The Netherlands has ordered upgrade kits to so they can turn sixteen American-made MK-48 Mod 4 torpedoes into the latest Mod 7 versions. Each kit will cost about $5.3 million. This upgrade cost is more than twice what a new Mk 48 Mod 4 does but it reflects the enormous improvements in the guidance system and stealth of the Mk 48.
The Mk 48 was designed in the 1960s to replace the many World War II era torpedoes still in use. In addition to replacing the older torpedoes the Mk 48s were, from the beginning, easier to upgrade and built to get the most out of modern sonar and fire control systems being installed in new nuclear and conventional subs. This meant fewer problems maintaining the MK-48s and integrating them into new or upgraded submarine fire control systems. Later Mk 48 Mods made the torpedo even easier to upgrade. The Mk 48 was a major reason why Russia, despite building more than a hundred nuclear subs and nearly as many non-nuclear ones, always felt they were at a major disadvantage in underwater operations and combat.
The MK-48 entered service in 1971 and has been continually upgraded since then. There was a major upgrade in 1988 when the ADCAP (Advanced Capability) models entered service with the Mod 5. The initial “advanced” capabilities had to do with guidance and control. The previous Mod 4 had entered service in 1982 and was available until 2007. The mod 5 was available in 1988 until 2011, when the Mod 6 appeared. With this model major upgrades in the propulsion system were added. These included making the propulsion system much quieter, thus making the approaching Mk 48 more difficult for warships or other subs to detect when a Mk 48 was approaching or how the Mk 48 was changing course.
Another reason for all the upgrades is to deal with the growing number of electronic countermeasures subs or surface ships can use against an approaching Mk 48. The Mk 48 guidance system now contains more active (broadcasting) and passive (just listening) sensors to detect enemy countermeasures which can now include smaller, high-speed torpedoes aimed at the incoming Mk 48.
In the opening stages of a naval war, the objective is to achieve surprise by confronting the enemy with Mk 48 capabilities they were not expecting or prepared to handle. The enemy will adapt as quickly as they can but in the meantime, a superior M 48 can force enemy submarines and surface ships back to port or cause the enemy to suffer heavy losses.
That “surprise” element was one reason why the Mod 7 entered service in 2016. There are more upgrades in the works, keeping the Mk 48 way ahead of anything Russia, and now China has. You don’t hear much about the Mk 48 because underwater operations are more complex and involve very different tech than the more familiar, and visible land and aerial combat. Surface warships are equipped with a lot of different radars and other electronics and weapons to deal with aircraft and surface ships. The difficulty in detecting submerged submarines or the torpedoes they used has made surface ships more vulnerable to submarines. American subs and torpedoes pose the greatest threat which is why so many American allies use Mk 48s and pay to get the latest models or upgrade kits.
The MK-48 is a 533mm (21 inch), 1.7 ton weapon with a range of up to 74 kilometers (at 50 kilometers an hour) and a top speed of 102 kilometers an hour (at a range of 38 kilometers). The MK-48 can be controlled from the sub via wire guidance and has onboard sonar to assist in finding targets and avoiding underwater obstacles. There are numerous electronic devices on board to get around countermeasures. The MK-48 has a 295 kg (650 pound) warhead and uses a proximity fuze. Maximum depth is about 800 meters. The MK-48 is already used by the U.S. Navy as well as Brazil, Australia, Canada and the Netherlands. More allied navies would buy the Mk 48 but there are other modern, but less capable and much cheaper torpedoes available from Western nations as well as Russia and China.
Since World War II only three submarine-launched torpedoes have been used in combat to sink something. Only one was launched by a nuclear sub (a British boat). The other two were launched by Pakistani and North Korean diesel-electric subs. No MK-48 has ever been used in combat but new mods are tested under simulated combat conditions firing at a recently retired warship that is wired with sensors to record details of damage the Mk 48 inflicts.