Beats me, but the US Navy has been messing around with something they call a "Littoral Combat Ship" for some years now. It's gotten beyond the paper study phase and we actually have two or three of them at sea right now. They are smallish surface vessels, with claims to awesome top speed, something in excess of 30 knots.
According to Aviation Week the Navy is not satisfied with the program so far and wants to redesigate the class as "frigates". That's an old and honorable name for a warship class, going way back into the days of sail. The name died out in the sail to steam conversion, the steam warships that picked up the sailing frigate duties were called cruisers. The name fell out of use in navies until WWII when it was applied to a new class of small anti submarine vessels. Since then frigate has meant a mini-destroyer. Looks like a destroyer but is smaller and cheaper.
The Littoral Combat Ship idea was born after a number of nasty confrontations with small fast missile boats in the Persian Gulf. The idea was a very fast ship that could run the pesky missile boats down and blow them out of the water. This works in the Persian Gulf where the water is calm and smooth enough to get up to speed. It does not work offshore where you have surf and swell. Trying to drive thru even moderate waves at 45 knots will smash the ship apart in a few minutes.
So, the Navy is talking about dropping the high speed requirement on the new Frigate/ex Littoral Combat Ship class. It reduces the size and weight of the engines, leaving more room on board for all the stuff every captain wants to have more of (rations, ammo, fuel, weapons, etc). Aviation Week speculates that the development of small very effective auto cannon systems has solved the missile boat problem. I doubt that. Was I skippering a Navy ship and the missile boats came after me, I'd order up my helicopter. Chopper is twice as fast as anything on water, and carries 5 inch rockets that will turn anything afloat into kindling wood.
The other discouraging thing in the Aviation Week article, is the total lack of any discussion of mission. What is the frigate/ex littoral combat ship supposed to do? Show the flag? Chase subs? Provide gunfire support to an amphibious landing? Missile aircraft? Escort carriers? Just be cheap enough so we can have a lot of 'em? Not a word about any of this.