Dupuy de Lôme and Gustave Zédé

Sketch of Gymnôte

Scientific American Supplement, No 1223, June 10, 1899, page 19611

Length 55 feet 11 inches
Beam 5 feet 10 inches
Displacement 30 tons

Gymnôte conceived by M. Dupuy de Lôme, but he died before the design was complete. The design was completed several years later by M. Gustave Zédé. Zédé added many modifications before presenting the plans to Admiral Aube, Minister of Marine. Construction of the Gymnôte was awarded to La Société des Forges et chantiers de la Méditerranée. M. Gustave Zédé was a director of the La Société des Forges et chantiers de la Méditerranée, which allowed him to closely supervise construction.

The keel was laid at the arsenal of Mourillon (Forges et Chantiers) near Toulon on April 20, 1887 under the care of M. Romazotti (first class sub-engineer) and Captain Krebs (designed her motor). Gymnôte was launched on September 20, 1888 and began trials on November 17, 1888.

Gymnôte spent most of her service life as an experimental craft. She was damaged in 1897 and underwent a major overhaul, which lasted until 1900. During war games in 1902, Gymnôte successfully attacked the French battleship Jaurequiberry without being seen. On March 5, 1907, Gymnôte ran aground and was seriously damaged. She was dry-docked in Castigneau. On June 19, a valve was accidentally left open and the Gymnôte was flooded with seawater. The damage was so extensive that the cost of repairs exceeded the replacement cost. She was sold for scrap in 1911.

Gymnôte was pointed at both ends and symmetrical about midships. The were 31 circular frames were strengthened with longitudinal braces. The shell was 6 mm thick amidships and 4 mm thick at the ends. The superstructure was a narrow deck with hatches at either end and a small conning tower 0.5 meters in diameter with port holes for navigation. A collapsible canvas coaming was also provided to shield the hatches from the sea. The coaming was not strong enough, however, to withstand much water pressure.

Gymnôte submerged by admitting water to three tanks - one in the center and one at each end. The tanks were filled by opening air cocks and emptied using compressed air or a Behrens’ rotary pump operated by an electric motor. She was fitted with rudders and diving planes forward of the propeller. An additional set of dive planes were added amidship during the 1897-1900 overhaul.

Gymnôte was originally fitted with a twin mirror optical tube. A "periscope" was added in December 1889. This periscope was replaced in 1898 with an apparatus developed by Daveluy and Violette. The original compass was replaced by a gyroscope developed by Captain Krebs in 1889, however, the gyroscope proved unreliable.

Electricity was originally supplied by 540 accumulators arranged as 6 batteries of 90 couples (2 pairs of 45 in tension). The accumulators were constructed by Mm. Coumnlin, Desmazures et Baillache. Each cell weighed 17 kilos 500. The elements were alkaline zincate of potash. The total capacity was 400 ampere-hours. Gymnôte had a speed of 7 or 8 knots submerged and a range on the surface of 83 km at 10 knots or 220 km at 6 knots. This battery was replaced in 1891 with a Laurent-Cély battery composed of 204 elements of five plates weighing 30 kilos each. The new battery reduced the range to 32 miles at 8 knots and 100 miles at 4 knots. The battery was replaced again in 1897.

The original Krebs motor had 16 poles and developed 55 hp. It weighed 2,000 kilograms (about 4,400 lbs) and was 1 meter in diameter. It was positioned as far aft as it would go, making it impossible to get past the motor to reach the aft bearing. Another problem was that the excitation used did not permit rapid stopping of the armature. The Krebs motor was eventually replaced by a smaller, more powerful Sautter-Harlé D.C. motor.

The crew consisted of 4 or 5 men including the commander. Armament consisted of two tubes capable of firing a 14 inch torpedo.

Burgoyne, Alan, Submarine Navigation: Past and Present,E. P. Dutton & Co., New York, 1903, pp. 281-283
Arthur Constantin Krebs website ( (website is written in French).
Memorandum of Information, Office of Naval Intelligence, Graf Collection, Paterson Museum.

Ó2000, 2001, 2002 Gary McCue

Gary W. McCue