I keep 'Crackerjack" moored up in the middle of the Tamar, which has a very strong current running through it, and I use 1 long length of braided rope [probably 8' - 9' long], with both ends tied off to a stainless steel swivel shackle on the buoy, and a float on about 3' of rope tied off in the middle of the braided line. I have sleeved the mooring line with 2 bits of see=through plastic pipe, so as to avoid chafe. I then pick up the line and secure it, over the stemhead to a cleat, and then use what's left of the line to secure over the other cleat and back to the buoy, either over the stem head or just over the gunwhale, this second bight is slightly slack, so if the main one lets go, it still has a second to secure it. It is also important to mouse off all the shackle pins etc with tie wraps, they have been known to come loose!

As far as leaving the boat is concerned, I leave the centreboard nearly all the way down as well as the rudders. This stops the constant swinging that a Mac will always do, finally I have bought some flappy plastic flags that builders use to isolate their working area, and string them fore and aft to stop the seagulls cr*pping all over the deck and sail covers etc.

Best of luck :D