We also referred to those on surface ships as being 'skimmers'

The biggest boats I served on were the repeat Valiant SSN's, also served in a couple of SSK's (conventional boats-deisal electric. The smallest boat I ever went on was a deep sea recovery submarine, designed to rescue crew from a downed boat.

Tiny, cramped and very 'cosy'.

Largest sailing ship I ever crewed was the Winston Churchill and the smallest a tiny Drascombe lugger which a friend persuaded me to go sailing across the Solent in mid-winter just to have a beer in Ryde. Stupid idea as it was bitter cold, blowing a bastard and the lugger was open to all weather apart from a sort of dog house affair in the bows.