Notes on Severn Estuary Crossing

A number of boaters had been asking about details of the Severn Crossing, so for their benefit, and our reference:

It is not obligatory to take a pilot but boaters would be recommended to take one, at least on the Sharpness to Portishead section. The consensus is that it is not necessary to have a pilot for the Portishead to Bristol leg. The Severn estuary has the largest tidal range in Europe, over 10.5 metres at Sharpness and 14.8 metres at Avonmouth, with currents running up to 8 knots. The flows are complex and the sea conditions can be dangerous to small craft, especially in the Shoots Channel under the M4 bridge.

Gloucester Pilots: 07774 226143. Book at least 48 hours in advance. Cost: £220.

Commercial traffic takes the pilot’s priority and they will not undertake a crossing if the weather is at or above Force 3.

Insurance companies have to be informed of a crossing and there may be an additional charge. We had to pay £30 (Towergate Insurance) but we did speak to other boaters who did not incur any additional charges.

It is recommended that the fuel is polished and the tank cleaned, although with our boat being 12 months old we were able to forego this. On the canals, the fuel is stable in the tank and any sediment will lay undisturbed in the bottom of the tanks. Once out on the estuary it is possible this sediment will be stirred up and consequently block the filters. There is a company called diesel-bug that have a branch close to Sharpness and will polish the fuel and clean the tanks. Cost: about £100.

Engine servicing should be up to date. Fuel filters should be changed prior to the crossing and a spare fuel filter carried, just in case.

Fuel and water tanks should be filled to provide extra ballast.

Boats need to be in Sharpness Lock 2 hours before high tide at Sharpness. There is a swing bridge to pass through first and the opening of this has be arranged 48 hours in advance. Sharpness Pier Head should be contacted to arrange lock and bridge bookings on 01453 811862.

Once in the lock CRT staff will give directions and pass mooring ropes. The pilot joins in the lock. Outside the lock you pass into a tidal basin prior to entry onto the river. It may be necessary to moor alongside a pontoon in the basin to await the correct state of tide before proceeding.

The tidal basin has to be exited at full power in order to be able to pass beyond the breakwaters and the engine should be capable of maintaining maximum power for 2 – 3 hours continuously.

It is not possible to reach Bristol Harbour on a single tide and an overnight mooring has to be arranged at Portishead Marina on 01275 841941. It is expensive, our 58½ foot boat cost £52.60.

The pilot disembarks at Portishead. Our pilot pointed out markers and targets for the crossing from Portishead to the mouth of the River Avon.

Portishead Marina give a time for departing to be able to reach Bristol on an incoming tide. The pilot also gave us the tide times. Bristol Harbour Office have to be advised of your ETD so they know when to expect you and have the lock prepared. 0117 903 1484. VHF Ch 14.

Bristol VTS also have to be informed of your ETD from Portishead. They monitor all movements in the Bristol Channel and will advise of any shipping movements likely to be encountered. 0117 980 2638. VHF Ch 12.

After leaving Portishead Marina Lock, follow down the breakwater on the portside keeping about 10m from it due to a build-up of silt. When 25m from the end of the breakwater, turn to starboard and head for a green buoy just to starboard of the end of Portbury Dock Breakwater. When near the buoy, alter course to clear the end of the breakwater.

Once pass the breakwater, head for the lighthouse at the end of the southern pier of Avonmouth Dock (the smaller one). When about 50m off the pier, start to turn and head for the Bristol VTS Control Tower, then gradually continue to steer into the River Avon. It is important to stay within the left-hand third of the channel due to mudflats for the first two bends in the river, keeping about 10m from the portside bank.

Bristol Harbour should be contacted at the Clifton Suspension Bridge and wait for the green light before entering the lock. In the lock your own ropes are used and need to be about 10m long.

The Harbour Masters Office has to be visited to arrange for, and pay, for moorings within Bristol Harbour as it is a separate entity from CRT. The cost of mooring in the harbour varies according to the length of stay, 3 nights cost us £94.50, but we were actually able to stay for 4 nights due to the weekend.

In addition to safety equipment required by the Boat Safety Scheme, buoyancy aids are required for all on board, including pets. A first aid kit is required. Should the trip be made during the hours of darkness, navigation lights are required, port and starboard and a stern light. While a waterproof torch is sufficient, a magnetic, battery operated inspection type light is probably best. But why would you want to do the crossing, such a unique experience, in the dark? If a pilot is not on board, flares may also be required.

An anchor is essential and should be made ready to be easily deployed should the need arise. The anchor system should consist of a suitably sized anchor, 5 – 10m of chain and a warp of about 25m of 12 – 14mm nylon rope.

A VHF radio is not essential but highly recommended as a primary source of communication. A mobile phone can be used, but the services that have to be contacted, especially Bristol VTS, primarily use VHF and this can also be used to listen in to other traffic.

While the cost of the venture may well mount, it is a fantastic and unique experience that will probably only be done once. While it is probably not for the fainthearted, we felt perfectly safe in the hands of our pilot, who remained a picture of calm throughout the whole experience and also provided a wealth of knowledge about the river and its environs.

Would we do it again?

Too bloody right!