Tiny Seaplane Tenders
By Mike Bennighof, PhD
January 2008

During the 1930's, both Japan and the United States looked to the seaplane as a vital component of their Pacific war plans. Naval limitations treaties, as well as expense, limited the number of aircraft carriers that either navy could field in a potential conflict. While the Japanese built a series of sophisticated seaplane carriers, the Americans looked to much simpler tenders that would set up advanced bases in lagoons and inlets and service aircraft there.

A seaplane tender housed the aircrew aboard and included service and repair facilities (workshops, fueling stations etc.) but could not launch the seaplanes. These would take off from the water and would only be hoisted aboard the ship for servicing. American seaplane tenders did not have catapults, but did usually have large cranes and were intended to transport seaplanes to their forward operating areas.

	Shawmut at Guantanamo Bay, 1920. A Curtiss seaplane is moored to her stern.

The U.S. Navy's first seaplane tenders were a pair of minelayers, Shawmut and Aroostook, converted in 1919 and 1920 to support seaplanes. They provided mobile repair facilities, and Shawmut was usually found at Guantanamo Bay. In 1920 the Navy acquired the incomplete troop transport Somme and converted her into the airship tender Wright. A few years later she was converted again into a seaplane tender, and as a fairly large ship she could service over 30 planes.

The approach of war with Japan, and the Navy's relative lack of aircraft carriers, sparked a program of small seaplane tenders in the mid-1930's. Fourteen flush-deck destroyers were converted, with their four-inch guns replaced by a pair of three-inch anti-aircraft guns and their forward boiler removed to provide stowage for aviation fuel. They could make 23 knots on their reduced engine power, and retained an anti-submarine capability with a depth-charge track and a pair of projectors.

Nine old minesweepers of the Bird class also became tenders, with their sweeping gear removed to make way for aviation gear but few changes to their armament. In addition, the old aircraft carrier Langley was converted into a much larger seaplane tender, one very popular with aircrew as the large former flight deck provided ample work space that was lacking on the tiny ships.

Seaplane tender Onslow of the Barnegat class re-fuels a PBM flying boat, 1944.

The small converted ships lacked the space to provide all the facilities a seaplane squadron required, and the Navy ordered a class of over three dozen purpose-built small tenders as well. The Barnegat class had diesel propulsion and thus very long range, extensive anti-submarine capability, and a relatively powerful anti-aircraft armament. They could service a full squadron, and also were intended to escort larger seaplane tenders.

	Chincoteague, also of the Barnegat class, shows her sturdy layout. No sign of Misty.

Larger tenders were sought as well, and the big Currituck- and Curtiss-class ships could handle two squadrons each. These were purpose-built ships, with a heavy armament and huge stowage capacities for fuel and ammunition. Ten large merchant ships (the same standard C-3 hull that formed the basis for the escort carrier conversions) became seaplane tenders as well. Unlike the little ships, these tenders could hoist a full-sized Catalina flying boat aboard for servicing.

The Pacific War did not follow the pattern imagined by Navy planners, however, and before long the huge array of seaplane tenders was no longer needed. Nine of the converted destroyers were restored to their original configuration in 1943, and several of the Barnegat class were diverted to other uses as well - motor torpedo boat tenders and a catapult training ship. Eighteen of them would eventually be transferred to the U.S. Coast Guard.

We included a number of these American seaplane tenders in Second World War at Sea: Leyte Gulf. They are not aircraft carriers; they cannot launch aircraft on the high seas or perform other functions of a true carrier. The Second World War at Sea rules are still probably too lax in this regard, and so today we have some optional rules for their use.

Advanced Seaplane Basing

A seaplane tender (AV, AVD, AVP) may act as a seaplane base if it has remained in the same coastal zone for six turns without moving or conducting any other game function.

Interruption: If an enemy warship enters the same zone as a seaplane tender acting as a seaplane base, the base function immediately ends. If the seaplane tender moves, refuels, bombards or performs any other game function, the base function immediately ends. It may begin again if the seaplane tender remains stationary for six turns.

Capacity: A small seaplane tender (AVP, AVD) has a capacity of one step. A large seaplane tender (AV) has a capacity of four steps. Any number of seaplane tenders may provide the base function in the same coastal zone.

Anti-Aircraft: A seaplane tender does not cease to provide the base function if it is attacked by enemy aircraft and uses its anti-aircraft capability against them.

Anti-Submarine Warfare: Count a small seaplane tender (AVP, AVD) as a destroyer when resolving anti-submarine warfare (16.4).

Ship Data Sheet

Leyte Gulf was an enormous project, and the ship data sheets overwhelmed the first graphic designer who attempted them. Somehow we neglected to include the Ship Data for the American seaplane tenders in the final product. We've remedied that now, and you can download them here.

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