Re: I can't heave to
I use a rope tied across the cockpit that loosely loops around the tiller when I'm steering. If I have to 'lock' the tiller in position, I move the rope loop forward as far as it will go, which makes both sides of the rope taut. It does not get simpler than that. It works even in my dinghy that has a very temperamental steering. In the dinghy, I pee into my bailing scoop. I do not pee in my cockpit in my Mirage - that is low class, and stinky. I use a small bucket and rinse it right away.
As to the hove to problem: if the wind changes a lot and you have a current, hove to in a small boat can be tricky.
Be kind, for everyone you meet is fighting a hard battle.