The Maritime and Coastguard Agency (MCA) has updated its guidance on the use of a radar reflector on boats less than 15m/49.2ft and under 150 gross tonnage. 

Marine Guidance Notice (MGN) 349 states that a radar reflector or radar target enhancer should be permanently installed, and offer the largest radar cross section (RCS) as practical for the vessel.

Commercial ships use radar equipment that operates in the ‘X’ band (9GHz) and the ‘S’ band (3GHz).

A radar reflector on a recreational boat should have a RCS of at least 7.5m² at X-Band and 0.5m² at S-band when mounted at a minimum height of four metres above sea level.

Just because you have a radar reflector, doesn’t mean you will be seen. Always keep a proper lookout, advises the MCA. Credit: Graham Snook/Yachting Monthly

The RCS should be maintained over a total angle of at least 280° of azimuth and not below this level over any angles greater than 10° (a null).

There should not be a distance of less than 20° between nulls.

For power driven vessels and sailing vessels designed to operate with little heel, such as a catamaran or trimaran, this performance should be maintained through angles of (athwartships) heel 10° either side of vertical.

For other vessels, the radar reflector should maintain this performance over 20° either side of vertical. Any radar reflector meeting the above requirements should comply with ISO 8729-1:2010.

If the radar reflector meeting these standards are unsuitable for boats under 15m LOA, then owners are recommended to fit a radar reflector to the older standard EN ISO 8729:1998, which has been retained for type approval under the Marine Equipment Regulations (MSN 1874) for radar reflectors for lifeboats and rescue boats.

It should be noted that Echomax has emailed Yachting Monthly to say it has contacted the MCA to express concern over their mention of ISO 8729-1:2010, as currently, there are no known passive radar reflectors which meet ISO 8729-1:2010 which has a volume limit of 0.5m3 and weight limit of 5kg.

In response, the MCA said:

‘The notice will not be amended as it can’t be confirmed 100% that there are no products of this type currently on the market, but it is highly likely during our research that this is the case.

In reference to 3.1.3 of the amended MGN:

‘3.1.3 However the above standard results in a large reflector that may be unsuitable for vessels under 15m overall length, in which case Owners and skippers of craft less than 15m overall length are recommended to consider fitting a radar reflector to the older standard EN ISO 8729:1998, which has been retained for type approval under the Marine Equipment Regulations (MSN 1874) for radar reflectors for lifeboats & rescue boats.’

EN ISO 8729:1998 remains in force until a product is placed on the market approved to ISO 8729:1.’

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The MCA is also advising skippers that in certain circumstances, their boat may still not be readily visible on ships’ radars, even when fitted with a radar reflector or a radar target enhancer, and that this does not replace the need for a proper lookout at all times.

MGN 349 was initially published following the deaths of three sailors aboard the Sailfish 25, Ouzo overnight on 20-21 August 2006.

Rupert Saunders, 36, Jason Downer, 35, and James Meaby, 36, all died when their yacht was sunk six miles south of St Catherine’s Point on the Isle of Wight after a collision with the P&O ro-ro ferry Pride of Bilbao.

Radar reflectors should be mounted at a minimum height of four metres above sea level. Credit: Graham Snook/Yachting Monthly

A report by the Marine Accident Investigation Branch (MAIB) found that Ouzo had not shown up on the ferry’s radars and the bridge team on Pride of Bilbao had not seen the yacht until is was very close ahead.

The officer on watch made a last minute manoeuvre to avoid Ouzo and believed he had been successful, although he did not contact the yacht crew to confirm this, and instead relied on seeing, what he thought, was the yacht’s stern light.

The MAIB concluded that the Pride of Bilbao had collided with Ouzo, or passed so close that the yacht had been swamped or capsized by the ferry’s wash. The yacht was never recovered.

The MAIB did commission a report by QinetiQ to carry out research into a number of common types of radar reflectors to compare performance with International Standards (ISO 8729).

The recommendations included:

• Using a Sea-Me radar reflector where power is available;
• Making sure the RCS of the radar reflector was a minimum of 2m²
• Not using a 4” or 2” tube reflector due to its poor performance.

Details of MGN 349 can be found here.

Details of the full MAIB report into the sinking of Ouzo and the QinetiQ Radar Reflector report can be found here.

Please note this article was updated on 23 November 2022 after YM was contacted by Echomax about the updated MGN 349 guidance, to inform us that there are currently no known passive radar reflectors which meet ISO 8729-1 which has a limit of 0.5m3 and 5kg.

Enjoyed reading Updated guidance on fitting a radar reflector to boats under 15m?

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