Re: I can't heave to
I wouldn't expect to be able to let go of the tiller when heaving to. You will probably have to lash the tiller to leeward (so the boat is trying to head up). The mechanism is: backwinded jib tries to force the bow down, tiller tries to head the boat up. From there it's a matter of finding the balance point. Adjust the main until you find it.
I second those who recommend a tillerpilot. If that's not in your future, get a tiller tamer, or make one on your own- it's a simple device.
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio