Oh, I didn't answer the wandering thing, did I?
OK, here we go...
Lets go back to boat building before efficient 2/4 stroke petrol/diesel engines and revert to wind power or steam, back in time, several thousand years and more. Boats have been built for centuries with keels, which is generically known as a keelson. This is the main piece of wood selected to support all the bulkheads as well as the bow. The keelson being the major action in which the boat keeps straight whilst under way. This would run the length of the boat/ship and would be known as the keel. This with the incorporation of a rudder would keep the boat in a straight line a slow speeds without constant correction. Most displacement boats have a keel or rudder and those designed to run on the Thames or at low speeds would be the same.
Faster sports boats, planning hulls however don't have keels or rudder and at high speed, corrections are easily made. At low speeds, it takes a lot of course changes to keep them straight, including a Fletcher 19GTS.



