Supermarine Sea Otter

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Sea Otter
A prototype Supermarine Sea Otter.jpg
Prototype of Sea Otter
Role Amphibian
Manufacturer Supermarine
First flight 23 September 1938
Primary users Royal Air Force
Royal Navy
Royal Danish Air Force
Produced 1942–1945
Number built 292
Developed from Supermarine Walrus

The Supermarine Sea Otter was a British amphibious aircraft designed and built by Supermarine; it was a longer-range development of the Walrus and was the last biplane flying boat to be designed by Supermarine; it was also the last biplane to enter service with the Royal Navy and the RAF.

Design and development[edit]

The main difference between the Walrus and the Sea Otter was in the mounting of the powerplant; the Walrus had a rear-facing engine with a pusher propeller and the Sea Otter's engine faced forward with a tractor propeller.

Sea Otter I of the Marine Aircraft Experimental Establishment in 1948

There was considerable development of the power plant/propeller combination during the design of the Sea Otter, which at its conception was called the "Stingray". The original test aircraft had a Bristol Perseus XI radial engine with a two-bladed propeller, which gave insufficient thrust so a two-position three-blade propeller was substituted, later changed again to a four-bladed type with the pairs of blades set at an angle of 35°, instead of the usual 90°. The first flight took place on 23 September 1938, but it was not until January 1942 that the Air Ministry placed a production order. Due to cooling troubles found with the Perseus, the power-plant was changed for production aircraft to the Bristol Mercury XXX engine driving a three-bladed propeller. The Sea Otter was used by both the RAF and the Royal Navy for air-sea rescue and patrol roles.

Postwar, Sea Otters were converted for civilian use. The cabin was soundproofed and fitted with heating. Seating for four passengers, a chemical toilet and a stowage for baggage were provided. As they were intended for use as Bush airplanes in remote areas, versatility was important. To allow cargo to be carried, the cabin floor was strengthened and fitted with lashing points, and the passenger seats made easily removable.[1]


Of the 592 aircraft ordered, only 292 were built due to the end of the Second World War. Eight aircraft were bought for the Royal Danish Air Force, and another eight were supplied to the Dutch Naval Air Arm. The colonial service of France purchased six Sea Otters for use in French Indochina.


Sea Otter Mk I
Reconnaissance and communications amphibian aircraft.
Sea Otter Mk II
Air Sea Rescue amphibian aircraft.


 United Kingdom

Specifications (Sea Otter)[edit]

Data from [4] Supermarine Aircraft since 1914[5]

General characteristics

  • Crew: 3-4
  • Length: 39 ft 9 in (12.12 m) in rigging position
  • Wingspan: 46 ft 0 in (14.02 m)
  • Width: 18 ft 0 in (5.49 m) folded
  • Height: 16 ft 2 in (4.93 m) with one propeller blade vertically downwards in the rigging position
  • Wing area: 610 sq ft (57 m2)
  • Empty weight: 6,805 lb (3,087 kg) amphibian
6,475 lb (2,937 kg) flying boat
  • Gross weight: 10,000 lb (4,536 kg)
  • Fuel capacity: 162 imp gal (195 US gal; 740 l) in two upper wing root tanks ; 11 imp gal (13 US gal; 50 l) oil
206 imp gal (247 US gal; 940 l) maximum fuel capacity as a flying boat
  • Powerplant: 1 × Bristol Mercury XXX 9-cylinder air-cooled radial piston engine, 805 hp (600 kW) for take-off
855 hp (638 kW) maximum at 4,500 ft (1,372 m)
740 hp (552 kW) maximum continuous at 5,000 ft (1,524 m)
  • Propellers: 3-bladed Rotol, 11 ft 3 in (3.43 m) diameter constant-speed propeller


  • Maximum speed: 163 mph (262 km/h, 142 kn) at 4,500 ft (1,372 m)
  • Cruise speed: 100 mph (160 km/h, 87 kn) at 5,000 ft (1,524 m)
  • Range: 565–725 mi (909–1,167 km, 491–630 nmi)
  • Ferry range: 920 mi (1,480 km, 800 nmi) with auxiliary overload tank
  • Service ceiling: 17,000 ft (5,200 m)
  • Rate of climb: 870 ft/min (4.4 m/s)
  • Time to altitude: at 5,000 ft (1,524 m) in 6 minutes 12 seconds
  • Wing loading: 15.1 lb/sq ft (74 kg/m2)
  • Power/mass: 0.0877 hp/lb (0.1442 kW/kg)
  • Take-off distance to 50 ft (15 m): 1,665 ft (507 m) from land
  • Take-off time from water: 24 seconds



No museum holds a complete aircraft. The Fleet Air Arm Museum (Australia) at Nowra, New South Wales, Australia, has the nose section of JN200, a Sea Otter which served with the Royal Australian Navy.[6]

See also[edit]

Related development

Aircraft of comparable role, configuration, and era

Related lists


  1. ^ "Civil Sea Otter". Flight: 383–384. 10 October 1946.
  2. ^ a b c d e f Halley 1980, p. 354.
  3. ^ Sturtivant and Ballance 1994, p.363.
  4. ^ Bridgman, Leonard, ed. (1947). Jane's All the World's Aircraft 1947 (35th ed.). London: Sampson Low, Marston & Co. pp. 84c–85c.
  5. ^ Andrews and Morgan 1987, p. 162.
  6. ^ Lambert, Roger. "RAN Sea Otter Dataplate" (PDF). Retrieved 16 May 2013.


  • Andrews, C.F. Supermarine Aircraft Since 1914. London: Putnam, 1981. ISBN 0-370-10018-2.
  • Andrews, C.F. Supermarine Aircraft Since 1914. London: Putnam, Second edition, 1987. ISBN 0-85177-800-3.
  • Halley, James J. The Squadrons of the Royal Air Force. Tonbridge, Kent, UK: Air Britain (Historians) Ltd., 1980. ISBN 0-85130-083-9.
  • Sturtivant, Ray and Theo Ballance. The Squadrons of the Fleet Air Arm. Tonbridge, Kent, UK: Air Britain (Historians) Ltd., 1994. ISBN 0-85130-223-8.

External links[edit]