verb - Draft is to swim close behind, or slightly to the side, usually somewhere between the hips and ankles, of another open water swimmer (or swimmers) in order to take advantage of their slipstream, especially in a race.
The cagey veteran was drafting behind the young swimmer throughout the race.
Middle English draught, act of drawing or pulling, from Old English.
hang on, follow, drag and free ride, swim in the slipstream
noun - Draft is a group of fish.
The swimmers passed over a draft of fish as they jumped off the escort boat.