The sailpack/stakpack I made myself is not attached to the boom or the sail. I made it in two pieces that join together underneath the sail with cut-outs for the sail slides on the boom. The sides are attached to the lazy jack lines which go underneath the boom and up the other side. Tightening the lazy jack lines hauls up the sides of the envelope when the sail is flaked. The lines can be loosened or let out to prevent the lazy jacks from interfering with the boom elevation when sailing.
- - Each side is a very long triangle piece of Sunbrella sewn to provide extra cloth as it nears the main mast
. You need to allow for the much larger bulk of flaked sail at the mast
end of the boom. I use velcro and snaps to attach the sides together as they pass under the mainsail
but above the actual boom tube. The top of the stackpak has a long length of CPVC plastic pipe sewn in to minimize sag in the cloth in between lazy jack down lines. I chose CPVC pipe as it is stiffer than the white PVC pipe.
- - I added two horizontal pieces of Sunbrella with a zipper joining them so that I can "zip" the bag closed above the flaked mainsail. The zipper has a long continuous pull line so I can stand at the mast and un-zip the top of the bag or zip it shut later.