Portsmouth Small Boat Channel update

Following some early observations, Queen’s Harbour Master Portsmouth have subtly revised the route of the Portsmouth Small Boat Channel.

Mariners are firstly advised that following the widening and re-orientation of the Portsmouth Approach Channel, as depicted on the newly published Admiralty Chart 2625 (2 March 2017), further adjustments have been made to the positioning of the Small Boat Channel that runs between 4 Bar Buoy (50 46.97N 001 06.48W) and Ballast Pile (50 47.62N 001 06.83W).

This latest Notice to Mariners supersedes LNTM 23/17 (Small Boat Channel Re-alignment) and should be read in conjunction with the regulations contained in General Direction 7/10 (Portsmouth Harbour Entrance – Approach Channel, Small Boat Channel, Swashway and Inner Swashway).

Portsmouth Harbour. Credit: Lieutenant Commander Shamus Roster/Royal Navy

2. Following the widening of the Main Approach Channel, the location of the Small Boat Channel over a somewhat narrower and steeper slope has resulted in a reduced tolerance for small craft straying out of the edge of the channel before they experience shoal depths. For this reason, the route of the channel and traffic management measures have been subtly amended in order to simplify the monitoring of vessel positioning and to reduce the potential for inbound and outbound vessels to force each other in to shallow water or the Main Approach Channel respectively.

3. Remaining approximately 50 metres wide throughout its length, the most significant changes are that all vessels using the Small Boat Channel are to leave 4 Bar Buoy to port, whether heading inbound or outbound, and that north of this point, the channel has been straightened from the route currently shown on new edition Chart 2625. Vessels navigating along the Small Boat Channel should now follow a line that passes from 4 Bar Buoy to approximately 25 metres east of BC outer (as depicted), keeping other passing small craft on their own port side.

4. Vessels approaching or departing the small boat channel to the south, particularly at low water, should follow the line of the port lateral buoys in order to avoid grounding on the SE corner of Hamilton Bank, turning to follow the line of the channel in vicinity of 4 Bar Buoy.

5. In vicinity of BC Outer (red beacon), all vessels should pass to the east of the beacon except those joining or leaving the Small Boat Channel at the Inner Swashway who are to leave it to port accordingly. This area can become extremely busy, particularly during the summer months, and mariners joining here should converge with caution and avoid forcing others out in to the middle of the harbour entrance. Similarly, all mariners should be alert to strong cross currents in this area which can sweep vessels in to the main channel.

6. All vessels less than 20 metres in length are to use the Small Boat Channel when entering or leaving Portsmouth, unless specifically exempted from doing so by the Queen’s Harbour Master. Furthermore, craft using the Small Boat Channel are legally required to comply with the measures contained in General Direction 7/10 (Portsmouth Harbour Entrance – Approach Channel, Small Boat Channel, Swashway and Inner Swashway). In particular, small craft are not to cross the Main Approach Channel until north of Ballast Pile or South of 4 Bar Buoy; should avoid loitering in the Small Boat Channel; should adjust their speed to remain in the Small Boat Channel rather than overtake and be forced in to the main channel.

7. The Harbour Entrance and Main Approach Channel is considered a Narrow Channel in accordance with the International Regulations for Preventing Collisions and Sea (COLREGS) and as such, all mariners are reminded that in accordance with Rule 9(b) “a vessel of less than 20 metres in length or a sailing vessel shall not impede the passage of a vessel that can safely navigate only within a narrow channel or fairway”; vessels over 20 metres in length are classed as the latter, are not to be impeded, and conversely are not permitted to enter the Small Boat Channel or Inner Swashway except in an emergency.

Further information can be found on the QHM Website at www.royalnavy.mod.uk/qhm/portsmouth/regulations/small-boat-channel