Jeff,
<br>Let me clarify a few things first. The standard barber hauler on a Hobie 20 constists of a pivot block fixed to the outboard ends of the forward cross beam (you knew that) The jibe blocks attach to a cable, the cable runs accoss the tramp under what I think you refered to as the tramp cover. That cable is secured to the hull via a car the runs in the same track the hold the tramp itself. You are asking where those two cars should be located fore and aft. The answer really depends on a number of variables, but your goal is to get the jibe telltales to "break" evenly. When sailing the weather pinch the boat up a bit, if the top inside tale luffs first the cars should move forward, if the bottom inside tale luffs first the car should move backward.
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<br>If you wish to set your boat up relative to other boats you should pay attention to you mast rake. More mast rake requires the jibe blocks and cars to be moved forward. Also pay attention to the age/type of tramp you have compared to others. The cover on newer tramps is further forward then older tramps.
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<br>My suggestion if you are new to sailing. If the boat is used chances are the previous owner set them where they need to be. If the boat is new your dealer should have been able to set the boat up reasonably well. So leave them where they are and just go sailing. If you season is over like it is for so many of us I guess you will just have to read aboat it.<br><br>