Can someone explain the need for cross ties? My zipper is under no strain at all.
Paul M
NS30U #211, Sandpiper
Cowichan Bay B.C.
Cross over Lines (COL) are deployed after the sail drops and the zip is closed. At this point the supporting lines are holding up the entire mass but because of the wishbone rig, the lines are also pulling outward with stress on the zipper to port and starboard. A COL is about six to eight inches long and has a snap ring or small shackle on both ends. After the sail is down and the zipper is zipped up, the cross over line is snapped between the two opposite suspending lines. Because the cross over line is shorter than the distance between the two opposing links, it lessens the side load from the zipper. The side load is trying to tear the zipper apart
All of that sound to complicated.
Envision a zipper and then think of the support lines trying to pull the zipper apart. The COL between the two support lines limits amount of side load on the zipper. That is still kind of a mushey explanation of how it works. If it will help, I will take a photo of my cross overs and you will see how the side load is reduced. I keep my COL loose on one side when the sail is up but I keep them attached when ever the sail is down and zipper close. You can make a set and apply it to any stack pack your currently have. Great idea from Butch Garren.
Thanks Ed,
When I laid out the lines on my cover where the support rods would go I left the top panels the width of the distance between the lazy jack lines. The weight is straight down on the lines now with no sideways component so there is no strain on the zipper.
If the panels are narrower I can see the reasoning though. Thanks for the explanation.
Paul M
NS30U #211, Sandpiper
Cowichan Bay, B.C.
Oops, got sent early…never posted pics before This was my solution on Duck Soup.
Having a relatively new sail cover before I saw the Light, I modified my cover to do the job. Note I left the jack lines and bottom closure clips as they were to simplify construction, added three zippers on top, two 10 ft and the aft 5 foot unit giving a space for the 2nd reef clew lines to exit and added lift elastics (from Lee Valley..thanks Persistence) I prevented excess scallops by adding strong shock cords at the aft end to tension the cover to allow choker adjustments
The zipper starts forward at the mast with the shortened mast surround zipper reinforced by two 1" traps sewed onto the sail cover low down to pull up the forward bottom of the sail cover to keep it up for forward vision under sail.
Note the sail cover can be installed after the sail is bent on by using the old clips on the bottom and removed the same way. The gaps between the clips at the bottom provide drainage. An interesting aspect of the design is that wind leakage below the sail blows the cover into a broad u shape and displaces it to windward where it provides great winglet…maybe even adding to sail efficiency. 
And no rods
Note my two trolling motors aft that can push me at 3 knots and the foreward mounted solar panels a la Persistence.
Getting tired of dealing with my old, falling apart, ill fitting sail cover and hoping to make a sail pack over the winter. Enjoying the photos of the various designs. I’m thinking of making one without zippers using straps and velcro for the top closure.
Nice work Dale.
There are lots of right ways to do this and it’s not rocket science at all. I left the bottom twist closures too and yes they do work just as you say. One note about the rods, I really like them for the crisp line the give and they make great handholds when the sail is furled and on centreline.
Paul M
NS30U, Sandpiper
Cowichan Bay, B.C.