True. That was the basis of Swansea and of Portishead and of Penarth. But then if you bear in mind the scale of costs of harbour wall and lock gate maintenance let alone dredging, a few boats paying £2kpa will never be enough revenue. God knows what will happen in Cardiff when the barrage facilities become old enough to need serious maintenance / refurb.I think that the Marine Group are also into property development, and a prime site around a harbour has a great attraction in the long run for major profits when developed, acquiring the harbour and surrounding area is an easy long term goal for a developer, and if it means occasionally dredging a harbour (usually rather in efficiently) and providing a few baiting facilities , then that’s just one of the initial costs that will be recovered eventually.
Watchet is another example of the same issue. No way can mooring fees for the few boats in there cover the cost of staff plus the regular dredging that is needed, let alone a profit for the operator.