riverman wrote:

I found that, unless I actually tied off at the bow ring of the boat,
the
boat was free to slide back and forth along the rope. I tie off at
the bow
ring with a bowline, run the line down to one end of the bumper,
through
that tie down point, across to the other end, then back up to the
bow.

And then when you tie the stern probably the best way is with a
trucker's hitch. The coolest knot ever. Be careful though, you can
break stuff with a trucker's hitch by tightening it too much. It's like
using a pulley.