Italy recently launched the first of seven Revel class Multipurpose OPVs (Offshore Patrol Vessels). These MOPVs are known in Italian as PPAs (Pattugliatore Polivalente d'Altura, or Multi-purpose Offshore Patrol) but they extend further the concept of multi-purpose ocean-going patrol vessels that is over a century old. The Revel class has the same basic hull and mechanical design but there are two major variations; Light (5,800 tons and lightly armed) and Full (6,200 tons and heavily armed). OPVs this large are no longer rare, Japan has been building them for decades and now China has done the same. The basic Revel design has hangers for two helicopters and at least one 127mm cannon along with some anti-aircraft missiles and autocannon. The Full Revel is armed like a warship with more elaborate electronics (including towed sonar array) and a larger crew of 120, compared to 90 for the light, or OPV, version. Both have berths for up 203 personnel, to accommodate specialists (commandos, disaster relief, or shipwreck survivors). Both have a long reach (9,300 kilometers at 28 kilometers an hour). Top speed is 58 kilometers an hour.
The Revel class is also another example of the European concept of a basic warship design that can be easily scaled up from corvette (2,000 ton) to destroyer (over 5,000 ton) type ships. Germany, Italy and France have been active supporters of this concept and the German Meko design, which first appeared in the 1970s, was the best and most prolific example of it. Israel’s large Saar type warships, for example, are Meko type ships.
Ocean-going OPVs are a 20th-century development, although the first steam-powered OPVs appeared in the late 19th century. These steam-powered steel ships tended to be larger and better able to travel longer distances. Nations like the United States and Britain, with worldwide coastal patrol responsibilities, had to develop large OPVs, or, as the Americans called them “high endurance cutters”. During the World Wars, the existing large OPVs often found themselves assigned to convoy duty to deal with the new (during World War I) and much larger (World War II) submarine threat. Since World War II larger OPVs become more common and when heavily armed were basically corvette or frigate class warships. For example, just before World War II began the U.S. Coast Guard built seven Treasury class cutters that were 2,500 ton ships that could easily be converted to ocean-going convoy escorts. And that’s what happened to these seven ships a few years after they entered service, and the U.S. entered World War II in 1941. After the war, the Treasury class was replaced in the 1960s by twelve of the larger (3,400 ton) Hamilton class. All the Hamiltons are still in service, nine of them with other nations the U.S. donated them to, often after upgrading them to warships. The Hamiltons were replaced by 4,600 ton Legend class cutters which are similar to the Italian Revel Full.
Long-distance OPVs have become common for most European navies. For example in mid-2015 Netherlands sent one of its four new (2012-13) seagoing OPVs to join the anti-piracy patrol off Somalia. It might seem odd to send a large coast guard vessel so far to patrol the Somali coast. But these new “Holland” class OPVs were designed for tasks like moving halfway around the world to help out with a peacekeeping operation.
It was back in 2007 that the Netherlands ordered four corvette sized warships for offshore patrol. These 3,700 ton, 108 meter (351 foot) long ships are large for "coast guard" operations but that's because the Dutch wanted vessels they could send to distant locations for peacekeeping if needed. Endurance (with onboard supplies) is 21 days and includes fuel to move 9,300 kilometers at 28 kilometers an hour. These OPVs are armed with one 76mm gun, one 30mm autocannon, two 12.7mm and six 7.62mm machine-guns. There are three workboats aboard, one fast rescue boat and two smaller fast special operations boats. There is a hanger and flight deck for a helicopter in the rear and one NH90 helicopter is carried. The ship is run by a crew of 54 although there is berthing for an additional 40 people (special operations, relief experts, technical or whatever). Top speed is 39 kilometers an hour. Each OPV cost $170 million. The lower cost (than most warships of that size) is due to the relative lack of weapons and high-end electronics.