This version of the slip knot is basically a uni knot tied with rope and with just one or two wraps around the double line. It does the trick and is easy to tie.
Watch the demonstration diagram & follow these steps.
How to tie the slip knot for boating:
1.Run line through object or around object and double back parallel to the standing line. Make a loop by laying tag end over the double line.
2. Make one or two turns with the tag end around the double line and through the loop.
3. Pull tag ends snug up the turns.
4. Knot can now be slipped to tighten onto object if desired.