How CNIS works

Dover CNIS is a Coastal Vessel Traffic Information Service (VTIS) mainly concerned with traffic passing through the area to ensure that essential information becomes available in time for on-board navigational decision making by the mariner.  The information service provides broadcasts at fixed times and intervals, when deemed necessary by the VTIS or at the request of a vessel.

CNIS broadcasts on VHF radio channel 11 every 60 minutes (every 30 minutes if  visibility drops below two miles) to give warnings of navigational difficulties, weather conditions and traffic information in the TSS.  This includes misplaced or defective navigational aids, hampered vessels, deep draught bulk carriers and tankers, vessels under tow, surveying vessels and unorthodox crossings such as cross channel swims.  A broadcast is also transmitted for any vessel that appears to be in contravention of the COLREGS, to warn other vessels that a potentially hazardous situation exists in a particular part of the TSS.

The radar antenna at Dover.  A similar antenna is used by the French Coastguard at the CROSS Gris Nez Rescue Centre

The microwave dishes on the mast at Dover receive additional radar data from radar sites at Fairlight and Margate

Ships using the TSS are automatically tracked by radar and evidence collected, which can be used in possible prosecutions of alleged contraventions of the COLREGS.  The system also collects data from vessels fitted with Automatic Identification System (AIS) transponders.  If the alleged offending vessel is bound for a UK port then action may be taken, but otherwise the evidence is forwarded to the vessel's Flag State for them to take action under the International Rules.  In the case of UK registered vessels, all information is forwarded to the MCA Enforcement Unit to investigate.

Part of the refurbished Operations Room at Dover MRCC

Traffic Lanes and Inshore Traffic Zones
Click here to download a chartlet of the Dover Straits TSS.

The Mandatory Reporting Scheme, in accordance with the Safety of Life at Sea (SOLAS) Convention 1974, regulation 8-1, Chapter V, was introduced in the Dover Strait TSS in July 1999, whereby all vessels over 300 gross tonnage are required to participate.  The service area covers a 65 mile stretch of  the Dover Strait/Pas-de-Calais and is bounded by a line to the east drawn from North Foreland to the border between France and Belgium; and by a line to the west drawn from the Royal Sovereign Light  Tower, through the Bassurelle Light Buoy (at its assigned position) to the coast of France.

Included in the 65 mile area are the Traffic Lanes and the Inshore Traffic Zones (ITZ).  The Traffic Lanes are to be used for NE and SW bound vessels and have been adopted by IMO in order to provide the safest possible navigational assistance to the mariner.  This takes account of the deepest water - there is a section of the NE Lane which is specifically designated a Deep Water Route (DWR) - and underwater hazards such as sandbanks and obstructions, i.e. wrecks.

ITZs are designated areas along both the UK and French coasts, the UK ITZ is bounded by a line drawn from Shoreham to the CS1 Light Buoy (marking the termination of the SW Lane) and a line drawn south from South Foreland to the SW Lane.  This area has restrictions; a vessel shall not use an ITZ when she can safely use the appropriate traffic lane within the TSS.  However, vessels of less than 20 metres in length, sailing vessels and vessels engaged in fishing may use the zone.  In addition, a vessel may use an ITZ when en route to or from a port, offshore installation or structure, pilot station or any other place situated within the ITZ or to avoid immediate danger.  This does not preclude the master of a vessel using the ITZ if he/she considers it necessary for the safety of the vessel and its crew providing the CNIS is advised of the intended route and reasons for the passage.

Monitoring vessel traffic in the South West Lane.  The three screens to the right of the picture provide the operator with live radar coverage of vessel traffic throughout the Dover Strait

Mandatory Reporting
The mandatory requirement from ships entering the area covered by the system is the Pas de Calais/Dover Strait Report; the short title for the ship report is CALDOVREP.  The report should contain the following information:

• Name of the ship, call sign, IMO identification number an MMSI number.
• Position Expressed in latitude and longitude.
• Course and speed of the ship.
• Vessel's draught.
• Route information.
• Hazardous Cargo, IMO class and quantity (if applicable).
• Breakdown, damage and/or deficiencies affecting the structure, cargo or equipment of the ship or any other circumstances affecting normal navigation in accordance with the provisions of the SOLAS and MARPOL Conventions.

Vessels on passage NE should report to CROSS Gris Nez traffic, on the French coast, two nautical miles before crossing the boundary line in the NE Traffic Lane.  Vessels on passage SW should report to Dover Coastguard on the English coast when within VHF radio range of  North Foreland, and not later than when crossing the boundary line in the SW Traffic Lane.  The majority of reports are received via VHF radio; however AIS transponder reports can be received by Dover Coastguard.  Radio and telephone traffic to and from Coastguard Co-ordination Centres is recorded for the purposes of public safety, preventing and detecting crime and to maintain the operational standards of HM Coastguard.

Exemptions from the CALDOVREP scheme
Cross Channel ferries are not required to participate in full, as the freight cargo can, and does, cover a vast amount of different categories and to expect a full manifest via VHF radio would be unreasonable.  Therefore ferries on a regular scheduled short sea crossing only have to advise Dover Coastguard or CROSS Gris Nez that they have departed.  Ferry companies hold the manifest which is available at immediate notice should this be necessary following an incident with a ferry.  Cross Channel ferry movements, whether freight or passenger, have reached more than 100 per day, with the main Dover -Calais route being by far the busiest with four main operators.  The other route taking freight and passengers is Ramsgate to Ostend.

Naval vessels, irrespective of nationality, are also exempt from reporting, this is due to the very nature of their role.  However, the vast majority comply with the reporting scheme, mainly to advise the CNIS that they are on passage.  No other details are requested.

There are approximately 500 shipping movements, W, NE and crossing, per 24 hour period, which include the following:

• Merchant vessels from all corners of the globe, carrying every category of cargo imaginable, from iron ore to wheat, and crude oil to sugar.
• Fishing vessels are from Channel Ports in the main, such as Belgium, France UK and the Netherlands, although other nationalities ply their trade on occasion.
• Other movements include a considerable number of pleasure craft, such as yachts, primarily in summer.  These are combines with other associated pleasure craft such as jet skis and cruisers.

There are a number of vessels with engine defects each year, most classified as minor problems; rectification is quick and the vessel continues on its intended passage without involvement of CNIS.  Other are more serious and can take some days to resolve.  These situations can develop without notice and require a vessel to anchor or drift not under command, possibly in a traffic lane of the TSS or near to the coast.  In order to prevent a collision or hazardous situation and protect the environment powerful tug known as an Emergency Towing Vessel ( ETV) has been chartered to patrol the TSS and will be called upon to guard or assist the vessel that has suffered an engine problem.  It will also warn other vessels of the situation.