What are the basic requirements of English common law as to seaworthiness?

MCA Oral Exam Questions

The vessel must be fit to encounter the "ordinary perils of the sea" (e. g. bad weather) and other incidental risks to which she will be exposed on the voyage. 

The common law recognises that owners cannot guarantee their vessels' seaworthiness once they have left port, so this obligation is imposed only at the start of the voyage, i. e. when the vessel leaves the berth either under her own power or under tow. Under the doctrine of stages, seaworthiness at each stage of the voyage, e. g. in dock, in a river, in an estuary, must be considered separately.