The following is a quoted from the Acquisitions Directorate (CG-9) web site. The boats referred to here do not seem to be the same as the Over the Horizon Boats currently being used on Bertholf class NSCs and Webber class FRCs discussed on the linked page. An earlier release available here outlines the Request for Proposal, indicating an intent to replace an existing fleet of 36 boats, with total procurement of up to 46 boats over the next five years.
The Coast Guard awarded a firm-fixed price indefinite delivery, indefinite quantity contract Aug. 30, to MetalCraft Marine U.S. Incorporated of Cape Vincent, New York, for a fleet of cutter boats-large (CB-L).
The contract has a maximum value of $20 million and allows for the acquisition of more boats over an ordering period of five years. The initial delivery order for two CB-Ls, trailers, delivery, training and associated logistics documentation was placed for approximately $590,000.
The CB-L will replace the current fleet of 24-foot cutter boats in service onboard 210-foot medium endurance cutters, 225-foot seagoing buoy tenders, and Coast Guard Cutters Alex Haley and Mackinaw. The boats will support operations on the East, West, and Gulf Coasts, as well as in Hawaii, Guam and Alaska.
“We are very excited about getting this asset out to the fleet,” said Cmdr. David Obermeier, deputy program manager for boats acquisition. “A single boat class for multiple cutter classes will provide enhanced operational flexibility.”
For more information: Cutter Boats program page
Chuck Hill's CG Blog 
Good info. For the record, the cutter classes are not named after their lead hull but instead Sentinel-class (FRC) and Legend-class (NSC), respectively.
Sentinel, RFC, and NSC were program names when we did not have a name of first in class. Naming the class for the first ship of the class may not be CG policy, but it is an internationally accepted convention. Plus WMSL and WMSM are particularly inappropriate (https://chuckhillscgblog.net/2013/08/19/ship-type-designations/) so I am doing my bit to be both understandable and in some small way to bring the Coast Guard around to a more sensible system of reference. So I will continue to refer to the Bertholf class NSCs (after all we could have more than one class of NSC), the Webber class WPCs, and the Argus class OPCs.
Instead of NSCs and WPCs, why not 418s and 154s?
I’ve some times wondered why not myself, but it does not seem to have been used by anyone.
From the Acquisitions Directorate, they have a photo as well. Given the hull number in the photo, they are apparently 22 feet in length. https://www.dcms.uscg.mil/Our-Organization/Assistant-Commandant-for-Acquisitions-CG-9/Newsroom/Latest-Acquisition-News/Article/1951053/coast-guard-accepts-delivery-of-new-cutter-boats/
The Coast Guard took delivery and accepted the first boat in a new fleet of cutter boats-large (CB-Ls) Aug. 22 in Charleston, South Carolina. The CB-Ls will replace the current fleet of 36 cutter boats that operate aboard the service’s 210-foot medium endurance cutters, 225-foot seagoing buoy tenders, and Coast Guard cutters Alex Haley and Mackinaw.
The service completed testing before acceptance and delivery and will conduct additional testing – interface test and evaluation and the operational test and evaluation – over the next few months to verify suitability and effectiveness before moving to full production.
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