To convert your yacht from slab to single line reefing, you will need to modify your existing reefing system by adding some blocks, sheaves and lines that will allow you to pull down both the outboard and inboard reef cringles with one line. The exact configuration may vary depending on your boom and mast layout, but the general steps are: Attach a block or sheave at the end of the boom that can redirect the reefing line from the outboard cringle to the inboard end of the boom; Attach another block or sheave at the inboard end of the boom that can redirect the reefing line from the boom to the inboard cringle; Attach a block or sheave at the base of the mast that can redirect the reefing line from the inboard cringle to the cockpit; Run a low-stretch rope from the cockpit cleat or winch, through the mast base block, through the inboard cringle, through the boom end block, through the outboard cringle, and back to the cockpit cleat or winch. This will be your single-line reefing line; Remove or disable any existing lines or hardware that were used for slab reefing, such as reefing pennants or hooks. Some tips and considerations for converting to single-line reefing are: Make sure all blocks, sheaves and lines are sized appropriately for your sail area and load; Make sure all blocks, sheaves and lines are aligned properly and run smoothly without any twists or jams; Make sure all blocks, sheaves and lines are secured firmly to the boom, mast and deck using rivets, screws, washers or other suitable fasteners; Make sure you have enough slack in your halyard and topping lift to lower your sail to the desired reef point; Make sure you mark your halyard and reefing line with tape or markers to indicate where to stop for each reef point.