I use a piece of 3mm dyneema ....
Does it chew into the dagger well rim? You must have some sort of reinforcement/tape? Whereas webbing probably distributes the pressure and avoid "flossing" out your boat.
Use uncoated spec line. This will be slick enough to not do any damage to gel or paint. Polyester jackets will wear a grove in just a few pulls.
Also note you can not raise the boards while they are under load
