Modifications to ships serving in this role often included the removal of weapons, and the erecting of housing structures on the main deck.

Upon release from receiving duties most ships were either decommissioned or transferred to a state's Naval Militia.

A relatively large number of hospital or ambulance boats have been used by various commands, squadrons, bases, districts, and theaters through most times of conflict and peace.

The ships served three missions: damage control / firefighting; casualty treatment / evacuation; and patrol / guardship.

Most notably, the evacuation ships took part in returning troops at the end of the World War II.

The Spearhead-class Expeditionary Fast Transport has a "Limited Medical Mission" role for the Flight II Variant of the ship.

The Flight II Variants are expected to be 338 feet long with a displacement of 2,400 metric tons.

[8] Starting with EPF-17, a new class of Joint High-Speed Vessel based on a catamaran hull will be the last of a series of ships the Navy expects to procure from the Austal USA shipyard in Mobile, Alabama.

It is expected to be between 1/3 to 1/2 the size of the Mercy-class hospital ships, and will not replace them, but supplement the US Navy's Enhanced Doctrine for Medical Support to Expeditionary Forces.