2: Whether RN OPVs shall be cheap or shall be with at least River B2 hull standard and with at least a 57mm gun.
If the tasks is law enforcement and HADR, merchant-ship standard hull (*1) and "a 30 mm gun + 4-6 small armes" armament is good enough.
But, when someone think it is to fight against Iranian fast-boats or Hoiti-rebels suicide-drones or even SSMs, better armaments like, 57mm/40mm 3P guns and/or Phalanx CIWS comes into my mind. (If it carries CAMM or RAM, it is already a light frigate and here comes "T31 as of now". Not an OPV).
In this case, what kind of hull standard be needed?
Looking at T31 RFI, I thought RN was thinking a Frigate Standard hull is needed and hence T31 was required. If true, "using River B2 to counter fast boat swarms" will not be a good idea. This is my main question, and the reason why I am not so strongly pushing for "up-armed River B2".
#Even so, River B2 in the gulf can have good "place to live", because there are many types of ships (mostly merchant vessels) steaming in the Gulf and variety of tasks will be there. In short, if a MCMV can do some types of patrol, surely River B2 can.
Another idea of arming OPVs with "a 57mm gun" will be for deplomatic reasons, "show the flag". That is one idea, very different from the above one.
Ref *1: On hull standard.
If we look around the web, we can find merchant-ship like hull based OPVs like Damen OPVs (see
https://www.damen.com/catalogue/defence ... curity/opv) and Vard-7 series. The Malta-navy OPV (Babcock lost its bid, and directly causing the closure of Appledore) looks the same.
Another class "looks" like a more a corvette like hull, like River B2, Holland, and BAM