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KHM Portsmouth / Safety and regulations / Regulations


This section details the procedures vessels under 20m using the small boat channel, who wish to cross the main channel close to the harbour entrance for Gunwharf Quays or the Town Camber.

HMS Dragon sailing towards the camera with a smaller patrol boat alongside it
A sign directing ship traffic within the harbour.


In the interest of safety all Small Boats bound for Gunwharf Quays/Town Camber are to enter harbour through the Small Boat Channel. Vessels are only to cross the main channel when they are to the north of Ballast Pile, and permission has been obtained from KHM on VHF Channel 11. Vessels fitted with engines are to use them from entering the Small Boat Channel until arrival at Gunwharf Quays/Town Camber. 

Context image of Portsmouth harbour


Small boats departing from Gunwharf Quays and the Town Camber are to obtain permission from KHM on VHF Channel 11 before crossing the main channel. All vessels are then to cross the main channel direct to Ballast Pile and leave harbour through the Small Boat Channel. Vessels fitted with engines are to use them until exiting the Small Boat Channel. If any of these vessels are not fitted with VHF radio, fixed or portable, then they are to be escorted by a marshalling craft or accompany another vessel so fitted.

A fishing vessel out at sea with a rib boat approaching the camera in the distance

Fishing vessels

Fishing vessels under 20 metres in length based in the Town Camber may enter and leave the harbour close inshore on the eastern side. They are nonetheless still to request approval to proceed from KHM on VHF Channel 11, giving their intended route. 

Inner Swashway

The Inner Swashway is closed to vessels of over 20m in length. Vessels over this size are to remain in the approach channel between the entrance to the Harbour and No 4 Bar Buoy. They should not enter the Small Boat Channel at any time except that they may do so when taking action to avoid collision under the COLREGS. The BC Outer red beacon is sited 100 yards to the south of Fort Blockhouse. Small boats transiting between the Inner Swashway and the Small Boat Channel are to leave this to port.

Harbour Entrance:

Extra caution is to be taken in the harbour mouth to ensure that small boats are not swept into mid channel from the Small Boat Channel by the strong cross-tide which is often present.


The Swashway is an important channel for shallow draught vessels approaching and leaving Portsmouth Harbour. Hovercraft and high-speed catamaran ferries often transit the area en-route to and from Ryde at speeds in excess of 24 knots. Hovercraft, being non-displacement craft usually navigate outside the Swashway in areas where depths are shallow. The Spitbank area, as a whole, is often used for yacht racing and regattas. Mariners in yachts and slow-moving craft are advised to maintain a thorough all-round lookout for the possible approach of high-speed ferries and other fast craft. Particular care needs to be taken to check the appropriate quarter before making an alteration of course. Mariners in high-speed craft are cautioned not to assume that other mariners, particularly those whom they are overtaking, are aware of their presence, and are to give them a sufficiently wide berth.

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