Jako
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zespół cech statku wodnego (w tym jachtu żaglowego) warunkujących bezpieczną, wygodną i - w miarę możności - szybką żeglugę w każdych warunkach pogodowych

ENG
http://en.wikipedia.org/wiki/Seakeeping
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Seakeeping ability is a measure of how well-suited a watercraft is to conditions when underway. A ship or boat which has good seakeeping ability is said to be very seaworthy and is able to operate effectively even in high sea states
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Factors affecting seakeeping[edit]
A number of factors affect seakeeping or how correctly the ship responds.

Size: A larger ship will generally have lower motions than a smaller one. This is because the relative size of the waves is lower.
Displacement : A heavier ship will generally have lower motions than a lighter one. Given that the wave energy is the same for each vessel and provides the exciting force, the one with the greater mass will have the lower accelerations.
Stability: A stable ship will tend to follow the wave profile more closely than a less stable one. This means that a more stable ship will generally have higher accelerations but lower amplitudes of motion.
Freeboard : The greater a vessel's freeboard the less likely it is to immerse the deck. Deck immersion is often a seakeeping criterion, as it affects mission capability in a number of ships.
Human factor: Often the most critical factors in seakeeping, especially in small vessels, are the experience and skills of the crew in extreme situations. Allied to these are avoiding seasickness, getting sufficient sleep, food and drink and staying injury-free for the duration of an extreme event.

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Note added at 4 dni (2014-09-25 19:01:47 GMT)
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DEFINICJE- seakeeping (ability) versus seaworthiness
SEAKEEPING (ability)

Seakeeping ability is a measure of how well-suited a watercraft is to conditions when underway. A ship or boat which has good seakeeping ability is said to be very seaworthy and is able to operate effectively even in high sea states.


SEAWORTHINESS
Seaworthiness is a concept that runs through maritime law in at least four contractual relationships. In a marine insurance voyage policy, the assured warrants that the vessel is seaworthy. A carrier of goods by sea owes a duty to a shipper of cargo that the vessel is seaworthy at the start of the voyage. A shipowner warrants to a charterer that the vessel under charter is seaworthy; and similarly, a shipbuilder warrants that the vessel under construction will be seaworthy.