From 1912 to 1940 he served as Second Officer on many ships including the Baron Ardrossan, Canford Chine, Carthusian, Dumfries, Turcoman, Stancroft and Llanishan. The Stancroft was a blockade runner during the Spanish Civil War, and as David remarked she had no wireless facility, so if anything was to go wrong then they were on their own. At one time after discharging a cargo of coal at Santander this vessel took on board 2000 refugees for transportation to Nantes in France. They had hardly got under way when one of Franco's warships, the Admiral Cervantes, stopped the vessel and despite knowing that there were refugees on board, inexplicably, and to the crews relief, allowed the Stancroft to proceed. On one occasion whilst ashore in Barcelona David was caught in a bombardment resulting in the city's lights going out making it very dangerous and difficult finding his way back to the ship. In another incident in Valencia there was an air-raid and a bomb dropped 50 yards form the Stancroft shaking the ship from stem to stern like a toy. This was a very narrow miss but a nearby Greek vessel was hit with the loss of 8 lives. By the end of 1937 David was happy to end his involvement in the Spanish Civil War. His next ship the Llanishan, ran timber from Archangel to Cape Town where the newspaper, the Cape Times, featured a story on David and his experiences in Spain. After retiring from sea he took up stone engraving.