Having a crew run the mainsheet is an instant go fast idea. I usually have the main in my posession when I sail with Eileen as she is not comfortable enough to know how to play it. We are trying it little by little on practice days but...

I went out a couple of times with a crew that knew how to play the mainsheet and the speed increase is significant.

Downwind the spinnaker is the concern for the sheet tension for the crew. The newest cuts require more tension. We run a double ratchet system so she can hold it easily after the sheeting is done. We turn both on in winds over 15 knots. The best part about the spinnaker cats is when the chute tension is that hard your crew is usually out on the wire and can use her (his) legs to do the pulling.

My girlfriend/crew weighs in at 125lbs and will sail with me in all conditions on our Formula 18.

Later,
Dan