Quite correct and they made one of wood too, think it was number one that went to Guernsey, the cox got a gold medal aboard her for daring do one nasty night many years ago, She is still kicking around somewhere being used as a private vessel.
Yep having helmed several Arun's can atest to their ability in the lumpy stuff, I'd go far as to say probably better than the Severn and Trent when the going gets really sticky, certainly the Trent which is a bit of a bouncy machine. They did a big engined version for trials before the Trent and Severn and she regularly clocked more than 25 knts so just as quick as the new boats.
To be honest in my view they should have redeveloped the Arun with bigger motors, better visability (flippin horrible inside to see out of) and would have had a brilliant rescue vessel for a fraction of the money spent on the development of the new boats. On the otherhand the new boats carry so much techy stuff they probably felt it better to start from scratch.
The new Tarmar , now that is a cracking machine, really nice in the big stuff, easy peasy to handle and monsterously powerful, you could bin all other boats in the fleet and just have the Tarmar, does everything from boat house boat, afloat boat, inshore and all weather, would simplify the engineering dept's and the store sand spares departments.
The design for the CCG 47' Cape Class boats was purchased by the Canadian Government from Textron Marine Systems, who developed the design based on a preliminary design by USCG Naval Architects. The project (replacing the old USCG 44'MLB) started in about 1984 and the first Textron boats hit the water for testing in about 1989-90. Canada built most of ours in the early 2000's I think. Ours are modified from the US version, mostly in updated equipment and a change from GM to Caterpillar engines. I have a faint idea we changed from vee-drives to straight shaft as well, but that needs more research.
When they started the USCG was looking closely at the RNLI's 52 Arun, 47 Tyne, and 50 Thames, as well as the Norwegian Olav 5 and Skomvaer III. I think most of those are round bottom fiberglass boats whereas the Textron/USCG design is a vee-bottom aluminum boat.