Idaho was the third of the New Mexico class battleships, commissioned in 1917-1919. All three were modernized in the 1930's, receiving "tower" superstructures of a unique design, instead of the more conventional tripod masts. During WWII the ships never underwent a major modernization, but did receive modest refits and improved anti-aircraft armament. Idaho received a unique intermediate armament of 10 destroyer-type 5-inch/38-caliber guns in single turrets alongside the superstructure, replacing her previous 5"/51cal and 5"/25cal batteries. Although a similar outfit was planned for her sisters, they instead received other AA outfits, leaving Idaho in the unique configuration seen here.

ABSD 3 was one of seven Advance Base Sectional Docks built during WWII to support the Fleet in the Pacific. These docks were constructed in ship-like sections which could be towed, with the sidewalls folded flat on deck, to any convenient fleet anchorage. After arrival at the forward base, the sidewalls would be raised and the dock sections assembled to form a large, self-sufficient floating drydock. ABSD 1 through ABSD 3 were built as 10-section docks, with a nominal lift capacity of 100,000 tons. However, ABSD 3 was ultimately assembled in a nine-section configuration, as seen here. ABSD 3's 10th section was reassigned to ABSD 2, replacing a section that had been reassigned to ABSD 1 after one section of that dock was sunk during assembly at a Pacific base. This left ABSD 3 as the sole nine-section drydock.

ABSD 3 saw brief, but very busy service during WWII, and went into reserve postwar. After over 30 years in reserve, the dock was transferred to the state of Maine in 1981, leased to Bath Iron Works, and placed in service at Portland, Maine. After nearly 20 years supporting BIW's cruiser and destroyer construction programs, and various overhauls and repairs, the dock was only recently replaced by a new drydock. The former ABSD 3, now nearly 60 years old, has been sold to a Croatian shipyard and will be transported to Europe on a heavy-lift deckship.

Correct answers were received from: James T. Flynn, Jr., Mike Potter, Bill Ullmann, Bill Vickrey, Mark Karolus, Jeff Smith, Maurizio Brescia, Czéh György, Merlin Dorfman.