Hmmm, maybe a hoist stop would help... Nope, sailed yesterday and it happened again. To be straight up I got really fed up with the slug issue long ago...
My two new mainsails have different set ups, one with a slug and the other with a grommet ..? See photo, and solutions...
Solution is too simple, fasten a line / or velcro strap around spar and allow the tack to travel.... Bonus of travel is when sail eased for down wind you auto ease outhaul by an 1/2 thickness of spar... about an 1" or so..
Secondary issue, around spar is just that.... yes, I've put this solution around the cunningham and pole launcher at the same time... just slow...