In 1982, Boeing was awarded the main contract to develop the system, named the Sea Lance.

The Sea Lance was to be housed inside a watertight capsule which could be launched from an ordinary 21 inch torpedo tube.

The Mk 117 digital fire-control system provided targeting information to the missile prior to launch.

Both missiles were initially planned to carry a depth charge with a 200 kiloton W89 thermonuclear warhead.

In the mid-1980s, a conventional variant of this missile was proposed which would carry the new Mark 50 torpedo submarine-seeking weapon.