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Seamanship on the Thames

Revision as of 11:49, 22 February 2021 by Richardphillips (talk | contribs)

This article is adapted from an article by the Port of London Authority. The edits are principally to remove content only relevent upriver from Tower Bridge.

Key rules for sailing on the tidal Thames

As the tidal Thames is linked to the sea, all vessels need to follow the ‘International Regulations for Preventing Collisions at Sea’ (“Col Regs”). You can read the rules in full here. (There are other local byelaws that relate to rights of way with other vessels, which will be explained further below.) The main basic rules are: When navigating in the tidal Thames vessels must keep as near to the starboard side of the fairway at all times, as is safe and practicable, or follow the recommended routes shown on our Recreational Users’ Guide. For the avoidance of doubt, this does not mean that you can cross from one bank to another to tack along the river. If you are crossing the river, it is to get to a set location for a particular purpose (i.e. to leave/get to a mooring) and you must not tack, cross or enter the fairway so as to obstruct another vessel proceeding along the fairway.

  • KEEP A GOOD LOOK-OUT at all times, BEHIND YOU as well as in front
  • If you find yourself approaching another vessel head-on, you should sound one short blast and keep to the STARBOARD (RIGHT)

When entering the river from a lock, pier or berth do not cross in front of another vessel.

At bridges, use the most starboard arch available to you provided it does not compromise your safety. (See the specific navigation advice for different areas of the river below, for more advice.)

Our byelaws contain rules which supersede some of the International Collision Regulations. For example

  • a vessel must not cross or enter a fairway so as to obstruct another vessel proceeding along the fairway.

Navigating in fog or restricted visibility

Navigating in restricted visibility is not an activity that the PLA recommends that any sport, leisure or recreational boaters should undertake on the tidal Thames. No attempt should be made to get underway when visibility is less than 200m and should you already be underway during an outing, you should find a safe haven as soon as reasonably practical.

Should the Master of a vessel decide to navigate in restricted visibility, you must have a comprehensive understanding the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs), in particular Part B (Steering and Sailing Rules) both Section III (Rule 19) – Conduct of vessels in restricted visibility and Section I (Rules 4 to 10 inclusive) – Conduct of vessels in any condition of visibility.

Put simply:

  • A rigorous lookout should be maintained – by sight, sound and any means necessary
  • Navigation Lights are operational
  • Radar, if fitted, is setup appropriately and utilised to assist you in navigating in fog however it should not be solely relied upon but it is an incredibly useful aid to your navigation
  • Navigate at a safe speed to ensure effective action can be taken to avoid a collision.
  • MGN 369 – Navigation In Restricted Visibility contains further guidance.

Small vessels can also vastly improve their detectability by using AIS. An AIS transceiver can also assist small vessel crews in the early detection of ships, as well as showing names, call signs, speeds and headings of vessels in the locality to improve situational awareness.


At times the wash, or waveheight, on the Thames can get heavy. The steep river walls reflect, rather than dissipate, the wash so it can be particularly rough at high water during busy traffic periods. The Thames is classified as ‘Category C’ and ‘D’ with waveheights of up to 1.2m and 1.5m, so vessels should be suitable for the conditions.

Before navigating on the tidal Thames

Ensure you have planned your passage; taken into account the tide times; made bookings with any locks; and checked the weather and ‘Fluvial Flow’ guidance. Check our Notices to Mariners page for anything that may affect your journey, such as river closures and bridge maintenance.

Everyone on board a recreational craft navigating on the tidal Thames should wear a lifejacket. The river is cold and fast flowing and can be harsh and unforgiving.

Pre-passage checklist

check your backup engine (if fitted) is running satisfactorily check your bilge pumps operate correctly check the stern gland greaser is topped up and operates correctly check the horn is working correctly check the steering is working correctly check your anchor is correctly attached and ready to deploy (See Equipment section below) Entering the tidal River Thames Contact “London VTS” (Vessel Traffic Service. See contacts below) with:

  • Name of your boat
  • where you are entering the tidal Thames and your destination
  • The time you expect to be on your way
  • how many people are on board
  • VTS can pass any pertinent navigational information to you too, such as river closures or bridge arch closures.

Always be aware of traffic moving up and down the river and enter the tidal Thames only when safe to do so.

VHF marine radio

We strongly advise all vessels to carry VHF, though VHF is only required for vessels above 13.7m.

(NB: exemptions exist for vessels travelling in a flotilla or convoy above Greenwich.)

You should monitor VHF Channel 14 when between Teddington, through central London to Dagenham (Crayfordness). Below here, monitor Channel 68 until Southend Pier where Channel 69 then takes over.

If there is no VHF radio on board, the person in charge of navigation of the vessel should report to the London Vessel Traffic Service (VTS) by telephone (0208 855 0315 west of Dagenham, 01474 562215 east of here) prior to entering the tidal Thames.

Most chandleries sell VHF handsets, along with the ‘Ship Portable Radio Licence’ required for a VHF Digital Selective Calling (DSC) Handset. Contact your local chandlery for more advice on this.

If coming from the non-tidal Thames, Lindon Lewis Marine at Shepperton offer a VHF rental service. They can also supply river user guides and help with passage planning. (

Note: An RYA ‘Short Range Certificate’ (SRC) is the minimum requirement to use a VHF or VHF DSC radio (unless It is an emergency situation when anyone may use the radio to call for help) as well as appropriate licenses from OfCom. Contact OfCom and the RYA for more information.

Vessel construction and equipment

The tidal Thames is categorised by the MCA (Maritime Coastguard Agency) as a ‘Category C’ waterway down as far as Gravesend. This means that you can expect wave heights of 1.2m, so it is important to ensure your vessel and the equipment it carries is up to the task. (This increases to ‘Category D’ downriver of Gravesend.)

We recommend the following equipment when navigating on the tidal Thames:

  • Lifejackets: approved by MCA or under the Marine Equipment Directive (MED), or should comply with BS EN 396: Lifejackets and personal buoyancy aid of 150N, or BS/EN 399: Lifejackets and personal buoyancy aids of 275N
  • a VHF set (mandatory for some vessels)
  • mobile phone (in a waterproof pouch)
  • water resistant torch
  • suitable boat hook
  • appropriate first aid kit
  • navigation lights if navigating during darkness or reduced visibility
  • ropes for mooring the vessel and for towing
  • minimum of one 12kg anchor, attached to a designated strongpoint by 5 metres of 6mm short link chain and 25m of 12mm rope.

Additional information from the RYA:

An AIS transponder (Automatic Identification System) is of a great benefit. An AIS transceiver can assist small vessel crews in the early detection of ships, as well as showing names, call signs, speeds and headings of vessels in the locality to improve situational awareness.

Licensing and certification

Although there is not a legal requirement for the person in charge of a recreational craft or ‘pleasure vessel’ to have a formal qualification, the tidal Thames is not for novice or inexperienced people. A good degree of boating knowledge and experience is needed before venturing on to this complex and challenging river.


  • vessels that are hired or chartered are not considered to be pleasure vessels.
  • a vessel carrying more than 12 passengers is not classed as a pleasure vessel, but would come under the definition of a ‘passenger vessel’. The vessel and the skipper would then require appropriate licences from the Maritime Coastguard Agency (MCA). Contact your local MCA office for further details.