Navigation authorities gather information and issue safety bulletins and reports of incidents.
CRT have a section on their web site for reporting; Click here. Alternatively you can call and give details of the incident to 0303 040 4040
The Broads Authority also have a section on their web site. click here
One other is PLA, and their reports can be read here: click here
BSS also issue summaries of incidents. The summary for 2012 can be seen here: click here
The Marine Accident Investigation Branch (MAIB) provide reports on all fatalities and other significant events. There reports can be seen here