in a single line system is move the friction points to a place better managed. The simplest system is one that starts at the boom end, up through the clew cringle, back to the boom and forward, up through the tack cringle, and thence to the cockpit. The difficulty in this system is that the friction at the tack cringle must be overcome to put any tension on the clew. With a shuttle block in between, you have only the friction of a free rolling block rather than a sharp turn through a reefing cringle to tension the clew. If the tack is slow at coming down due to friction, the clew is unaffected.

My system is a little different, but requires a fairly low aspect main (or shallow reefs). The line dead ends at the gooseneck, up through the tack cringle, down to the boom and aft through the shuttle block, back forward to the gooseneck and then back to the cockpit. From the shuttle block there is a single line running out the sheave box and to the clew cringle. The advantage is less line banging around the leach and no clew block (also less friction in the clew system). Your reef can only be as deep and the boom is long however. This has worked well, no more friction than a standard 2 line setup and once the position of the lines is set properly the sail sets well.

The graphic shows my original attempt with the line dead ending on the tack cringle. This didn't work well as there is 2x tension on the clew and over time this worked the foot aft, even though the required tension on the tack is modest. Currently the line continues through the tack clew and is dead ended at the gooseneck.

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