I want to talk you about how I've changed the main sail sheet circuit on my boat, a Dufor 40. I intentionally say that I've made a change rather an improvement because some would argue that it was best as it was before. I obviously think it's better now because if better fits my needs, but I understand if it's the best for everybody.
As you may know, the Dufour 40 has the main sheet traveller right in front of the helm pedestal, and the sheet is trimmed through a 6:1 blocks system. The sheet than run along the boom and ends up on a winch on the side of the companionway.
It's perfect when have a crew but it's not when you are solo because, to trim the main sail, you have to leave the helm and move in front of the pedestal or to the companionway. Long way...
The admiral cup setup is a better alternative as I can trim the sail using the winches at the sides of the helm. The problem is that the Dufour 40 have just 4 winches instead of 6 . Theoretically I can add two more, but they would be far from the helm, too forward, to be in reach from the helm. Having two winches dedicated to the main sail and two for the job sheets was not an option (let alone the cost).
I decided then to use the windward winch for the mainsail and the leeward for the jib. The problem now is that with the admiral cup setup the mainsail sheet runs from one side of the boat to the other and needs to be stopped on the leeward side to work. When you have dedicated winches it all works fine as the two ends of the sheets are one on the port side winch and the the other on starboard side, but when you have shared winches the leeward side must be dedicated to the jib sheet.
I added a stopper per side to solve the problem so, when I tack, I first close the stopper on the windward side and free the winch. I then put the jib sheet on the windward winch (now free) ready to tack. After completing the maneuver I have the winch that was leeward now windward free of the jib sheet so I can put the mainsail sheet on.
The mainsail sheet didn't move because it was stopped on both sides. Once the sheet is safely on the windward winch I can open the stopper.