I think anyway. I believe I have described it in the past, but to review: the sheet starts on one side (say the port winch) goes up along the cabin trunk, up to the gooseneck, back on the boom to about 3/4, down to the portside hand rail, back to the boom, aft through a sheet stopper, turns 180 degrees around a foot block, the forward in a mirror image of the port side ending on the starboard coaming winch. With the sheet stoppers open, this makes a 4 part bridle type sheet tackle, double ended or adjustable on either side. However when the sheet stoppers are closed, they prevent movement of the line through the 180 turn at the end of the boom effectively dead ending it, and the system converts to 2 independent two part sheets, port and starboard.

The theory behind this was that since the sheet is not expected to provide any leach load (the vang does that always) I didn't need more than 2 parts, the two independent sheets let me positively locate the boom (at least near the middle) which you cannot do with other arrangements. I figured I would use the 4 part bridle mode when running off to keep from having to tend two sheets, or keep from having a very slack lazy sheet pulling in for a jibe. When beating, you can get each sheet set correctly, then just turn the wheel to tack: the new lazy sheet goes slack and the new windward sheet takes over.

It has worked in practice a bit different than I might have supposed, but still better. Beating, the boat is closer winded than I had hoped, so I cannot really get the boom in far enough using the 4 part mode, and always close the stoppers. The windward sheet trims the boom to the right position. When bearing away (if I remember!) I release the sheet stoppers and go to 4 part mode. This keeps tension in all the lines, and it turns out I need the power to crank in for a jibe. Both sheet winches are powered, so if single handing and lazy, I crank each side in alternately (or push both buttons together if the wind is lighter). When the boom is within reach over the rail, I close the stoppers and continue to crank the windward sheet, keeping a little tension in both. The boom then comes across completely controlled by the two sheets, in conjunction with the fully battened main, jibes are quite lacking in drama, even in 25 - 30 knots with a full (960 square foot!) main. I had originally thought that the 4 part mode would be too slow when reaching or running, and would just be a necessary evil for convenience, but I have found the rig so powerful I am glad to have it.

The mizzen has two independent two part sheets, this done to be able to control the mizzen for steering: I can turn around from the helm, and by playing the mizzen sheets back the mizzen either direction by hand (it is only about 220 sq ft). Its pretty easy to brake to a stop and back down under complete control this way. Once a couple of knots of sternway are gathered, I can just pull it one way and cleat, and steer backwards with the rudder. The boat heaves to very nicely on the mizzen as well.

Most of the hardware to accomplish this was custom made. The main boom made use of some pieces of Antal floppy blocks, but the worked very poorly until I redid them (the sheaves are Antal stock). The cheeks had to be extended to get them to align correctly, all the mounting stuff was CNC machined:

The rail block is integrated into the hand rail. The block pivots on aluminum bronze bushings in the little pedestals. It might look dainty, but I think they are strong enough, blind thru-bolted to a carbon band laminated into the cabintop. Sheaves are Harken Big Boat sheaves, the rest is custom made. I really need to make a nicer looking bolt for the sheave:

The turning blocks up front required some thought because as the mast rotates, the leads all change. The angles are a compromise of leads between port and starboard jibe. I used Antal Tulip sheaves which accommodate some amount of unfair lead, the rest is custom. For the cheeks I matched the style of the other Harken blocks (the one foot block lower left is the only stock piece in the photo besides the Schaefer cleats). Turning blocks and organizers are custom made, even the rail chock was investment cast in 316 SS to fit from a 3D computer model I designed: