Best Stopper Knots for Team Supplied Knots
 

I wanted to make this thread to collect and disseminate information on the stopper knots that teams use to hold their ropes on the field. Inspection of these ropes will be a tumultuous undertaking, and I want to make sure as few teams as possible show up to competition with faulty stopper knots. I've already seen some poor suggestions made on these fora and in team meetings on which stopper knots to use, so I'd like to show some good knots that can fit a variety of situations.
I'd also like to hear what other people are planning to use!

My first suggestion for a stopper knot would be the Ashley Stopper knot. It's easy to tie, easy to inspect and can handle odd shapes in the rope. Also, when tied correctly, the load-bearing face of this knot is symmetrical which should reduce the chances of shifting or swinging when load is applied.

If for some reason you cannot tie the Ashley Stopper knot, another excellent alternative is the Stevedore knot. This is another knot that's easy to inspect and easy to tie, and it holds very well even during cyclic loading. Astute observers will notice that it is very similar to the figure-eight knot, but the Stevedore knot is superior because the shape of the knot is not affected by loading as much as the figure-eight.

If your team is using flat webbing or very slick material, you may have some issues getting the above knots to hold. If that's the case, you can try a Double Overhand knot. Knots based on the overhand knot are considered to be superior for webbing, but that's a point of contention among knot and climbing experts.

The above are my three suggestions for stopper knots. Below I have my suggestions for loops either at the end of the rope for easy grabbing or loops along the length for some other type of climbing.

The most versatile loop (and my personal favorite knot) is the Alpine Butterfly. It is strong, easy to tie, takes up relatively little rope length, and is symmetrical. It can be loaded from either end or the loop, or any combination of the three. It can also be tied in the bight or on the end of a rope. It's also easier to adjust the placement or size of the loop if you need to change your loops in between matches. However, if you need a loop to go on the very end of your rope, a different loop may be necessary.

A great end-rope knot is the Bowline. It has a relatively small profile and is very secure. However, the knot can become loose over time if it's not under load. Also, the tail of the knot runs inside the loop itself. This might cause problems if a team's climbing mechanism grabs onto the tail instead of the knot itself. A way to make the knot more secure and direct the tail out of the way is to use a Yosemite finish on the Bowline. However, make sure you know how to correctly tie and inspect the knot if you use a Yosemite bowline. It's one of those that can really go wrong if tied incorrectly.

If your team is using extremely slick or thin rope and/or webbing, you might need to use an Angler's loop. This end-rope loop can be very difficult to untie after loading, but it's one of the very few knots that can hold reliably in bungee cord or an elastic material.


Sorry for the huge dump of information! I just think that, while in the team's shop and under close observation, a team might climb perfectly every time. But in the heat of competition, when things are getting hectic and every last point is vital, I'd hate for a team to lose because of a faulty knot. I'm sure many teams already have resident knot experts, but for the teams that are planning to just use overhand knots for everything, here's some more detailed information.

EDIT - The monkey's fist was purposefully omitted from the list of stopper knots.

Re: Best Stopper Knots for Team Supplied Knots
 

I'm going to take a guess here and assume that many of you don't know how to tie these knots so I figured I would share with you all a link to a website that has very easy, step-by-step instructions for tying all kinds of knots. It is called Knots by Grogg, and I hope it helps:
http://www.animatedknots.com/

Also, I might be a bit biased becuase of the fact that I sail, but I do think that the bowline and the figure eight knots are superior. Both are good becuase if you should need to retie them or change the location of the knot, they are very easy to untie, but also hold exceptionally well. Additionally, they are fairly easy to learn as compared to some of the other mentioned knots.

Re: Best Stopper Knots for Team Supplied Knots
 

I probably should have linked to Knots by Grogg, so thank you! The website doesn't actually work that well for me using Chrome, so I haven't used it in a while and forgot about it.

I should also mention that my experience with knots comes from Boy Scouts and several years of rock climbing and caving, so I have my own biases. I agree that the Bowline is a reliable and commonly known knot. But I listed the Alpine Butterfly above it for a couple reasons. First off, all these knots are easy to learn, and the Alpine Butterfly is easier to inspect and dress with a glance than the Bowline. I find the Alpine Butterfly to be more consistent and reliable over time, and it takes a smaller profile.
I left the Figure Eight loop out for a reason. It's reliable for end loops and is one of the most commonly known knots, but I think it falls short for these purposes for a couple reasons:

• If teams are using some sort of winch, the loop won't lie flat or conform to the winch as easily as other loops and may cause issues.
• If teams are using webbing or any other rope profile that isn't circular, the loop won't dress as easily and becomes much more difficult to inspect, adjust, or untie after loading.
• I find it an extremely time consuming loop to adjust, especially if you only have a few inches of rope on either end to work with.
• This loop does very strange and sometimes unpredictable things when load is applied to both ends and not the loop or when load is applied on the knot itself and not from the loop. It also can do odd things when load is applied in opposite directions from inside the loop.
• It can jam and become difficult to untie even when loaded solely from the loop.

Re: Best Stopper Knots for Team Supplied Knots
 

I concur with JPB, the figure eight knot is very good at creating a large stop knot (I rock climb), and stays together well. They look similar to the Stevedore Knot, but I'm not sure how much larger the figure-eight knot is compared to it. Guess that's a good place to start.

EDIT: OH! You were talking about knots for the robot to interface with. Our team is using a double overhand for it fits in our hook system.

Re: Best Stopper Knots for Team Supplied Knots
 

While I think John was referring to the Figure Eight loop and not the Figure Eight knot, I'm curious as to why you think the Figure Eight is a better stopper knot than the Stevedore. A Stevedore knot is a Figure Eight knot with an extra turn around the standing end before the working end passes back through. Also, the load bearing face of a Figure Eight can be very asymmetrical, and since the DAVITs will only be supporting the stopper knots on 2-3 sides of the knot at any time, I think symmetrical knots are better for this application.

Re: Best Stopper Knots for Team Supplied Knots
 

True, but I have yet to test either knots. I will try both, and if one works better than the other, than thats the one I will use. Never used a knot like that before, so it will be interesting to see what happens. Perhaps a good idea would be to use multiple knots in very close proximity, or use one knot within another to get the best hold.

Re: Best Stopper Knots for Team Supplied Knots
 

I agree that they are all relatively easy to tie, however I think the alpine butterfly is one one the harder ones mentioned. I don't agree with the inspection point you made because bowlines are extreamly easy to inspect. They all make a uniform shape and it is always clear whether or not it is tied correctly. Also, you said that the figure eight is reliable for end loops, so wouldn't that make it better for this situation? How would someone utilize the sideways loop created by the alpine loop at a point other than the bottom of the rope?

Actually I was referring to the figure eight stopper knot. To be completely honest I have never actually used a stevedore knot. I like the figure eight stopper becuase it holds well, but even after pressure has been applied it is still easy to untie. Granted, in the context of this game I don't think people are going to have to untie their stopper knots, but as I mentioned before I am biased, and the ability to untie knots is essential when sailing.

Re: Best Stopper Knots for Team Supplied Knots
 

I ran some somewhat-less-than-scientific tests several years ago to find the best knot for tying two pieces of same-size string together.

What would you recommend? Sole criterion is breaking strength.

Re: Best Stopper Knots for Team Supplied Knots
 

JPBlacksmiths, the reason your quote is failing is because you're missing a ] on the first quote block.

You should have:
vBulletin really doesn't like missing brackets.

Re: Best Stopper Knots for Team Supplied Knots
 

Off the top of my head, I'd say blood knot or Ashley bend. But a Figure Eight bend is also a good candidate.

In theory, the strongest knot would be the the knot that has enough internal friction that the rope breaks before it slips but reduces the rope's breaking strength by the least amount. And in general, the tighter the turn a rope has to make in a knot, the more strength lost. So following that line of reasoning, the strongest knot is to just wrap the two ropes around each other for a long enough stretch of rope that the friction holding them together is stronger than the rope. Now, this is obviously ridiculous in practice, but I wonder if the concept can be applied to making a 'long' knot. something like a repeated Carrick bend maybe? A single Carrick bend itself is good for wet ropes, but is considered to be a weaker bend. However, the turns in a Carrick bend have relatively large radii and can be repeated until you have enough friction. But I've no idea if this is actually practical.

EDIT - Also, I just noticed the title of the thread. Dang it.

Re: Best Stopper Knots for Team Supplied Knots
 

My concern with the inspection of the bowline comes down to this subtlety. Even people born with ropes in their hands can miss this difference if they don't check closely. In a perfect world, it wouldn't really be an issue, but competitions are not perfect worlds.

If you only consider which knot is stronger and more convenient to use as an end-loop, then yes, the figure eight loop is better. But the Alpine Butterfly has a smaller profile and I think would lie flat on a winch barrel better than the figure eight loop. As for the perpendicular nature of the loop coming off of an Alpine Butterfly, I honestly don't know if it's an issue or not. That's something to be decided in prototyping, I guess.

Re: Best Stopper Knots for Team Supplied Knots
 

Why? While it was not invented as a stopper knot (more of a starter knot), and uses a lot of line, it's not terribly difficult to tie; I learned it in an hour or so. If you use a single overhand knot as the core, you can nest them, beginning with a "two loop" for the first layer and adding about two loops per layer. For use in the davit fingers with smaller lines, tt also distributes the force of the support quite well.

I agree with this completely. Among the really small knots, the surgeon's knot would be good, presuming the line isn't too slippery for that to hold. If you're willing to use a lot of line, I suggest braiding the lines to each other, which would result in a section which is actually stronger than either line. A bit of web searching turned up the blood knot, which seems to do a great job of relieving the stress in each line before it is doubled over.

Re: Best Stopper Knots for Team Supplied Knots
 

I would go for an alpine hitch or a carrick bend.

Re: Best Stopper Knots for Team Supplied Knots
 

Inventing and understanding knots is right up there in the mix of skillsets that are impossible to automate. These days it's like finding the name of a new planet, star or asteroid - just go ask the expert.

My team doesn't plan to use any knots in the rope for climbing. However, given the ~6mm rope we're testing now we'll need a good DAVIT knot. Are there tricks to making any of the listed knots bigger?

Re: Best Stopper Knots for Team Supplied Knots
 

The 'Ultimate Encylopedia of Knots and Ropework' warns that Figure of Eight and Stevedore knots can both pull through a hole similar in diameter to that of the rope. With the large opening in the Davit, while they may be satisfactory for pulling your robot, may fail with smaller ropes. Figure Eight knots can also travel down a rope.

Suggested instead is the Ashley stopper knot, but if your rope is significantly smaller than the opening in the davit you may need a Monkey Fist to make a large enough ball.

If you're planning to use webbing or Velcro, well, that's a tricky one...

As for joining two similar sized ropes, it's difficult to define a 'best' knot as it depends on the rope material and use case. Many knots may snag or fail under particular or peculiar circumstances. For modern synthetic rope a Simple Simon Double would be worth a look, but I don't know if they'd be recommended for Dyneema or Vectran for example.