Baltic 57mm Firepower
During the Dansk-Hanseatic war (who doesn’t remember that like yesterday?), Christoffer, son of the Dansk king Waldemar IV Atterdag was killed in action by a cannonball on 11th of June 1363 during a sea-fight. This is one of the first instances of warships using cannon at sea.
The picture below is of a ship much more advanced than the galleys of the 14th century. Its the 238-foot long, 640-ton HSwMS Helsingborg of his majesty’s Swedish Navy. She is the second in the new class of Swedish Visby-class corvettes. These ‘stealth ships’ are constructed with a sandwich design consisting of a PVC core with a carbon fiber and vinyl laminate with good conductivity. Good conductivity and surface flatness means a low radar signature, while good heat insulation lowers the infrared signature and increases survivability in case of fire. The composite sandwich used is also non-magnetic, which lowers the magnetic signature. Composites are also very strong for their relative weight, and less weight means a higher top speed and better maneuverability. The composite weighs roughly 50% less than the equivalent strength steel.
The Helsingborg‘s angular design reduces its radar signature (or radar cross-section). Jan Nilsson, one of the designers, told BBC News Online: “We are able to reduce the radar cross-section by 99%. That doesn’t mean it’s 99% invisible, it means that we have reduced its detection range.” Even the 57 mm cannon barrel can be folded into the turret to reduce its cross-section.
Speaking of 57mm guns, that’s her Bofors Mk3 ripping off at 220-rounds per minute. In US service the Mk 3 is known as the Mark 110 Mod 0 and is in use on the new Legend-class National Security Cutters of the USCG as well as the two classes of Littoral Combat Ships (with some issues). The mounting has 120 ready rounds, and a total of 1,000 rounds in mounting, each a 6.1 kg (13 lb) shell with a range of 17,000m.
Besides the 57mm hood ornament, she carries 8 × RBS15 Mk2 antiship missiles, 4 × 400 mm torpedo launchers for Type 45 torpedoes, Mines, depth charges, and has provision for a dozen 127 mm ALECTO anti-submarine rocket launchers and 8 × Umkhonto SAMs.
So, there you have it, a stealth ship powered by state of the art gas turbines and diesel engines, still packing naval cannon some 600-years later.
Take that Christoffer.