What's the best/easiest way to put a split tail on a mainsheet? I have an 8mm sheet and would ideally like to have this end in two 3 or 4mm lines. I've tried knotting a line through the mainsheet, and this works OK, but the knot doesn't last very long as it gets pulled through the traveller.

Any suggestions? I have absolutely no idea when it comes to splicing/sewing ropes.

Paul