To get a towing endorsement with any license under 500 ton you have to 1) get an apprentice mate and 2) work on a tug for, I believe, 18 months while holding the apprentice mate and 3) complete a toar. With 24 months time on deck you can get a 500 ton license and a toar. Not many deckhands get their shit together in there first six months and get their apprentice mate, which for many requires them to shell out money for school to do so. Therefore, it is faster and easier to get a 500 ton and a toar as your first towing license.