VESSEL REVIEW | Alfred Merlin – Research vessel delivered to French underwater archaeology organisation

The Department of Underwater and Submarine Archaeological Research (Département des recherches archéologiques subaquatiques et sous-marines; DRASSM) of the French Ministry of Culture has taken delivery of a new locally-built vessel designed specifically for supporting underwater archaeological research missions.

Named after a famed 20th century French historian and archaeologist, Alfred Merlin was built by iXblue to a design by naval architecture firm Mauric to support and extend the range of the DRASSM's expanding maritime activities. Design work was done in compliance to Bureau Veritas class rules.

The new vessel has an LOA of 46 metres, a beam of 9.6 metres, a draught of 3.15 metres, and a displacement of 300 tonnes. A Cummins QSK50 1,641kW engine drives a fixed-pitch propeller via a ZF 7661 gearbox to enable the vessel to reach speeds of up to 15 knots while a cruising speed of 12.5 knots will yield a range of 3,500 nautical miles. Onboard space is available for 10 days' worth of provisions for the six crewmembers and 22 researchers.

Alfred Merlin also boasts FRP construction, which iXblue said is around 60 per cent lighter than steel. FRP also eliminates the need for anti-corrosion treatments and improves the vessel's underwater acoustic signature by reducing vibrations and noise that could otherwise affect data gathering. Mauric meanwhile said that the FRP that was used in the vessel's construction was recycled, this attribute being able to potentially reduce environmental impact even up to the subsequent dismantling.

Mauric said the hull will be monitored and the behaviour of the recycled FRP will be continually evaluated. To help the owners achieve this, optical fibres are installed in the bottom of the hull over the entire length of the vessel and on the front walls to record changes in displacement due to hogging and sagging effects on the vessel and impact pressure on the side shells forward.

The hull form was designed to enhance the comfort of the occupants without affecting speed performances. An advanced dynamic positioning system controls a set of four Schottel side thrusters – two each at the bow and the stern – to ensure improved station keeping in the vessel's main area of operations in the Mediterranean Sea.

The vessel will also have deck space for underwater robots that can reach depths of as much as 2,500 metres. The unmanned vehicles have dedicated launch and recovery systems (LARS) consisting of an A-frame, a 15-tonne crane, a seven-tonne hydraulic hoisting winch, and an electric hoist. A drop keel meanwhile contains a sonar and other sensors essential to underwater archaeology missions.

The data gathered by the sonar and the unmanned vehicles will then be processed on board Alfred Merlin with the aid of a large survey room and a dry laboratory. Compartments are also available for storing diving gear and archaeological conservation. The other accommodation spaces include cabins, a mess, a galley, a laundry room, workshops. and an onboard hospital.

Alfred Merlin is also equipped with a 7.5-metre rigid inflatable boat (RIB) to be used as a tender.

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