The effects of wash produced varies from craft to craft, small boats can and do produce a lot of wash.
The speed limit is well posted in most area's, what concerns me is that the 6 mph limit at Brundall Gardens ought to be 5 mph with those boats moored on the riverside, when I am training I mention to all new owners that they should slow down for these boats.
After all the years we have been hiring on the canals I am well aware of being moored on the bank side and being thrown all over the place with boats passing at normal speed,
Regards
Alan