Hi Claire,
Cannot help on the researcher I’m afraid. However, the RNR was jointly managed by the Admiralty and the Board of Trade – records for both are in the NA Kew see for e.g. BT 164
For info on shipwrecks have a look at ‘Lloyds List’ – an insurance trade journal that covers shipwrecks, comings, goings, weather, etc. Many of these are available online from various sources e.g. early ones HERE
and later ones HERE e.g. sample edition 1 Jan 1868
From personal experience researching NA Kew RN records (ADM files for a Napoleonic War era RN officer) it is not very difficult but takes time to understand Kew’shierarchical filing system. It also is easy to miss something and often quite costly, as some large files have to be purchased/copied just to get at a one-page entry. Try some basic searching yourself first and pass the clues to a ‘local’ familiar with BT records. Best of luck with it.