Sorry, misunderstood question
You weren't asking about regular trimming. You were asking about a tack. Here's what I do in my 20 footer. Dick's theory of single handed jib handling.1. Get all the trimming done before the jib's under load on the new tack. Slow tacking is good. Overtrim on the jib is fine.2. When single handing, the winches are for the halyards not the sheets. Certainly the winch HANDLE is not for the sheets. That's why I pinch, or linger in the middle of my tack, if the windspeed is making it hard to trim the jib without mechanical advantage.3. Have a system that lets you cleat/uncleat the jibsheets with just one hand. In my case, I've rigged the boat so that the sheets end in a swivelling camcleat, with a winch in line before the camcleat, in case I need it.4. Have a system that lets you lock the tiller for a second or two. Personally, I use a cansail tiller lock. This lets me lock and unlock the tiller as easy and fast as switching a light switch on and off. (Great inexpensive device, highly recommended. You have to get it mail order from Canada: I've not seen it any of the US retailers.)That said, I single-hand tack as follows:Turn into the tack without releasing the jib sheet, and slow down at about the "middle" of the turn. At the moment the jib backwinds, lock the tiller for a SLOW turn.Release the sheet on the (new) upwind side of the boat and trim crazy fast, both hands, on the downwind side - aiming to have the jib trimmed all the way in before the boat's powered again.Cleat the jibsheets.At this point, omplete the tack, ease the jib a bit if needed."Slow", of course, is relative. Although I execute this manoeuver slower than if I had crew, I can do it fast enough that I don't lose a whole lot of boatspeed.