The club that you passed was Avon Sailing Club.
You probably noticed that is was on the Severn. To find Severn Sailing Club, you need to look on the Avon.
When you meet sailing dinghies with a narrowboat, it's best to ignore the colregs and take a pragmatic approach.
Firstly, if they are racing, collisions with narrowboats do nothing to improve speed, and can damage the dinghy.
Secondly, a sailing dinghy is several levels of magnitude more manoeuvrable than a narrrowboat. By zig-zagging around, you are actually making it harder for the dinghy sailors, not easier.
By far the best approach is to move over as far as possible to the right, and just motor though slowly at a constant speed.