within the limits of deviation all such works, conveniences, appliances and apparatus as they from time to time deem necessary or expedient for the purposes of or in connection with or incidental to the construction, maintenance and use of the works authorised by article 3; and

within the harbour such works for the accommodation or convenience of vessels as they think fit, including, without prejudice to the generality of the foregoing, pontoons, stagings, quays, jetties, piers, walkways, bridges, approaches, slipways, landing places, berthing heads, boat lifts, mooring posts, buoys, bollards, navigation marks and lights.