Error in Grog Animated Knots animation?

[xarax]

  Speed is often of the essence.

  I guess you mean the time required to tie and/or to untie a knot. Of course it is - among many other things ! 

  It may be related to the "simplicity" of the knot, if, into this already very vague / ill-defined word, we include characteristics not only of the final form, but also of the tying procedure that leads to it. A complex, in form, knot, may be simple regarding tying ( and vice versa, although this happens rather rarely : the 2-stand Mathew Walker bend, for example, is very simple, in form, but it requires careful dressing, that is, it can not be tied as easily and quickly as less simple knots ).
  The problem is that, even if we suppose that anybody will agree to anybody else, about what is a "simple" and what is a "complex" form, when it comes to a particular tying procedure, we can be sure that the situation will be reversed ! A tying method which will appear rather simple and easy to some people, will look very complicated and hard to some others - because their ability to form mental pictures of objects, and their hand-eye coordination, varies a lot.
   "Speed" sounds like such an easy word, we all understand what it means immediately - but when we realize that "speed" is directly related to "time", about which know no-thing ( and, perhaps, we can not know any-thing... ), we go back to the square one. Should the time required to understand how a knot works, be included in the evaluation of the degree of the "simplicity" of it ? If we calculate the number of hours we spend on thinking, reading, writing and talking to each other about knots, we will conclude that, even if we had been tying the most complex and difficult to tie and untie knots all this time, we would nt had wasted so much time... So, if we take into account that the time we have to live is limited, any knot, however simple, easy and quick to tie, is infinitely more complex than two-three half hitches, and nothing else - whatever this "else" means.
   In the ocean of time, "Speed" should be taken with a bit of salt.
   The essence is not speed, it is time - and, regarding the kingdom of time  "Abandon hope, all ye who enter here ".   

[roo]

What do you consider the most secure bend for lines of different diameter if a) the knot needs to be untied and b)it is OK if the knot has to be cut off?

The Zeppelin Bend (including a double version, etc.) has excellent security for a jam-resistant bend.  I guess it depends on how much rope you want to throw at the problem if you want the most secure bend.  If you're OK with jamming knots, the whole world of fishing knots opens up to you, but the double/triple/etc. fisherman's knot is commonly used in rope where untying doesn't matter, although it's amazing how often people change their mind about not wanting to untie their rope once they find that things are a tad too short or long. 

Does what you select work equally well for all diameters? Does this work in both double braid and nylon (doubt it would work in unsheathed Dyneema)? Can nylon and double braid be combined?

You have to use some judgement on differences in diameter.  Once it becomes hard to draw things up neatly, you may have to think about switching over to hitching solutions.  Material construction differences seldom poses a big challenge.  If you're intent on knotting some of the slicker Dyneema, you may have to resort to a quadruple fisherman's knot or the like. 

By the way, I just love using a Yosemite finish on a bowline.
It would be great to know if the water bowline is better or worse and for what types of lines and diameters. Do you know which is the better of the two? Why did you select the water bowline and not an ordinary bowline with a Yosemite finish?

The Water Bowline is more secure and stable, which is why I feature it.  On the off chance you need something more, you might look at the Monsoon Bowline variant:

http://notableknotindex.webs.com/monsoonbowline.html

[Seaworthy]

Roo, thanks for all the info.

What do you consider the most secure bend for lines of different diameter if a) the knot needs to be untied and b)it is OK if the knot has to be cut off?

......If you're OK with jamming knots, the whole world of fishing knots opens up to you, but the double/triple/etc. fisherman's knot is commonly used in rope where untying doesn't matter, although it's amazing how often people change their mind about not wanting to untie their rope once they find that things are a tad too short or long. 

I didn't think the fishermans could be used if line was significantly different in diameter, as part of the strength depends on the double/triple overhands butting up well against each other.

Does what you select work equally well for all diameters? Does this work in both double braid and nylon (doubt it would work in unsheathed Dyneema)? Can nylon and double braid be combined?

You have to use some judgement on differences in diameter. 

Judgement seems to be all we have at the moment, rather than solid information.

What do you personally use if you are pushed for time and need to use a simple bend to join double braided polyester and the diameter of the thinner line is, say, 1/4 or ⅓ or 1/2 or ⅔ or 3/4 of the thicker?

If you have more time and can tie a Zeppelin or double Z, what diameter differences is it effective for? Will it still work for 1/4 or ⅓ ?

These are the burning questions .

On the off chance you need something more, you might look at the Monsoon Bowline variant:
http://notableknotindex.webs.com/monsoonbowline.html

Not familiar with this one. Will have a play with it. Thanks for the link (easier than trying to follow written instructions ).