Article 22 Shafts
In every vessel of 12 metres in length and over to which these Rules apply every shaft shall be so designed and constructed that it will withstand the maximum working stresses to which it may be subjected, with a factor of safety which is adequate having regard to:—
(a)
the material of which it is constructed;
(b)
the service for which it is intended;
(c)
the type and size of prime mover or motor by which it is driven or of which it forms a part.