I think you're right. Portugal only has two submarines of any class, so it's got to be one or the other. In fact that's about 11% of the entire Portuguese navy you're looking at there, if we don't count coastguard vessels and suchlike. Good spot.Black and stealthy This is obviously quite a small diesel electric submarine, so not a UK vessel. She is flying the Union Jack as a courtesy but is also flying the Portuguese flag. Portugal has two 2000 ton submarines of the Tridente class with a crew of 33, so this is either the Tridente or the Arpao.
The designer of that needs being hung, drawn and quartered, that's got to be one of the ugliest ships I've ever seen.View attachment 242676
Ocean Shield [Bow Perspective] by Andrew Priest, on Flickr
Ocean Shield (IMO: 9628374) is an offshore supply vessel registered and sailing under the flag of Australia. Her gross tonnage is 8,368. She was built in 2012. Her overall length (loa) is 110.9 m. The ship is operated by the Australian Border Force (a federal government agency).
I photographed the Ocean Shield on her approach to berth at Fremantle Port on 10 September 2016.