Fishing over Rough ground can be very expensive regarding weights and terminal tackle. The only real soultion that helps is using "the Rotten Bottom rig". This enables the weight/sinker to be lost if you get a fish, or get stuck reeling in. The only other suggestion if you don't want to go down this route is to collect stones etc that you can drill and tie on the end of your rig, drilling them makes it easier to attatch as tying the line around a rock is not the most secure method for casting and it can be dangerous if the rock comes loose during casting as the rock will be travelling at a fair MPH. If you are fishing very rough ground I would suggest using a sinker/weight without any wires or grips as the ones with grips are meant for sandy bottoms etc and not rock, they will get stuck very easily.
http://www.gofishing.co.uk/Sea-Angler/Se...ottom-rig/
Here's a simplified version of the rotton bottom rig
http://www.whitbyseaanglers.co.uk/rotten-bottom-rigs