Mooring pendant/line length

I moor my boat on a mid-size inland lake at our local yacht club. The club sets the mooring buoys at the start of each sailing season. My mooring pendent (the line which attaches from my bouy to my Scot) needs to be replacede. What is the appropriate length for a mooring pendant/line for a Flying Scot? The one I am replacing was around 10 feet long, but the previous owner tied knots in it to cut its length to around 5 feet. Is there a rule of thumb for pendant lengths?

Some recommend 1.5x the distance from where the line attaches to your boat and the surface of the water as a good length to start with.