In 1977 Dwan was accepted as one of Royal Watermen during the Queen's Jubilee Year. Dwan continued to work as a lighterman, but with severance at the docks, he decided to work for himself and withdrew from lighterage and rowing at the same time. For a while he worked on the building of the Thames Barrier, and then on pleasure boats on the River Thames. He then went into business with Bill Ludgrove and set up their own company Thames Cruises. The business grew and they bought a repair yard at Eel Pie Island. Thames Cruises owned the pleasure boat Marchioness which was sunk with loss of life in the Marchioness disaster when the pleasure boat collided with a dredger ""Bowbelle" in August 1989. The disaster was found by the Marine Accident Investigation Branch to have been caused by the poor visibility from each ship's wheelhouse, the fact that both vessels were using the centre of the river, and that no clear instructions were given to the look-out at the bow of the "Bowbelle". Twelve years later another report by Lord Clarke also blamed poor lookouts on both vessels for the collision and criticised the owners and managers of both vessels for failing to properly instruct and monitor their crews. In 2004 Dwan was appointed Queen's Bargemaster, being responsible for the safety of the Queen when she travelled by water. However in the light of protests because of his involvement with the Marchioness disaster, he resigned.