Psilander was the son of a clerk in the Royal Wardrobe, who died when Psilander was eleven years old. Raised by a friend of the father, the Stockholm Alderman Johan Hagemeister, he joined the Navy as a clerk in 1687. Two years later Psilander was promoted to Gunner's Mate, and the following year to Gunner. To gain experience, and achieve promotion, Psilander joined the Dutch Navy during the Nine Years' War, serving as rating and petty officer, fighting in the Battle of Beachy Head (1690). Promoted to Sub-Lieutenant in his absence, he returned to Sweden in 1695.