Coastal Patrol, Offshore Patrol, and Maritime Defence – September 2004
The Danish Navy's four Thetis class OPVs caused much comment  at
Senate hearings on Canada's future maritime security. The
Thetis-class are roughly equivalent in size to the Canadian Halifax class frigates (see OPV comparison
tables). But, while the Canadian vessels were designed for NATO anti-submarine warfare, the
Danish Thetis emphasize Arctic patrolling.
Maritime Security: Of Sea-Nymphs & the North Cape –
A Look at Two Frigate-Sized Offshore Patrol
Designed for use off Greenland's east coast, the Thetis are double- hulled for ice protection.
Thetis are also very self-contained, carrying sufficient supplies that replenish- ment at sea is not
required despite a 8500nm (16000km) mission range.
The most distinctive features of the Thetis-class are the enclosed search radar antennae and main masts.
Such cladding is usually associated with reductions in a ship's radar signature but in this case – as
with the Icelandic Coast Guard's corvette-sized OPVs
– the most pressing concern is limiting ice build up. If sea-spray were allowed to form ice on the
structural framework of these components, these ships could become top-heavy and thus dangerously
The Thetis are well-suited to northern operations but not (as some Canadian reports have suggested) for a
mid-winter deployment into Davis Strait. The Danish
Navy employs a purpose-built cutter – the 31m Agdlek-class – to patrol waters off
Greenland's west coast. The use of the three 330t Agdleks in Davis Strait leaves the
Thetis free for use in the North Atlantic.
[ Update: On 23 April 2008, all four Agdlek class patrol boats
were auctioned off. The Agdlek are being replaced by two much larger Knud Rasmussen class OPVs.]
Broadly similar to the Thetis-class are the Norwegian Nordkapp-class frigate-sized OPVs. While
the Thetis are operated by the Danish Navy, the Nordkapps are employed by the Kystvakt
(Coast Guard - one part of Norway's navy). There are three vessels in this class
Nordkapp, K/V Andenæs, and K/V Senja (the 3240t Nordkapps are
supplemented by a newer 6500t ship, the K/V Svalbard). Like the Danish Thetis-class,
Nordkapps are slightly smaller than the Halifax-class, lighter, and have less than a quarter the
Other similarities with the Danish Thetis (and differences with the Halifax) are the
Nordkapps' ice-resistant hulls and their relatively modest armaments fit. The main gun is the same
57mm Bofors used by the Halifax frigates but, other than
light anti- aircraft weapons ( 3 x 20mm cannons and Mistral missiles), these Norwegian ships are unarmed.
Like the Thetis, Nordkapps use Westland Lynx onboard helicopters.
[ Update: Kystvakt also operate the icebreaking Svalbard
(upon which the AOPS will apparently be based). In
July of 2008, Norway announced that it will buy five smaller patrol vessels (Nornen, Farm,
Heimdal, Njord & Tor) currently on lease.]
Both of the two featured frigate-sized OPVs are designed with operations in Arctic waters as their priority.
Patrol is emphasized over warfighting. Both types have much to recommend them but how well frigate-sized OPVs suit
Canadian OPV requirements depends on how the specifications are drawn up. Emphasis should be placed on patrolling
Canada's east and west coast EEZs. Lumping on missions beyond the 200 mile limit will only compromise a CF
 The Danish Navy (Kongelise Danske Marine) refers to their Thetis-class as
'fisheries patrol vessels'. This innocuous description would be more convincing if these ships
didn't bear the name of a long line of Danish frigates and corvettes. It was the visit of a
Thetis-class OPV, the F359 Vaedderen, to tiny disputed Hans Island (between Greenland and
Ellesmere Island) that caught Canadian attention. The Thetis is marketed as the Standard Flex3000.
Like all other Danish StanFlex designs, the weapons and equipment are containized. On the KDM
vessels, these three containers house a 76mm gun and two cranes. The StanFlex design allows those
modules to be exchanged for others systems in about an hour at dockside.
Also see: Iceland's Coast Guard – a Case-Study for Corvette-sized