According to
James Cartlidge in January the averaged costs per vessel were very similar
- The contract for the three Batch 1 vessels had a value of £378 million = £126 million per vessel (not sure how this works as Lease 1 £50million, Lease 2 £52, exercising of buy clause £39) - Launched 2002-2003
- The contract for the five Batch 2 vessels had a value of £635 million = £127 million per vessel - Launched 2016-2019
I assume the full contract value for Batch 1 includes the separate spares and maintenance costs contract post purchase (Initial Batch 2 costs were included in the contract) and presumably an inflator so that the 2003/2008/2012 costs are at 2014 pound value.
Being of a certain age, the RN I joined had several classes/sub-classes based on and including the original Type 12 hull (Torquay was still in commission), 12M (Rothesays), and 12I (Leanders) - Batch 1, Batch 2, and Broadbeam - all of which had been further subdivided. My point being having a common hull doesn't mean they are the same vessel with the same role. The Batch Ones were primarily purchased to replace the Island class FPVs with a more capable vessel, and theoretically the Castle Class (an orphan class originally supposed to replace the Islands but defence cuts led to only 2 being built); that replacement ended up being the the one-off HMS Clyde, which like the Castles had a flight deck. As N_A_B said the Port of Spain/Amazonas Class was a budget version to fill a coast guard role. The Batch Twos, irrespective of the industry politics, enabled the RN to perform a policing, support of civil power role both more economically and without having to use increasingly scarce escorts off their main tasking. Another advantage which fits the forward deployment role is 66% longer endurance than the Batch Ones.
N_A_B my understanding is that Amazonas and River Batch 2 have the same length (90.5 m) and nominal displacement (2000 tons) - happy to be corrected.
The report stems from a pro-Global Britain think tank, like all think tanks it states its research is
rigorous, independent and policy-driven. Its funders include many who would benefit from a bigger better armed RN. The fact is until the next strategic review and a dose of the fiscal realities which both the currently major parties are ignoring, it's all a digital fantasty fleet wish list.
On a slightly different point, as I said in February regarding a proposed T32 design:
A crew of 50 (presumably 'core crew' i.e. supplemented by specialists for the 'autonomous systems' or a crewed aerial vehicle) is all fine and dandy but when spread across Cruising or Defence watchbills how will it be sustained? There is research that suggests a three watch system is the most sustainable for crew effectiveness and, physical and mental health.