Britain's newest Offshore Patrol vessel, HMS Forth, which has formally entered her service will be used in border patrol operations.
HMS Forth is the first of five next generation Offshore Patrol Vessels set to be commissioned into the Royal Navy.
It is believed that this new fleet will be play a crucial role in counter-piracy, border control and fishery protection which is likely to be become increasingly important when Britain leaves the EU next year.
Speaking to Forces News at the commissioning in Portsmouth, Commander Robert Laverty, Commanding Officer HMS Forth, said:
"It's a really important day for us.
"It marks a stage of progression in HMS Forth as we bring her fully into service and get her out to sea, so a bit more work and we'll get her out to sea in mid-June," he explained.
The Batch 2 River Class are 30 feet longer than their predecessors.
This extra space means HMS Forth can take up to 58 crew, however only 34 personnel are needed to go to sea.
The vessel also has a flight deck which means Merlin helicopters will be able to operate from the ship.
Commander Sarah Oakley, Commander Fishery Protection Squadron, said:
"We've got a specially built area where we can have 50 embarked troops on board, so that Merlin helicopter can bring troops to us and then disembark them to the shore if required".
The first steel for HMS Forth was cut back in 2014 in Govan, Glasgow, where all the Batch 2 River class vessels are being esembled.
This was designed partly to fill the time between the building of the Queen Elizabeth Class of Carriers and the start of the Type 26 programme.
Over the next two years this commissioning ceremony will be repeated another four times as Medway, Trent, Tamar and Spey also join the fleet.