Dutchman lines
Rich - after reading your post I have a few ideas. First off, I've got an OEM Dutchman on our boat and it was one of the early models from 1988. The vertical lines are essentially small diameter lifelines, the vinyl coated type with stainless steel cable inside while the newer models are, I believe, monofilament.
First, it must be set up exactly right. Each year I go through a setup and adjustment and I usually don't get it right. Even after 16 years! During the season I usually make one or more adjustments. Contrary to what the Dutchman literature claims, I somehow can't get my main to take a "set" and drop neatly. After dropping I always have to straighten all of the flakes from luff to leach, and often the flakes fall on the wrong side of the boom requiring the sail be pulled from one side to the other. If I could only get this thing adjusted right I think it would work as advertised.
Since your sail is quite a bit larger and heavier than mine, I suspect the little details are more important. Okay, that said, I take our sails off every season (last year was the first time I didn't and I regret that) so, like you, setting them up the next season is always a bit of a guessing game. One of these days I'm going to remember to bring a plastic marking pen along, but everybody knows, as you get older that becomes harder to do.
With regard to flaking, I've got pretty much the same issue you have. After reading this, though, I think the part of the problem may be with tightening the topping lift before dropping the sale. Maybe, instead, it should be loosened??? This way the vertical lines would be tighter and the sail would tend to stay on target instead of sliding off to one side. What do you think of that idea?
With the plastic coated lines it is somewhat easy to see where the clamps were the previous year so I kinda wing the clamping point based on that. I replaced the lines a few years ago and they are a little longer than what they should be because I was going to shorten them after using them for a bit. Never got around to it though. Just try to coil the end up in the bottom pocket but that's hard to do. Just not enough time in the day to do everything.
Second, the plastic disks that are snapped and glued together on the sail don't stay attached. Almost every year I have to replace one or more or re-attach if possible. These disks are $20 each and they are a total PITA. When I had Sailcare service my sails last winter, they found a number of them loose and suggested that instead of replacing them (for $200-300) that I have simple reinforced grommets installed for the control lines to run through the sail. After a year of use, I find that the grommets are a much better solution than the disks. I wish I had Sailcare remove and replace all of the disks with grommets because I now have at least one more that is loose.
The original system used a short strip of white webbing with a hot-knifed slit. When I bought new sails I thought about changing it but after consideration decided to stay with the same system. For me, this works really well and there has never been an issue. Nothing to come apart and will wear forever.
Edit: One thing on my To-Do list is to mark the flakes at the mast with red and green tape. I picked up some red and green tape, same kind as draft tape, from the sail loft a few years back with the intention of putting a small piece on the outside of the flake along the bolt rope to aid in identification if the flake was in the proper direction. I'll try to remember to do this in the spring. I have an out, though, because I should wait until it isn't raining so that might not be until July or August? Wait a minute,… I'll be out sailing then!
Life is too short and its hell if there is nothing on the To-Do list to do.
