Heaving – to effectively parks the boat at sea. You can heave – to for a lunch break or to weather a storm. Or, as Bernard Moitessier says in his classic The Long Way: “….when you no longer know what to do: come about without touching the sheets, put the helm alee, stretch out in the cockpit, eyes closed, and then see things as they are….”.
How you do it depends to a large extent on your boat and it’s a good idea to practice the manoeuvre so that you can do it when you need to. For most it’s a matter of tightening up to close hauled and then tacking without releasing the jib sheet. Once the jib is aback, let out the main a little and lash the helm alee. Each boat will behave somewhat differently but the principle of setting the helm and main to drive the boat against the backed jib remains – it’s a matter of finding the right balance for your boat and the prevailing conditions.
In storm conditions you’d be down to storm jib and fully reefed main or trysail but you can heave-to with a fuller sail plan if you just want to stop for a contemplate, like Bernard, or to carry out some task which is best done with the boat still.
Hove-to, the boat should lie about 40º or 50º off the wind and forereach slowly. You are underway so need to act accordingly regarding collision avoidance.
One of the more valuable skills in the cruising sailor’s armoury, heaving – to.