Submarines are 100 per cent. manned when deployed on operations. Surface ships use flexible manning systems and sail with the manning levels appropriate to their tasking. They routinely operate with greater than 5 per cent. gapping as a result of personnel being ashore for training, medical, or compassionate reasons, or assigned to augment other, higher priority tasking elsewhere. Detailed statistics on gapping from front-line units are not collated because only exceptionally, as in the case of HMS Cumberland referred to in my answer of 28 November 2006, Official Report, column 629W, are gapping levels reported by units.