Terms To Know: Shakedown and Overhaul

Reading through military history is likely to bring up a few unfamiliar words and phrases. For instance, what does it mean when a vessel undergoes a “shakedown cruise” or an “overhaul”? Understanding terms like these helps to expand your knowledge about naval operations, which will come in handy as you read up on some of the iconic ships of Pearl Harbor like USS Arizona, USS Missouri, and USS Oklahoma.

“Shakedown” and “overhaul” are terms that frequently come up while reading about a ship’s history. Since it’s one of the first things that a new ship goes through, we’re going to start with “shakedown,” which might sound like something unsavory but it really isn't.

What is a Shakedown Cruise?

USS Arizona leaving New York for her shakedown cruise

The first step in building any new ship is when its keel is laid down in a dock. Construction continues in a dry environment, which means that before it’s sent off into service, it must undergo open water testing. When USS Arizona (BB-39) was commissioned into the US Navy in October of 1916, her first order was a shakedown cruise.

During a shakedown cruise, the new ship is put through simulations of real life working conditions. This allows the crew the opportunity to get familiar with the ship and to ensure the vessel is fully functional. In the case of Arizona, the shakedown led to the discovery of a stripped turbine, which forced her to return to New York for repairs. Coincidentally, the stripped turbine was discovered on December 7, 1916, exactly 25 years before Arizona was sunk when the Japanese attacked Pearl Harbor.

The term “shakedown cruise” is believed to have originated during the transition from sail to steam power. The early engines would cause vibrations throughout the ship’s hull and, during maiden voyages, it wasn’t uncommon for fittings and fixtures to come loose and fall to the deck, or “shake down.” Before vessels were better designed for powered propulsion, “shake down” crews were sent with the ship on maiden voyages to make necessary repairs.

What is an Overhaul?

Not specific to naval terminology, an overhaul means the pretty much the same thing in most fields. When a ship returns to port for an overhaul, it’s being placed in maintenance mode to repair damage, replace current fixtures, or undergo modernization.

When it comes to the ships of the US Navy, overhaul often refers to the outfitting of new weaponry. In 1919, three years after being commissioned into service, USS Arizona underwent an overhaul to remove six 5” guns and modernize the fire control system.

USS Pennsylvania (BB-38) in dry dock for overhaul, 1944

Even in the thick of war, improvements are made to vessels of the fleet, and it wasn’t uncommon for a ship of the Pacific Fleet to be ordered back to port for an overhaul. For instance, Arizona's sister-ship USS Pennsylvania (BB-38) was ordered to San Francisco after taking part in the Battle of Midway for a week-long overhaul.

In many cases, an overhaul simply meant undergoing repairs, as Pennsylvania did in May through June of 1943, after taking part in the bombardments of Holtz Bay in the Aleutians.

There is plenty of terminology to learn if you want to really immerse yourself in nautical speak, and “shakedown” and “overhaul” are a good start, especially since every ship of the Pacific Fleet, including those at Pearl Harbor, underwent both at various points in their lives.