There are, however, offsetting factors. The more powerful a Warshawski Sail, the slower its response time in realigning to a shift in the grav wave. This is potentially disastrous, but is, once more, offset to some extent by the ability of the more powerful sail to withstand greater stress. That is, it isn't as necessary to the starship's survival that it be able to reset or trim a sail to survive fluctuations in the grav wave about it. Put another way, a bigger ship with more powerful generators can "carry more sail" under given grav wave conditions than a smaller vessel and, all other things being equal, run the smaller vessel down.

But, of course, things aren't quite that simple. For starters, a smaller, less massive vessel gains more drive from the same sail strength. Because it is less massive, it accelerates more quickly for the same power. And the inertial compensator, marvelous as it may be, becomes more effective as its field area grows smaller and the mounting vessel's mass decreases, which means that a smaller ship can take advantage of its acceleration advantage over a larger vessel riding the same grav wave (and hence having access to the same "inertia sump") without killing its crew. If the smaller vessel can accelerate to .6 c(the highest survivable speed in hyper-space) before the larger ship, the larger ship's theoretical speed advantage is meaningless, as it can never overhaul. Under extreme grav wave conditions, the larger ship can maintain a greater effective acceleration, compensator or no, because the smaller ship's lighter sails are forced to "reef" (reduce their "grab factor") lest their generators burn out. This is particularly true in and above the zeta band, and few merchant ships ever venture that high. Even fairly small warships tend to have extremely powerful sails for their displacement, so that they can reach those higher bands, but smaller ships are simply unable to match the mass of a large ship's sail generators. This means that in some circumstances the larger ship can climb higher in the hyper bands and/or derive sufficiently more usable drive from a grav wave to offset its lower compensator efficiency.

In addition, smaller ships with less powerful sails can trim them much more rapidly and with greater precision. In wet-navy terms, smaller ships tend to be "quicker in the stays," able to adjust course with much greater rapidity and to take the maximum advantage of the power available to them from a given sail force. This means that a smaller ship with an aggressive sail handler for a captain can actually turn in a faster passage time over most hyper voyages than a bigger ship. There are, however, some passages (known to starship crews as "the Roaring Deeps") where exceptionally powerful, exceptionally steady grav waves operate. In these regions, the bigger ship, with its more powerful sails, is able to make full use of its theoretical advantages and will routinely run down smaller vessels.

In sublight movement, the larger vessel's more powerful sails (which equate to a more powerful impeller drive, as well) do not give it a speed advantage because of the nature of the inertial compensator. The curve of the compensator's most efficient operation means that a smaller vessel (with a smaller area to enclose in its compensator field) can pull substantially higher accelerations, and no amount of brute impeller power can create an artificial grav wave with a sufficiently deep inertial sump to overcome this fundamental disadvantage of a large ship. Capital ships thus are as fast as lighter warships in sustained flight but tend to be slower to accelerate or decelerate.

The tuning or trimming components of a Warshawski Sail generator are its most expensive and quickest wearing parts, and they wear out much more rapidly on more powerful generators with their higher designed power loads. Because of this, bulk carriers tend to use relatively low-powered sails and the lower hyper bands, which limits their practical speeds to perhaps 1,000-1,500 c. Passenger ships and those vessels specializing in transport of critical cargoes accept the higher overhead cost associated with more powerful sails and run in the range of 1,500-2,000 c. For the most part (though there are exceptions) only warships are designed around the most powerful sails and compensators their displacement will permit, giving speeds of up to 3,000 c. A bulk carrier's tuning components may last as long as fifty years between replacements and those of a passenger ship up to twenty years, but a warship is likely to require complete tuner overhaul and replacement as frequently as once every eight to ten years. On the other hand, a warship may spend decades "laid up" in orbit, making no demands at all upon its sails, so the actual life span of a given set of tuners may vary widely between ships of the same class, depending upon their employment history.

(3) The Mechanics of the Diaspora

It was discovered early in the Diaspora that the maximum practical safe speed for a sublight ship was approximately .8 c, as radiation and particle shields can not protect the vessel above that velocity.

The generation ships were built as complete, life-sustaining habitats oriented around the smallest practical self-sustaining population and designed to boost to that velocity at one gravity. In the long term, onboard gravity was provided through centrifugal force. In addition to their human passengers, the generation ships also had to provide for all terrestrial livestock and plants which would be required to terraform the colonists' new home for their survival. Even aboard these huge ships, space was severely limited, and many early colonial expeditions reached their destinations only to come to grief through the lack of some essential commodity the settlers had not known to bring along. This sort of disaster became less common after about 800 pd, when the original, crude hyperships made it possible to conduct extensive surveys of potential colony sites before the slower colony ships departed, but by that time the generation ships were a thing of the past, anyway.

In 305 pd, cryogenic hibernation finally became practical. It had long been possible to cryogenically preserve limbs and organs, though even the best anti-crystallization procedures then available were unable to prevent some damage to the preserved tissues. But where minor damage to an arm or a liver was acceptable, damage to a brain was not, and the early cryogenic pioneers' enthusiastic predictions about indefinite suspension of the life processes had proven chimerical.

It was Doctor Cadwaller Pineau of Tulane University who, in 305, finally cut the Gordian knot of cryogenic hibernation by going around the crystallization problem. He found that by lowering the hibernator's temperature to just barely above the freezing point he could maintain the physiological processes indefinitely at about a 1:100 time ratio. In other words, a hibernating human would age approximately one year for every century of hibernation, and his nutritional and oxygen requirements were reduced proportionately. Over the next several decades, Pineau and his associates further refined his process, working to overcome the problem of muscular atrophy and other physiological difficulties associated with long comatose periods, and eventually determined that optimum results required a hibernating individual to rouse and exercise for approximately one month in every sixty years (ie., after six physiological months), which remained a fixed requirement throughout the cryogenic colonization era.

What this meant was that the life support capabilities of a cryo ship could be vastly reduced in comparison to those of a generation ship. Moving at .8 c, the colonists experienced a 60% time dilation effect; in other words, each sixty-year period of hibernation used up one century of voyage time by the standards of the remainder of the universe. Thus an entire one-century voyage could be made without a single "active" period and would consume only 7.2 apparent months of the traveler's life span. Longer voyages would require periodic awakenings, but they could be staggered, permitting the currently roused crew to use only a fraction of the life support the entire crew would require. The result was to permit far larger numbers of colonists to travel on a given sized ship with a far lower subjective time passage.