Slocum's boat, Spray, could be set up to self steer. She wasn't a great sailor but was able to be balanced out with various sail combinations to sail on her own. Unfortunately Spray reached a point of negative stability at a very shallow angle of heel according to Chapelle who did an analysis of the design from what was known about the boat. Only Slocum's sailing ability got him as far as he did with Spray. Apparently his luck ran out