Here’s a society whose owners maintain some fabulous small motor-craft built before the 1970s, including the group shown shown below.
The Classic Motor Boat Association organises rallies at which members show their boats, help each other with restoration projects and generally enjoy their boats, and publishes a members’ magazine each quarter packed with articles and club information.
The site includes information about some of the greatest British motor and speed boats, and I strongly recommend the gallery, which is packed with great photos.