In fact was this design dealing with sub designs although using the same hull: namely one with single acting heavy oil engines and one with double acting gasoline engines. The gasoline fuelled engines supplied more power but were less economical with fuel consumption.
Dimensions 134’10” (over all) x 14’6 1/8” (maximum diameter) x 14’11 5/8| (maximum beam) and a displacement of 284 (light)-340 (total excluded the superstructure)-367 (total submerged) tons. Surface buoyancy 19.5% of surface displacement. Metacentric height while submerged 14”. Metacentric height light condition 8½”. Range of positive stability.
Fitted out with a conning tower of non-magnetic metal accessible from the hull by a watertight hatch. A well equipped navigation bridge was on top of this tower about 10 feet above the water level.
The heavy oil main engines were of the 4-cylinder vertical inverted type, with a total horsepower of 550hp the gasoline fuelled engines of the vertical inverted cylinder double acting four-cycle 6-scylinder type with a total horsepower of 800hp. Fuel bunker capacity around 2.500 US gallons when gasoline fuelled, in caste she was heavy oil fuelled were ballast tanks converted making it possible to double the bunker capacity. Main motors were 2-multipolar direct current motors delivering each 135 (continuously)-260 (for one hour) hp. Guaranteed surface speed with the main engines heavy oil fuelled was 13 knots. With the bunker capacity was the endurance 125 hours or 1.625 knots. With a cruising speed of 11 knots was the range 2.400 knots. Guaranteed surface speed with the main engines gasoline fuelled was 14 knots. With the bunker capacity was the endurance 50 hours or 700 knots. Guaranteed submerged speed was maximum 10¾ knots and an endurance of one hour. With a speed of 6 knots was the range 45 knots. Diving time from light to submerged 5 minutes and from intermediate to submerged in 3 minutes. The hull proper was constructed of steel allowing to dive to a depth of 200 feet.
Armament consisted of 4-45cm internal in the bow fitted torpedo tubes firing torpedoes with a length of 5,2 metres. Each tube was loaded and in this manner available for immediate response. The torpedoes were launched by air pressure controlled by the commanding officer or his substitute located at one of the two withdrawable periscopes. There were at the same time two tubes opened. When these two torpedoes were fired, could within seconds the other two tubes be opened. Standard was no storage for spare torpedoes available.
SourceArchive Kon. Mij. De Schelde 1875-1960 (Municipality Archive Vlissingen) T 214.802.