What is the most common type of blower found on Coast Guard engines?

• A. Roots Blower
• B. Blower (Also supercharger)
• C. Air Cleaner
• D. Air Silencer

Answer: (A)

The concept tested is how air is delivered to the engine for scavenging in two-stroke marine diesels. A Roots blower is a positive-displacement device that pushes a fixed volume of air into the cylinders during the scavenging stroke, providing reliable, steady air delivery at the engine speeds typical on Coast Guard vessels. This makes it the most common choice for these engines.

Air cleaner and air silencer aren’t blowers at all—they handle air intake filtration and exhaust noise reduction, respectively. The generic term “blower” is too broad; the Roots blower is the specific, commonly used type that fits Coast Guard engine setups.