MTC Steering & Propulsion Systems Flashcards

What is the most common cause of excessive play (looseness) in a mechanical boat steering system?

Answer: Worn or stretched steering cable or loose helm connections

Steering cables stretch and wear over time, and loose connections at the helm or tiller arm create play that reduces steering precision and control.

When bleeding a hydraulic steering system on a marine vessel, what is the correct procedure?

Answer: Attach a vacuum pump to the fill port while turning the wheel lock-to-lock

Using a vacuum pump at the fill port while cycling the steering wheel lock-to-lock draws air bubbles out of the system and allows clean fluid to fill all passages.

What does 'propeller cavitation' mean in the context of marine propulsion?

Answer: Formation and collapse of vapor bubbles on propeller blades causing pitting and loss of thrust

Cavitation occurs when low pressure on the propeller blade face causes water to vaporize; when these bubbles collapse, they create micro-jets that erode the blade surface and reduce efficiency.

What is the purpose of a trim tab on an outboard motor or sterndrive?

Answer: To control the running angle of the vessel to optimize performance and fuel efficiency

Trim tabs (on the cavitation plate or transom) adjust the bow-up or bow-down attitude of the vessel, allowing the hull to run at its most efficient planing angle.

When inspecting a propeller shaft for runout, what tool does a marine technician use?

Answer: Dial indicator (dial gauge)

A dial indicator measures the total indicator runout (TIR) of the shaft as it is rotated, revealing bends or eccentricity that would cause vibration and bearing wear.

What is the function of a cutlass bearing in a marine propulsion system?

Answer: To support the propeller shaft and allow it to rotate smoothly

The cutlass bearing is a water-lubricated rubber bearing that supports the propeller shaft inside the strut or shaft log, reducing vibration and preventing metal-to-metal contact.