Definition

Noun 1. A supplementary boiler on a ship: An auxiliary boiler is an extra steam-generating unit installed on a vessel, typically used when the main boilers are not in operation, such as when the ship is docked in port.

Usage

• The term is primarily used in nautical and marine engineering contexts to refer to a secondary source of steam power on a ship.
• It is a compound noun where "auxiliary" modifies "boiler" to specify its supportive or backup function.

Examples

Advanced Usage

• "Fired" vs. "Unfired" Auxiliary Boiler: In technical specifications, an auxiliary boiler may be described as "fired" (using fuel) or, in some modern contexts, could utilize waste heat, though this is less common for the traditional definition.
• Operational Context: Its use is often associated with specific operational modes: "in-port operations," "cold iron" (ship with main engines shut down), or "emergency standby."

Variants and Related Words

• Donkey boiler: A historical synonym for an auxiliary boiler, especially on steamships.
• Auxiliary machinery: A broader term for all supplementary mechanical equipment on a ship, which may include the auxiliary boiler.
• Main boiler: The primary boiler(s) used for propulsion at sea.

Synonyms

• Supplementary boiler
• Backup boiler
• Donkey boiler (historical/nautical)

Related Phrases

• Port boiler: Informal term emphasizing its use while the ship is in port.
• Auxiliary steam supply: The function provided by the auxiliary boiler.

Noun

1. (nautical) an extra boiler (as a ship's boiler that is used while the ship is in port)