I think this guide is pretty accurate, and the only one I know of:
https://foghmarine.com/hobie-21se-line-guide.htmlI can also measure mine to validate as she's not quite put up for the winter .
Looks like there may be yet one more sail before 2022 in her!
I second Bill's comment - add a Johnson/hyfield lever for extending shrouds and put an extra length in there so you can get your H21 over-center if she goes capsize. I mean, while you're doing it... The correct way to do it is to get the shroud levers from your outlet and make the eye-to-eye length with the levers in-hand. I ended up measuring and subtracting the levers from the total shroud length and it worked out great. Also makes it VERY easy to adjust shroud tension before sailing.
Chuck