Where are they breaking (they usually break at the welded joint at either end)....
Hand tied is actually stronger... 8mm chord might also help. Hand tied eliminates the welded joint.
Pics of hand-tied and further discussion on link below.... Limited options in hand tied these days though.
You are close to Ocean & Earth, and could buy direct from them, or phone them up for a brief discussion about your problem.
Or ring Balin. They can make hand-tied leashes to suit.
www.seabreeze.com.au/forums/Surfing/Longboarding/a-legrope-that-doesnt-g-break/
