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").
| 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 |
| 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.
| Elevation | Distance |
|---|---|
| 29 degrees | 23,200 yards (21,214 m) |
| 45 degrees | about 30,000 yards (27,400 m) |
| Designation | Single Mount
De Ruyter (1): Mark 10 Twin Mounts
|
|---|---|
| Weight | Single Mount
Mark 10: 55,115 lbs. (25,000 kg) Twin Mounts
|
| 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.
"Dutch Naval Weapons of the early 20th Century" by Stefan Boon (unpublished manuscript)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
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