Drop jib and come in under mainsail?
Today I was out sailing a 420 in a nice breeze. I was coming back into the dock and thought I would drop the mainsail and come in under jib alone which I have been able to do on a soling. On the 420 though this was pretty much impossible (we lost all our momentum and the boat wouldn't track all that well).
Later, one of the instructors told me that it was only really possible with a following wind. Another instructor sail that as far as dropping one sail goes, start with the jib because most of the power is derived from the mainsail.
I don't know though-- I guess I've read about people running under jib alone so the first instructor's comment makes sens.
The second instructor I wonder about thought because I've read that most power comes from the foresail (at least when its a genoa), so it seems to me that it really depends on the sails one is using.
The best I can figure is this-- we weren't flying a genoa and the jib is pretty small so maybe relative to the current we weren't getting much of a lift.
I wonder though is there some reason why sailing under mainsail alone makes sense in terms of center of effort?
Basically, what is a good general rule for flying only one or the other?