chuckmaui said..
I use NP adjustable 24"-30", on 81cm wide foilboard, wide straps spread and wide stance, mastbase at 130cm from front screw of tuttle,
I'm using AFS 95 with f800 and f700 wings, sails from 4.2 to 7.8,
24 length up and cross wind, lengthen to 30 for downwind. I use 28" on my windsurf equip.
I had the same feeling while foiling of the harness line falling out with 28".

Chuckmaui Thank you!, I have the same foil and wing set, I decided to move my boom 2" higher so I could use my Ion vario lines (28-34) but looking at getting shorter adjustable lines, will look at the NP lines, they would cover my high range and should go low enough.

I use these , they can be lengthened and shortened while under way by pulling up on the loop to lengthen, or shorten by pulling down on the triangle pull tab, while hooked in, NP RACE HARNESS LINE 24-30
the other NP straps Travel Vario do not allow changing length while under way.

Put my Ion vario 28-34" lines back on and tested with my 5.8 sail in 18-22 knots the other day. Now I did move the boom up 2", which I believe equals 4" of line length, right? At the minimum line setting of 28", with ends spread apart 4 fingers width, the lines just carried the sail pressure inflight. So at the regular boom height I would need lines that were 4" shorter, so 24". Now the lines worked at 29" for my 8.0 sail at the regular boom position, so adjustable lines that covered 24-29" would be good. But could always move boom up/down 0.5" to effectively shorten/lengthen lines by 1" if needed. Just need to wait for dealers to get harness lines in stock.

Just ordered the Sailworks adjustable harness lines with a V cleat pulley, will see how they work and get back. They swing, and do not have to remove tail to put on.