- The frozen watch is a form of low berth travel.
The Frozen Watch: A ship may have low berths installed (...and competent medical personnel assigned). If low berths provide enough places for a 50% overage in personnel (...including ship's troops, if any), then the ship has a frozen watch. Replacement personnel are kept available in low berths for continuous replacement of casualties and battle losses; between battles, the frozen watch can be revived and used to restore lost crew. 
Frozen Watch Revival
Frozen Watch Revival: If a ship is equipped with a frozen watch, it may be revived to replace casualties taken in battle. Such a procedure requires at least three hours. At the end of the period, the new crew of the ship is revived and put to duty. Revival of the frozen watch may take place only, and such crew are rarely put back under frozen watch after being revived. 
Emergency Low Berths
Emergency low berths weigh one ton and cost Cr100,000; each contains four persons, all of whom share the same life support unit. Emergency low berths cannot hold the frozen watch. An emergency low berth can revive one conscious person at a time. 
The method of freezing living beings and reviving them was known to the Vilani, but their technology in this area was not well-developed. They used cold berths to house crew for long-duration space exploration missions before the invention of the jump drive, but the casualty rate on revival was near 50%. As a result, the Vilani had largely abandoned the technology for this use by the founding of the Ziru Sirka. 
With their better understanding of Human biology, the Terrans were able to develop a much safer hibernation system. This technology was used by the European Space Agency Long-range Colony Mission launched in -2470 (2050 CE). This mission included thousands of colonists and crew in cold sleep with the intention that they be awakened in shifts as the voyage progressed or when their specific skills were needed. 
Terran ships were utilizing this same concept to maximize the capacity of troop transports by the latter half of the Second Interstellar War. Around this same time, the Terrans deployed logistics vessels containing thousands of hibernating replacement crew, possibly representing the first use of the term “Frozen Watch”. After the end of the Interstellar Wars and throughout the Rule of Man, the Solomani maintained the practice of bolstering Naval crews with suspended personnel as needed. 
The acceptability of the frozen watch has waxed and waned throughout the history of the Third Imperium. During long periods of relative peace, the Imperium has dispensed with the concept and left the berths empty. But when wars begin, it is more expedient to move suspended crew members than active ones. Since about 1000, the Imperial Navy has stockpiled both naval and marine personnel at bases near areas of known concern. Imperial Capital ships designed and built since this time typically have a dedicated frozen watch. 
The personal toll of being separated from family and friends for a period of years makes frozen watch duty unpopular. During peacetime, it is usually assigned on a volunteer basis, but during wartime, thousands may be forced into suspension. Most often those so assigned are personnel who lack seniority or influence, including large numbers of draftees. There are persistent rumors of frozen watch personnel being lost by the Imperial Navy for decades. Most naval and marine veterans will have heard such rumors, and may hold a negative impression of frozen watch duty for this reason.