The smaller air base
Building the Navy’s Bases in World War II says a smaller air base was known as an ACORN. The major air base was an OAK. These were shore assemblies of men and material. An ACORN is not a hull.
The Seabee Museum article puts an ACORN at about one-fourth of an OAK. That is the article’s proportion. The July 1942 directive, below, defined an OAK as four airfield units, which is the same proportion.
July and August 1942
The Logistics of Advance Bases quotes a directive of 4 July 1942. Land-based aircraft needed fields. The assemblies were to build and run mutually supporting island air bases, and, with an amphibious operation, to repair and run a captured airfield. The directive asked for seven groups. Each group was one portable carrier deck and three airfield assemblies. Each airfield assembly was two runway strips of metal mesh or perforated plate, construction equipment, gear to rearm, refuel, and service planes, and containers for aviation gasoline and lubricants. The personnel asked for, with each material group, were a commanding officer, two construction battalions, four communications groups, a small base service unit, and two groups of aviation ground personnel. Each of those ground groups was to service one carrier group and twelve patrol bombers or transports. Each airfield was to service one carrier group.
The same directive gave the names. OAK No. 1 through 7 was a group of four airfield units. ACORN No. 1 through 21 was a component of those groups. In each OAK the lowest numbered ACORN was the carrier-deck unit. The first three OAKs were to be assembled at the West Coast depots at Port Hueneme and Oakland.
A second directive, 18 August 1942, called landing-strip ACORNs Red and carrier-deck ACORNs Blue. The first eight to ship were all Red. The base unit in that plan totalled 38 officers and 1,180 enlisted men, most of them with the construction battalion. The history says the ACORN, rather than the OAK, was made the basic unit so it could be moved.
The December 1942 trial
That autumn a separate project, Goldrush, studied a still more mobile ACORN, called Gold or Silver in the history. The aim was one runway for a carrier group, put ashore quickly. The study named six LSTs and six LCIs for the landing. A trial was run near Norfolk from 1 to 8 December 1942, and a report was issued on 17 December. On 20 December, Op-30 directed that ACORNs after No. 6 follow that layout. Training was set up at Port Hueneme. Commander M. B. Gurney was detailed as commanding officer of the ACORN Training Detachment.