Défense
Ocea delivers all-aluminium OPV

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Ocea delivers all-aluminium OPV

Défense

Join us for a guided tour of the Fouladou, the first offshore patrol vessel by Ocea; also the largest aluminium OPV built in Europe and the Senegalese Navy’s new flagship.

OPV Fouladou was delivered to Dakar, its homeport, in November. This state-of-the-art vessel has a length overall of 58 metres, a beam of 9.4m and was built at Ocea’s shipyard at Sables d’Olonne on France’s Atlantic coast.

 

Commander Diawara on the bridge (© Mer et Marine - Vincent Groizeleau)

Commander Diawara on the bridge (© Mer et Marine - Vincent Groizeleau)

Wake watching (© Mer et Marine - Vincent Groizeleau)

Wake watching (© Mer et Marine - Vincent Groizeleau)

Stable and quiet

During trials, OPV Fouladou recorded a top speed of 26 knots aided by a slight current, 2 knots more than the contract specification. The ship is remarkably quiet and stable, even without using the Naiad stabilisers. Travelling at high speed, there is little vibration on the bridge and remarkably little noise, even with the outside door wide open. “The new platform’s stability and low noise levels are the result of know-how we’ve developed over a period of 30 years or more. We have plenty of experience in building aluminium hulls and proven design skills enabling us to deliver economical high-performance vessels that meet our clients’ needs at competitive construction costs. We invest a great deal in R&D and our in-house design team has the latest hardware and software, including digital simulation tools.”

“To optimise the design of this new-generation OPV, we tested no fewer than 27 hullforms. Soundproofing and noise control are also Ocea strengths. We focus on noise control from the beginning of the design phase, drawing on lessons learnt from every ship we’ve built. We introduced a number of innovations when designing the survey vessels we built for Indonesia and all proved highly successful,” said Fabrice Weinbach, Ocea’s head of Maritime Security & Safety.

 

Fabrice Weinbach, Ocea’s head of Maritime Security & Safety, and Paul-Éric Juin (© Mer et Marine)

Fabrice Weinbach, Ocea’s head of Maritime Security & Safety, and Paul-Éric Juin (© Mer et Marine)

Better than expected

The stability, speed and fuel consumption data recorded during the first few weeks of operational service exceeded expectations. The design team and everyone else at the Ocea shipyard was pleased to learn that in-service performance was better than the client’s specifications. Proud of its track record in patrol vessels ranging from 20 to 35 metres and others approaching 60 metres — most importantly the two OSV 190 survey vessels delivered to Indonesia in 2015 — Ocea is pleased indeed that its first OPV, with its decidedly different hullform compared to the OSVs, is proving such a success.

 

The Fouladou under construction at Ocea’s Sables d’Olonne shipyard (© Ocea)​​​​​​​

The Fouladou under construction at Ocea’s Sables d’Olonne shipyard (© Ocea)​​​​​​​

The many advantages of aluminium

Because aluminium hulls are lighter than steel ones, they require less power to achieve the same speed while burning less fuel. “For a standard mission profile of the type identified by the Senegalese Navy, and a 20-year lifetime, we calculated that an OPV like the Fouladou will burn 5 million litres less fuel and emit 37%, or 14,000 tonnes, less carbon dioxide than a steel-hulled vessel of the same size designed for the same missions. Aluminium’s fuel savings are thus a real benefit.”

“For operators who specify aluminium hulls, the choice also means vessels that are more respectful of the environment at a time when the international community is increasingly aware of climate change and the challenge of meeting the COP21 targets. In this respect, the benefits of aluminium go far beyond reduced fuel consumption. Aluminium-hulled ships also consume less oil and far less paint as the corrosion-free metal does not have to be constantly repainted. While it is true that aluminium production is energy intensive, it is also true that its recycling is more efficient. Aluminium can be recycled up to ten times, compared to three for steel. Also, each recycling requires just 5% of the energy needed for initial production.”

 

Forward deck (© Mer et Marine - Vincent Groizeleau)​​​​​​​

Forward deck (© Mer et Marine - Vincent Groizeleau)​​​​​​​

Dependable, provided it’s used wisely

To date, navies have generally refrained from moving to aluminium hulls for large platforms, their chief concerns being long-term structural strength and the metal’s response to fire. Ocea’s engineers are confident that these fears are overstated: “We’ve been working with aluminium for over 30 years and built a range of vessels for demanding professional applications. Our design expertise and our rigorous sample-and-test policy — which goes far beyond the requirements of any classification society — give us the utmost confidence that we have mastered the challenges of metal fatigue and that our products are as rugged as any made of steel. To date, not a single Ocea vessel has encountered the least problem involving metal fatigue or premature ageing. The facts show that we master the technology. Unfortunately, the same cannot be said of all shipyards, which explains why some have encountered problems while others have not.”

The fact that Ocea hulls carry a ten-year guarantee further demonstrates the company’s confidence in its know-how. On the question of aluminium’s fire response, Fabrice Weinbach says, “each material has its own characteristics. When exposed to intense heat, composites melt and steel buckles. In the event of a shipboard fire, the most important thing — irrespective of the final result — is how quickly the fire is detected and how quickly the fire can be put out. Our vessels meet the highest standards in these areas. Each space is fitted with both heat and smoke detectors as well as with the requisite firefighting equipment. The engine room, for instance, is equipped with a Novec inert gas fire suppression system.

 

Engine room (© Mer et Marine - Vincent Groizeleau)​​​​​​​

Engine room (© Mer et Marine - Vincent Groizeleau)​​​​​​​

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