Navigating Cardiff Bay

Navigating Cardiff Bay

As you enter Cardiff Bay, having passed through the locks, you will find yourself in a non-tidal fresh water environment that is replenished by the rivers Taff and Ely.

The immediate landmarks you will see are Penarth Quays Marina to port and the River Ely in front of you. As you enter into the Bay you will note Cardiff Bay Yacht Club on the headland slightly to starboard.

Speed limits

The speed limit for the Cardiff Bay inner harbour is a maximum of 5 knots.

The 5 knot limit also applies to boats using the River Taff.

Harbour Authority Licensed passenger carrying vessels are permitted to travel at a maximum of 7 knots in the River Taff. The speed limit for all other vessels using the River Taff is 5 knots.

Temporary speed restrictions

During water-based events, temporary speed restrictions may be established throughout the Bay. These will be notified through Local notices to mariners as well as by Harbour Authority staff managing the event.

Bay level and depths

Water levels in the Bay (the height of the water surface) are referenced to Ordnance Datum, and will generally be given as a height above this datum – AOD. Levels may vary between 4.0m and 7.5m AOD. The level at any given time may be obtained from Barrage Control.

The depth of water within Cardiff Bay is generally 2.5 metres or greater. Care should be taken when navigating around the wetlands area adjacent to the St Davids Hotel where port hand lateral marks indicate safe water.

Navigation within the Bay is relatively straightforward. However mariners should note that due to potential strong currents in front of the barrage sluices, vessels should keep to the correct side of the West Cardinal Mark.

Mariners should also be aware that the area directly downstream of the sluices outside of the barrage is an exclusion zone as high flows present a serious health and safety risk. Under no circumstances should mariners enter this area.

River Ely

There is a 5 knot speed limit for River Ely.

Please use caution when passing under bridges, and keep a look out for paddle craft and vessels emerging from mooring areas.



Pont y Werin Bridge

Pont y Werin Bridge is located about halfway along Cardiff Marina’s moorings.

The bridge spans over the River Ely, connecting Cardiff and the Vale of Glamorgan for pedestrians and cyclists. The centre section lifts for navigation and boat operations. It is managed by Barrage Control, who can be contacted on VHF Channel 18.

  1. Vessels may pass under the fully lowered bridge if there is sufficient air draft.
  2. When the three vertical red lights are extinguished either side of the bridge, you may proceed. The decision to proceed always rests with the Master of the vessel. Air draught boards are placed on both the downstream and upstream sides of the bridge to help mariners in their decision to proceed.
  3. Orange lights are illuminated under the lifting span at night to confirm that it is closed.
  1. When the bridge is being prepared to open or close, the lights on either side of the channel (both upstream and downstream) will show fixed red – meaning no vessels are to proceed.
  2. Navigation lights will flash red – if emergency action is required (maintain a listening watch on VHF Channel 18).

A timetabled lift operation is in place to help mariners plan effectively for locking out of Cardiff Bay Barrage.

The timetable, which is on a request basis via VHF 18, is as follows:

Lift at five minutes past the hour
Lift at 25 minutes to the hour

Mariners are advised to give Barrage Control good notice of their intention to navigate underneath the bridge, so that the lift can be planned during busy periods of operation.

Mariners are also requested to keep a listening watch on VHF 18 at all times, in case they need to be notified of any change to the timetable.

In addition, mariners should beware of two-way traffic on the river while passing through the bridge span, and be prepared to receive direction from Barrage Control staff via VHF 18.

Up-to-date information may be obtained from Barrage Control on 029 2070 0234 or on VHF Channel 18.

Cogan Spur Bridge

The Cogan Spur road bridge is a short distance above Pont y Werin. It is possible for small boats to navigate further upstream, but you are advised to be especially aware of your air draught. Cardiff Marine Village lies approximately 1.5 miles upstream of the river entrance, just beyond the Penarth Road Bridge.

River Taff

There is a speed limit of 7 knots for Harbour Authority Licensed passenger carrying vessels on the River Taff. The speed limit for all other vessels using the River Taff is 5 knots.

When navigating on the River Taff please use caution when passing under bridges. The river can also be subject to fast flows.


Butetown Link Road Bridge

As you travel upstream, the Butetown Link road bridge is clearly marked on either side by port and starboard markers. No other arches are navigable.

Please be aware of canoes and rowers in this area. Your wake can seriously affect light sculling craft, so be vigilant. There is also likely to be other river traffic in this area.

Wood Street Bridge

The depth of water beyond Wood Street bridge is less than 1.5m in many places, and navigation for pleasure craft beyond this bridge is not advisable.