we are thinking about getting a square top mainsail and therefore splitting the backstay would become necessary. No problem until here.
The difficulty is that we have a below deck setup which we would want to keep, because it keeps the cockpit clean. Right now we have a block attached to the backstay end ca. 2m above the transom and from there two ends going through turning blocks in the transom below deck where additional 3:1 purchases are located. The backstay has a flicker at the top so the mainsail can pass through easily when eased.
Now for the split version it has to be setup in a way that the leeward side can be eased all the way to the mast which requires a longer adjusting range (transom to mast=4,5m, mast height =12m so ca. 3,7m). IMO we need a coarse and fine tune (winch is not an option) which have to be located below deck, because we cannot put additional fttings on the transom (reaching the transom from inside is impossible) or change the turning blocks.
The distance from transom to the cleats on the cockpit floor (approx. 2m) limits the adjusting range if you put purchases in there. The idea I came up with was to put in a 1:2 coarse tune doubling available range and a 6:1 fine tune on each side (see drawing).
What do you think about the system. Any mistakes in my ideas? Will the cleat in the cockpit be able to hold it?