Alabama Boaters Engine Basics 2

Question 1

What does the term 'cavitation' refer to in a boat engine system?

Accepted Answer

Formation and collapse of vapor bubbles around the propeller

Answer

Cavitation occurs when low-pressure areas around the propeller cause water to vaporize, forming bubbles that collapse and can damage the propeller.

Question 2

Which type of cooling system circulates raw water directly from the lake or river through the engine?

Accepted Answer

Open (raw water) cooling system

Answer

An open raw-water cooling system draws water from the surrounding body of water directly through the engine and expels it with the exhaust.

Question 3

Before starting an inboard gasoline engine, you should run the blower for at least how long?

Accepted Answer

4 minutes

Answer

Running the blower for at least four minutes before starting an inboard engine ventilates the bilge and reduces the risk of gasoline vapor explosion.

Question 4

What is the primary purpose of a boat's thermostat in the cooling system?

Accepted Answer

Maintain engine operating temperature

Answer

The thermostat regulates coolant flow to keep the engine within its optimal operating temperature range.

Question 5

What does a 'four-stroke' engine complete in two crankshaft revolutions?

Accepted Answer

One complete power cycle (intake, compression, power, exhaust)

Answer

A four-stroke engine completes one full power cycle—intake, compression, power, and exhaust—in two full crankshaft revolutions.

(Alabama Boaters) Alabama Boaters Certification Practice Test