what critical ropes knots often used outdoors ? There are so many rope knots that I can't recall of them.

Can someone list some of most important that can save lives?

Bowline, with the variation of bowline on a bight. Non slip knot, can be used to raise/lower a person.

Clove hitch, used for tying things up, as in bundles, a tent line to a tree. Variation is clove hitch with quick release.

Square knot, used to join two like ropes together.

Taut line hitch, used on tents as you can release or add tension w/o retying the knot.

Overhand knot. The most simple.

I'd call these the big 5.

you might get a Special Forces or Ranger to show you how to tie a Swiss seat from a section of kernmantle, for emergency rappelling

I second the taut line hitch. I just got home today from camping with my family and I used taut line hitch, guy line hitch, overhand knot, clove hitch, square lashing, and I attempted a rolling hitch (didn't work, though).

-Jason

The bowline knot is the classic climbing knot and it indeed is highly useful, but even better, and now more common in use by climbers, is the figure 8 and a closely allied knot, the "figure 9."

The clove hitch is an extraordinarily useful and versatile knot. Very easy to learn and apply.

The square knot is way overrated. It is best employed to tie shoelaces and nothing more critical. The fisherman's knot (or triple fishermans) is much more secure for joining two ropes; the water knot is good for joining webbing.

For climbers, the prussik (or several similar) is well worth knowing. It is very closely related to the taut line hitch

One reason there are so many knots is that different activities require different means of joining and manipulating rope. There are considerable differences between what is employed in climbing compared with boating. So, what specific use are you considering? That determines the knots you should learn.

By learning, I mean the ability to tie the knot in a dark shower with your eyes closed and the cold water running full. It is better to learn a few knots well than a whole bunch half way.

If you are tying knots for any serious purpose, they should be backed up - typically with two half hitches.

Very dangerous to use a square knot as a bend. A square knot is a binding knot only.

My basic essentials would be:

Round Turn and Two Half Hitches
Figure Eight
Hunters Bend or Zeppelin Bend (closely related)
Bowline
Constrictor Knot
Tautline Hitch
Square Knot

Other very handy knots:

Ashley's Stopper Knot
Double Fisherman's Bend
Angler's Loop
Alpine Butterfly
Ground Line Hitch
Simple Simon (under)

If you end up stuck with that ultra cheap super-hard, tough-to-bend three-strand-twisted slippery nylon junk rope, in order to get a knot to hold you need something more obscure like:

Vice Versa
Surgeon's Knot

I with all of these but would add the round turn with two half hitches. As an Infantry and Special Forces veteran, and a Scout Master, if you learn 4 or 5 of the most useful knots and learn to tie them in the dark when it is raining cats and dogs, then you will be able to get through most things.

Doing similar research for another project -- Found the two worst knots: Square and the shoelace knot. Both pretty awful for what they do.

One of the Eagle Scouts from my sons' troupe went on to college and then the US Army. He went to Iraq with his unit. When unpacking and setting up their tents they found that ALL of the little metal guy line tensioner plates (or whatever they are called) were missing. For the entire unit.

Not one person knew what to do. Except him. He showed them how to use the taught line hitch. He was quite the hero!

Craig T.