I found this link;
http://www.navy.mil/navydata/cno/n87.../forgotten.htm
which gives these stats for S class;
Length:
225 feet Beam:
21 feet Draft: 17 feet
Displacement: 960 tons surfaced
1,130 tons submerged Surface Speed: 12-14 knots Submerged Speed:
10 knots Surface Endurance:
3,500 nm at 6.5 knots
Submerged Endurance: 20 hours at 5 knots
Complement: 4 officers; 39 enlisted men