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Supermarine Sea Otter

The Supermarine Sea Otter was an amphibious aircraft designed and built by the British aircraft manufacturer Supermarine.

It was the final biplane flying boat to be designed by Supermarine, it was also the last biplane to enter service with both the Royal Navy and the Royal Air Force.

The Sea Otter was developed as a refinement of the Supermarine Walrus, having been redesigned for longer range operations, to perform dive bombing and to operate from a wider range of vessels than its predecessor.

Prior to receiving the name Sea Otter, it was known as Stingray.

Due to Supermarine’s existing commitments to the Walrus and the Supermarine Spitfire programs, the aircraft’s development was protracted.

The maiden flight of the Sea Otter took place on 23 September 1938, while a production order was only issued in 1942 on account of the urgent wartime demands of the Second World War.

Upon its introduction during the latter years of the conflict, the Sea Otter was primarily tasked with maritime patrol and air-sea rescue duties by both the RAF and the Royal Navy.

Following the end of the conflict, numerous other operators procured the type for their own purposes, amongst these were the Royal Danish Air Force, Dutch Naval Aviation Service, and the Royal Australian Navy.


Sea Otter Mk I

Reconnaissance and communications amphibian aircraft.

Sea Otter Mk II

Air Sea Rescue amphibian aircraft.





39 ft 9 in (12.12 m) in rigging position


46 ft 0 in (14.02 m)


18 ft 0 in (5.49 m) folded


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


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)


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)


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)


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



1 × .303 in (7.7 mm) Vickers K machine gun in nose and 2 aft


4 × 250 lb (110 kg) bombs

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