The faces of the members of a ship's crew are mere spots, a few strokes with a dry brush conjure up the fine-meshed net of a fishing vessel and his fluffy clouds are done with a few coarse strokes. Paintings with historical ships and backgrounds required research. In order to paint as true to life as possible, Sterkenburg frequently consulted his extensive collection of books on historical and maritime matters. He possessed a photographic memory, enabling him to depict a certain ship twice and from completely different angles. In order to depict modern ships correctly he used a camera on-site but only used the details, never directly copying photos. One of his principles was that he could not paint the correct light, sky- and water colour before he had actually visited the places which formed the background in his paintings. This resulted in study trips to ports around the world.