Also called the Taut-line hitch, Adjustable hitch, Rigger's hitch, Tent-line hitch, and Tent hitch, the Midshipman's Hitch is an excellent knot to create an adjustable loop at the end of a rope. The knot can be slid up and down the standing line to increase or decrease the size of the loop (and thus the length and/or tightness of the standing line) but when load is applied the knot holds securely.
The Midshipman’s Hitch Knot is relatively easy to tie or untie even while holding a load. Watch the video for a breakdown of the steps.
Here are a list of typical uses:
- Securing tent lines
- Used by arborists while climbing trees
- Tying down aircraft
- Creating adjustable moorings in tidal areas
- Secure loads on vehicles
It was even used by astronauts during the second Space Shuttle mission to repair the Hubble Space Telescope. 
In this tutorial we used 1/4" Nylon Utility Rope. It's a great option on or around the water because it floats and holds up well to the elements.