AC voltage drop on a shore power cord and inlet connection under full rated load?

    Answer: 3% of supply voltage

    ABYC E-11 limits shore power conductor voltage drop to 3% or less to protect onboard equipment from undervoltage damage.