He painted in oils and watercolors and perfected his skills in graphic arts, especially etchings. Hansen became enamored of creating marine scenes, particularly involving man's relationship with the sea. In 1914 he produced a "Self Portrait". Hansen became extremely active in large Carmel-by-the-Sea art colony. He was not a founder of the Carmel Art Association in 1927, but eventually joined that organization and served as president and on the board of directors. He was the co-founder of the Carmel Art Institute in 1938. In the early 1920s Hansen lived near the Stevenson House, and he often entertained other artists, including members of the Society of Six. By this time Hansen was not only one of the most well known California artists, but arguably the best teacher of the era. A typical Painting of his early period in Monterey, "Men of the Sea", illustrates his bond with his subjects. In 1920 he began outdoor lessons for both Clayton Sumner Price and August Francois Gay. E. Charlton Fortune also studied with Hansen. Hansen was also unique in that he had friends in among the avant-garde and conservative artists in Monterey and Carmel. An important work of this period is his "The Salmon Trawlers" (1923), which is in the permanent collection of the Monterey Museum of Art. In the 1930s Hansen's paintings become more intense and use of light more pronounced. One of his masterpieces of this era was "Sardine Barge" circa 1933, which appropriately is in the permanent collection of the Monterey Museum of Art. Later in Monterey Hansen led a group of artists in opposing a plan to remove Fisherman's Wharf as part of a grandiose redevelopment scheme. The wharf was an important subject of their art, besides the fact that Hansen identified with the simple life of a fisherman. These artists were considered a bohemian group, living in the Peters Gate area of Monterey, but amazingly they prevailed against bigger business interests. In 1997, a film "Time Captured in Paintings: The Monterey Legacy" was produced honoring Hansen, along with E. Charlton Fortune, William Frederic Ritschel, Xavier Martinez and others. The film, narrated by actor Jack Lemmon won the Golden Eagle Award from the prestigious CINE for documentary films in 1997.