Description

These appear to have been Wilton-Fijenoord versions of the Bofors 15 cm Mark 6. Marks 9 and 11 were for twin mounts while the Mark 10 was for single mountings. All these guns used horizontal sliding breech-blocks and had similar ballistics. Surviving ships were supplied with British-built munitions during World War II.

Actual bore diameter was 14.91 cm (5.87").

Gun Characteristics

Designation 15 cm/50 (5.9") Marks 9, 10 and 11
Ship Class Used On De Ruyter: Marks 9 and 10
Tromp: Mark 11
Date Of Design about 1935
Date In Service 1938
Gun Weight 7.38 tons (7.5 mt)
Gun Length oa 310.8 in (7.895 m)
Bore Length 293.5 in (7.455 m)
Rifling Length 239.1 in (6.073 m)
Grooves (4) 0.022W x 0.059D (5.55 x 1.5 mm)
Lands 0.165 in (4.2 mm)
Twist RH 1 in 30
Chamber Volume N/A
Rate Of Fire 5 - 6 rounds per minute

Ammunition

Type Separate
Projectile Types and Weights AP: 103 lbs. (46.7 kg)
HE: 101.4 lbs. (46.0 kg)
British AP: 99.8 lbs. (45.3 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge Dutch charges: 36.8 lbs. (16.7 kg)
British charges: 35 lbs. (15.9 kg)
Cartridge: 57.7 lbs. (26.2 kg)
Muzzle Velocity AP: 2,953 fps (900 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun Tromp: about 330 rounds 1
Others: N/A
  • ^The ammunition stowage per gun is given in "Cruisers of World War Two" as being 2,000 rounds, but I suspect that this is an error, with this figure actually being the total ammunition outfit.

Range

Range with 103 lbs. (46.7 kg) AP
Elevation Distance
29 degrees 23,200 yards (21,214 m)
45 degrees about 30,000 yards (27,400 m)

Mount/Turret Data

Designation Single Mount
   De Ruyter (1): Mark 10

Twin Mounts
   De Ruyter (3): Mark 9
   Tromp (3): Mark 11

Weight Single Mount
   Mark 10: 55,115 lbs. (25,000 kg)

Twin Mounts
   Mark 9: 156,970 lbs. (71,200 kg) for Turrets I and II. 155,650 lbs. (70,600 kg) for Turret III.
   Mark 11: N/A

Elevation Mark 9: -15 / +60 degrees
Mark 10: -15 / +60 degrees
Mark 11: -15 / +45 degrees
Elevation Rate N/A
Train Mark 9 and Mark 10: +147 / -147 degrees
Mark 11: about +147 / -147 degrees
Train Rate N/A
Gun recoil N/A
  • Jacob van Heemskerck had her turrets installed at the time of the German invasion and managed to escape to Britain. However, none of her fire control equipment had been installed, so her 15 cm guns were removed and shipped to the indies, most likely at Djamoeang reef.

Additional Pictures

Sources

"Dutch Naval Weapons of the early 20th Century" by Stefan Boon (unpublished manuscript)
"Naval Weapons of World War Two" by John Campbell
"Cruisers of World War Two" by M.J. Whitley
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Collection of Netherlands Institute for Military History (NIMH) Photographs (Dutch Language)
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Tony DiGiulian's personal data files

Page History

03 December 2008 - Benchmark
06 January 2009 - Added photograph of De Ruyter firing
30 May 2023 - Coverted to HTML 5, added photographs of De Ruyter and Tromp mountings, added information on guns, ammunition and mountings