In a private watercraft I have undertaken multi-leg sea journeys to and from the UK via other countries (France, Ireland) without going through any kind of border control.

Are movements of this kind monitored?

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    You're specifically asking about a radar system designed to detect small boats for purposes of preventing smuggling (of drugs, immigrant, terrorists, etc.), right?
    – divibisan
    Jun 11, 2019 at 16:01
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    Yes I am. ... . .
    – 52d6c6af
    Jun 11, 2019 at 16:05
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    Would the radar capabilities of the vessels patrolling the UK's territorial waters count as "a radar system"?
    – phoog
    Jun 11, 2019 at 17:51
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    I would note that reporting requirements for private craft arriving from other EU countries allow them not to report if there are no third-country nationals aboard. No radar system will allow anyone to determine whether vessels that aren't reporting are in compliance.
    – phoog
    Jun 11, 2019 at 20:04
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    Additionally, radars are useless if there are not ships (or maybe helicopters) nearby available to intercept any suspicious vessel.
    – SJuan76
    Jun 11, 2019 at 21:06

2 Answers 2


Through Her Majesty's Coastguard, the Maritime and Coastguard Agency operates some vessels that have radar. Its vessels range from rigid-hulled inflatable boats to five cutters it claims are operated on a 24 hour day, 365 days a year basis (although at times some of the cutters have not been available page 59). The MCA also operates some helicopters and fixed wing aircraft for surveillance as well as search and rescue.

Border Force has a total fleet of five cutters and six Coastal Patrol Vessels (CPVs) too - these have radar - and a number of smaller vessels. The Navy also patrols the coast but it's difficult to find information on schedules and vessels.

According to a Policy Exchange report published in July 2018, Dover is the only place that has coastal radar. However, port authorities have radar and there are smaller radar systems dotted around the coastline, which can detect targets as close as the adjacent beach or up to 15 nautical miles.

In September 2018 the Sunday Telegraph reported that the Home Office has invited tenders for development of a "super radar system" for the Kent coast. This must be "able to identify and track small boats, but mainly RHIBs."

There are various difficulties with using radar to spot a vessel, from its characteristics (including size and shape) to radar clutter, which can mask its presence. Despite radar systems, trained radar operators, radar reflectors, AIS, lookouts and innocent intentions, sometimes even container ships and fishing trawlers fail to see each other and collide. Or ferries and pleasure yachts (see also and also).

The Government recommends that "Yachtsmen permanently install, not just carry on-board, a radar reflector or RTE that offers the largest Radar Cross Section (RCS) practicable for their vessel". The Government also says it's "essential for skippers to be aware that, notwithstanding the type of radar reflector fitted, in certain circumstances their craft may still not be readily visible on ships' radars."

So you can see that even if you were trying to be obvious you may have been completely missed. Or you were spotted and deemed not to be of interest.

The Policy Exchange report says "In the absence of any data collection about small boats arriving in the UK, is there some consistent surveillance of the coastline itself? No, it is simply too big." But "crossing the channel in a small boat is a hazardous exercise that requires traversing one of the busiest shipping channels in the world."

  • and as these systems are ship mounted, and the ships aren't there all the time, there won't ever be 100% coverage of any area. Areas near larger ports will have fixed radar installations manned 24/7 and active traffic control of the sealanes (with often mandatory pilot service for ships over a certain size) but if you stay outside those the chances of being spotted unless there's an actual search operation going on are slim.
    – jwenting
    Jun 12, 2019 at 3:50
  • Isn’t HM Coastguard just a SAR organization, not border enforcement?
    – cpast
    Jun 12, 2019 at 10:59
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    @cpast, my understanding is that HM Coastguard is in the position to supply intelligence about suspicious vessels to the Maritime Intelligence Bureau, a multi-agency entity set up by Border Force, helping to undertake the radar side of monitoring if circumstances arise, not enforcement. Looking into your question, I now learn from homeofficemedia.blog.gov.uk/2019/02/27/5232 that Border Force has a total fleet of five cutters and six Coastal Patrol Vessels (CPVs) too.
    – Lag
    Jun 12, 2019 at 11:19
  • Surely the MCA doesn't claim that each individual coastguard cutter is available 24/7/365? That would allow zero time for scheduled maintenance. Also, note that almost any ship of that size will have radar, for navigation and collision avoidance. And the cutters are operated by the Border Force, not the MCA/Coast Guard. Jun 12, 2019 at 16:10
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    @Lag I think that's a lazy way of writing "We have five cutters. We operate cutters 24/365." and shouldn't be interpreted literally. Jun 13, 2019 at 11:17

There is radar for traffic control, especially in crowded areas like the English Channel. It is mostly concerned with big ships, so smaller ones may be able to evade it, especially in high sea states.

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