You must establish proper rope handling and knot tying techniques prior to setting up an underwater search pattern. Knowing what knot to use and how to tie it on demand is essential. But your goal must be to become proficient enough to tie the essential knots in zero visibility while wearing gloves in cold water and being under stress. So practice, practice, and then practice some more.
As Underwater Criminal Investigators, there are four knots you need to become proficient with:
2. Sheet Bend
4. Figure 8
These four can be used in the majority of any search pattern you set up. But before we talk about them, let's understand some knot tying terminology:
The RUNNING END or END - The end of the rope or the end of the rope you use to tie the knot
The STANDING PART - The part of the rope that is not actively used in making the knot but which the knot is tied to by the running end.
Note: The instructions for tying these knots are given for right-handed people, so if you're left-handed, just use your left hand when the instructions say right hand, and vice-versa.