What is "tuggers"

Usage examples of "tuggers".

The next three days Gareth Swales spent at the harbour, drinking tea and whisky in the office of the harbour master, riding out with the pilot to meet every new vessel as it crossed the bar, jogging in a ricksha along the wharf to speak with the skippers of dhows and Tuggers, rusty old coal-burners and neater, newer oil, burners, or rowing about the harbour in a hired ferry to hail the vessels that lay at anchor in the roads.