The Original

Vesikko

Vesikko was a single-hulled 250-ton boat that was to be the prototype of the Type II German boats, the "Einbäume". In some Finnish publications Vesikko is referred as a mixed-type, because most of its diving equipment was inside the pressure hull, but forward and aft main ballast tanks were outside. Vesikko was built from St 52 steel instead of St 42 that had been used in older boats. This means that the yield strength was 52 kg/mm² and the boat could dive to 100 m, whereas the maximum depth of the older boats had been 50-75 m.

Deplacement
tons Speed
knots Range
miles Dimensions
metres Max. depth
metres Torpedos Guns Mines

250/300 10.5/8.0 1500/50 40.9 x 4.1 x 4.2 100 5 x 53 cm, 3 bow tubes 20 mm Madsen none

Maximum length 40.9 m ---- Plate thickness 12-13 mm ----

Maximum beam 4.1 m ----

----

Length of the pressure hull 26.1 m ---- Plate thickness, tower 15 mm

Diameter of the pressure hull 3.9 m ---- Plate thickness, outer hull 3 mm

On top of the boat was wooden deck, that provided better stability. The boat was divided into seven compartments. The only pressure bulkheads was between Aft housing and Aft trim tank. Between Aft housing and Diesel and generator room was a watertight bulkhead. The compartments from stern were:

Aft trim tank inside the pressure hull

Aft housing for men

Diesel and generator room

Kitchen and diving tanks

Central

Officer room

Forward torpedo

Tank Volumes

Central main ballast tank 23.200 m³
Forward main ballast tank 17.900 m³
Aft main ballast tank 8.1 m³

Variable ballast tank 6.0 m³
Forward trim tank 1.91 m³
Aft trim tank 1.83 m³

Fuel tank 11.15 m³
Torpedo tank 4.4 m³
Drinking water 1.1 m³

Machinery:

2 x 350 HP Motoren-Werke-Mannheim
(MWM RS 127 S) Diesel ---- 9.6 tons of fuel ---- Range 1500 miles at 10 knots surfaced

2 x 180 HP Siemens electric motors ---- 62 cell battery group 6380 Ah total ---- Range 50 miles at 4 knots submerged

Two Carl Zeiss Nedinsco periscopes.

Crew: 2 officers, 5 senior petty officers, 6 petty officers, 7 men, total 20.

Deplacement tons	Speed knots	Range miles	Dimensions metres	Max. depth metres	Torpedos	Guns	Mines
250/300	10.5/8.0	1500/50	40.9 x 4.1 x 4.2	100	5 x 53 cm, 3 bow tubes	20 mm Madsen	none

Maximum length	40.9 m	----	Plate thickness	12-13 mm	----
Maximum beam	4.1 m	----			----
Length of the pressure hull	26.1 m	----	Plate thickness, tower	15 mm
Diameter of the pressure hull	3.9 m	----	Plate thickness, outer hull	3 mm

Central main ballast tank	23.200 m³	Forward main ballast tank	17.900 m³	Aft main ballast tank	8.1 m³
Variable ballast tank	6.0 m³	Forward trim tank	1.91 m³	Aft trim tank	1.83 m³
Fuel tank	11.15 m³	Torpedo tank	4.4 m³	Drinking water	1.1 m³

2 x 350 HP Motoren-Werke-Mannheim (MWM RS 127 S) Diesel	----	9.6 tons of fuel	----	Range 1500 miles at 10 knots surfaced
2 x 180 HP Siemens electric motors	----	62 cell battery group 6380 Ah total	----	Range 50 miles at 4 knots submerged