Sea Lance

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Sea Lance was authorized in 1980 as a successor to both the UUM-44 Subroc and RUR-5 ASROC anti-submarine missiles.

Sea Lance was to be available in two versions, known as UUM-125A and RUM-125A. The former would be a submarine launched version, the latter surface launched.

In 1982 Boeing was awarded the main contract to develop the system, now named Sea Lance. By the following year it had become obvious that developing two different versions of the missile was too ambitious, and further development of the RUM-125 was suspended. RUM-139, a vertical launch model of the Asroc, was developed as a stopgap weapon in this role.

Sea Lance was to be housed inside a watertight capsule which could be launched from an ordinary 53.3 cm (21 in) torpedo tube. The Mk 117 digital firecontrol system provided targeting information to the missile prior to launch. After being fired the capsule would float to the surface where the rocket would ignite and fins would flip out. An inertial guidance system would direct the missile to the location of the target. Initial plans were to have the surface launched version operate in a similar manner, being launched from a MK 41 Vertical Launching System. When the missile reached the desired point the payload would separate from the missile and deploy a parachute to decelerate the payload. Both missiles were planned to carry a depth charge with a 200 kiloton W-89 thermonuclear warhead. Such a yield would have given the missile a lethal radius of around 10 kilometres. This, combined with the fact that the target would be unable to detect the missile until the payload hit the water, made it virtually impossible for a target to escape.

In the mid 1980s a conventional variant of the missile was proposed which would carry the new Mark 50 torpedo. The limitations in performance of this weapon combined with the limited accuracy of the missile meant that the conventional Sea Lance would only be effective out to ranges of approximately 65 km. This version was dubbed the UUM-125B.

A contract for full scale development was awarded in 1986. In 1988 it was decided to proceed again with the surface-launched RUM-125 version. The nuclear warhead was also put on hold in favor of a purely conventional missile.

In 1990 the entire program was cancelled for budget reasons. Although some effort was made to revive the project, this was unsuccessful. Today U.S. Navy attack submarines continue to lack any long-range stand-off anti-submarine weapon, while U.S. Navy surface warships make do with a new, vertical-launch version of ASROC.