but our anchor rode is 80' of 5/8" brait. When tied to a dock, the painter works well, but we use the anchor rode when on a beach.

One thing I think is very important is that the dinghy painter floats. That way it won't go under your boat and wrap in the prop or scrub off your bottom paint. Bridle rope (the horsey kind sold in hardware stores) works perfectly for this and lasts a long time. Ours is getting very old and we just bought some of New England Ropes Dinghy Towline, which is a double braid containing a polypropylene core with a nylon cover.

Mark