My standard is the 1-2-3 boatlengths using fingers. When I think we're really close to the line, maybe a 1/2 to a 1/4-length off, I'll use a pinching signal, meaning we're tight to the line. Swinging through, is another one, as in when the bow is clear to swing past a transom. If it's not, I'll pat my head, and once it is I'll bring my hand down, and they know it's clear to swing. Hold is a closed fist. If I want them to go back to pace build I'll use a winding motion [with pointer finger]. The faster I winding, the faster the boatspeed. Slow down, is a hand in the air, kind of like a calm-down movement.