These Regulations govern transfers consisting wholly or mainly of oil between ships, known as ship-to-ship transfers. The two types of ship-to-ship transfer which are governed within the Regulations are cargo transfers and bunkering operations.
The Regulations prohibit cargo transfers unless they are carried out within harbour authority waters or within the permit area (regulation 4). They also provide that cargo transfers must not be carried out within harbour authority waters unless they are authorised by the harbour authority or the cargo transfer is a lightening operation (to lighten the ship to enable it to move to shallower waters) or a consolidation operation (to consolidate cargo for bunkering operations) (regulation 5).
Source: HMSO.