With one exception, you must hold and sail on an MMC endorsement of Mate (Pilot) of Towing Vessels before you can qualify for Master of Towing. The exception is holding a MMC endorsement as Master 500 tons or higher. For mariners working on towing vessel there are two paths to mate of Towing; Apprentice Mate (Steersman) and Mate 500 ton or higher. The path that is best for you depends on how much sea service experience you have.
If you are just starting your towing vessel career than the Apprentice Mate (Steersman) path is likely the best path. The big advantage of the Apprentice Mate is that all the exams may be satisfied by taking an approved course, The sea service requirements for the Apprentice Mate is 540 total days, that include 360 days on towing vessels. The other 180 days can come from experience on any type or size of vessel; such as a skiff power by an outboard, a ski-boat, or any other recreational or commercial craft. Once you have the sea service experience you can apply for and complete the classes for the Apprentice Mate. To qualify for Mate (Pilot) of Towing you need to gain another 360 days of experience on towing vessels, while holding the Apprentice Mate endorsement, and complete the TOAR (Towing Officer Assessment Record) and a Radar Observer Course. This path requires two-years (720 days) of total experience on towing vessels to get the Mate (Pilot) of Towing endorsement.
If you have been a career deckhand with years and years of experience on towing vessels than the faster path may be for you to get the Mate 500 ton endorsement. To qualify for Mate 500 tons you will need to document two-years (720 days) of total experience that includes one-year (360 days) on vessels greater than 50 tons, and 90 days as Able Seaman (AB) on vessels greater than 50 tons while holding an endorsement as AB. In addition to documenting this sea service experience the mariner must also complete an Advanced Fire Fighting course, and a Radar Observer course. Once these requirements have been met the mariner may apply for the Mate 500 ton endorsement. Upon approval of the application the mariner will receive a letter stating that they are approved to test and have one year to complete the exams. Preparing to test at a Coast Guard Regional Exam Center (REC) generally takes from a few weeks to a few months of license prep, depending on the individual. A mariner holding a Mate 500 ton endorsement, and having 30 days of training and observation on towing vessels, and a completed TOAR may sail as mate on any towing vessel within the restrictions on the Mate endorsement. This path requires two-years of total sea service experience, with only 30 days experience on towing vessels.