When I first bought Elyse I had real issues with the outhaul line...
The previous owner had 10mm polyester installed.
I changed it to 12mm polyester as per Andersen recommendations.
That was marginally better but still slipped.
Then I changed it to 12mm Kevlar and it hasn't slipped since.
Whether 10mm Kevlar would work as well I don't know.
But as far as I am concerned 12mm Kevlar is the answer ... and it has to be TIGHT !
Elyse SM437 Port Vila