It depends, as I said earlier, on whether you categorise warships on size (US Navy) or function (RN). If you are into size it goes Patrol craft-corvette-frigate-destroyer. The fact that the US navy no longer has any corvettes is because they dont see any need for such a small surface combatant. Foreign navies, particularly those that type on function, still do. There are plenty of 1000 ton plus ocean going patrol craft about. The French still use corvettes, allegedly to police their vast colonial empire (??)
There are plenty of 1000 ton plus ocean going patrol craft about.
There are a lot of ocean going vessels well under 1000 tons. The US Army has a fleet under 800 tons. If coastal patrol craft are included why not include armed Boston whalers and ridged inflatables? I served on an ocean tugboat with a Boston whaler work boat - and we used it in the ocean. The LCUs I sailed on spent a lot of time on open ocean runs. I even ran a Mike 8 between Japan and Okinawa, a few times during typhoons.