Tethered swimmer rescue vector pull review

5417 Views 20 Replies 10 Participants Last post by jmack, Jun 9, 2014

rg5hole

Discussion Starter · Jun 6, 2014

we learn from our mistakes:
Scenario: a swim in a canyon/gorge swimmer on opposite side of river of team. Goal is to get swimmer safely to other side of river.

Here is how we did it and the review that ensued:
Firstly this was a swim in Rockwood box at about 4000cfs, for those of you who don't know that would be the high side of high in a gorge. Pushy big and fast relentless water making swimming and rescue extremely dangerous, obviously the stakes were as high as they get. I had the pleasure of being the tethered swimmer so I will tell from my account.

Firstly I swam, disoriented as I was the first shore that I saw I swam with 100% effort to GET OUT! This happened to be opposite of where I needed to be with a several mile bushwack to fix that problem. There were 5 of us, 1 in a boat, 3 on the opposite shore. We got a throw bag across the river and tethered it to my rescue vest in the rear on the ring (verify your cinch, and check it again). One person anchored and another held the ancor. the object was to pendulum me across the current. Thankfully (here is where we learn) we ADDED A VECTOR PULL. That would be a downstream biner attached to the rope to assist and relieve the pendulum. If you don't know what that is please take a rescue course. When applying a VECTOR PULL assist there will be a tremendous amount of force at an angle which inhibits the vector biner to slide down the rope. Prepare for this by starting your VECTOR PULL as far downstream as possible and obviously get ready to pull like hell.

We succeeded and in review there were a few things to learn from. First, expect the tethered swimmer to be useless. Expect the tethered swimmer to actually submerge so this has to go FAST. If possible move the anchor operation far up the bank as practical to allow the pendulum to work efficiently. ADD A VECTOR PULL, this is critical. For the vector to be effective it needs to be downstream and get ready for a workout it is hard to pull a vector downstream cross current!

Cheers!

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skideeppow

· #2 · Jun 6, 2014

So, even if the tethered swimmer used his arm to ferry, he is still getting submerged?
Also, if you are in a real situation, no one will have a rescue PFD on except the guide, correct? So what would you do?
I have my swift water technician status but still do not understand the biner on the lower rope. Would you use a directional figure 8 then attach the biner? I guess a pix would really help me.

Good stuff, thanks for the info.

rockinRio

· #3 · Jun 6, 2014

skideeppow - sounds like this WAS a real scenario and it sounds like a kayaking party not rafting. Meaning hopefully many would have a rescue vest. At least the guys I kayak with would.

If this happened to a rafting party it would be more complicated. Either the guide separated from the rest of the group making communication difficult. Or swimmer not having the proper gear to be a "live bait" swimmer.

I would like to hear how raft guides would solve this stranded swimmer scenario.

craven_morhead

· #4 · Jun 6, 2014

rg5, thanks for the report. If you had held the main line rather than tethering it to your vest, do you think you could have held on for the entire ride and kept your head out of the water? Would the VECTOR PULL (apparently we have to capitalize this phrase) still have been effective?

glenn

· #5 · Jun 6, 2014

3

Angle of the dangle

Ok quick physics lesson. I am going to over simply some things but the basic message should be sound.

Here is a basic representation of a throw rope (red) and the upstream pull of a rope and the cross current pull of a rope (shown in green). The upper picture shows the rope just as it tags a swimmer. Notice how there is a larger portion of the total pull going towards the shore than upriver. This is good. We want as much of our effort working towards the shore and as little fighting the river.

The second rope shows a few moments after the swimmer is tagged and begins to swing towards shore. Notice how the angle of the pull now means more effort is used to fight the river and less to pull towards shore.

Since the angle of the rope compared to the river is critical one method is to move away from shore. This image shows the same point upstream of the swimmer but one rescuer moves back. Notice the ratio of cross-current pull to upstream pull is better with the rescuer that stands back. The dotted line shows the difference.

Rivers are tough places to move around and stepping back is rarely a simple options particularly in a canyon. Sometimes you have the ability to move downstream. The same effect as stepping back can be gained by pulling on the line downstream of the main anchor/belay. Often a biner on a piece of webbing can be used to slide quickly/easily downstream. This image shows the ratio of cross-current to upstream pull improves with the downstream "vector pull". Again the dotted line shows the difference in efficiency.

These techniques are definitely underused and account for beating up a lot of swimmers who near the shore then catch the full force of the river because so much of the ratio is tilted towards the upstream end.

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glenn

· #6 · Jun 6, 2014

craven_morhead said:
rg5, thanks for the report. If you had held the main line rather than tethering it to your vest, do you think you could have held on for the entire ride and kept your head out of the water? Would the VECTOR PULL (apparently we have to capitalize this phrase) still have been effective?

In my experience clipped in to a rescue vest causes the body to plane and stay on top better than simply holding on. If he went down on the vest it was a hard pull and holding on would have been hard and staying on top wouldn't have happened at all.

glenn

· #7 · Jun 6, 2014

rockinRio said:
I would like to hear how raft guides would solve this stranded swimmer scenario.

A raft may have been able to utilize a zip line to move the raft to the swimmer then pendulum the raft back to shore. There are many factors to consider but this would be one approach. Sending a guide in the zip line raft could ensure correct rigging and may help with a scared/injured/etc guest.

jmack

· #8 · Jun 6, 2014

Jake- regarding just holding the rope, this was not an option because of the situation. The water (all 4000cfs) was NUKING through there and entered the Middle Box only 50 yards downstream. Swim in there at these levels and it is likely game over. However, Russ might have been able to hold the rope over his shoulder and clipped in just in case. This might have gotten him more of an air pocket (more than none). It would not have interfered with the vector pull.

Re- the swimmer using his arm to ferry- no way. The current was far too strong for the swimmer's movements to make any difference.

I (the vector puller) was on the same side as the anchored pullers, so I clipped my rope to the main rope there then went downstream. The vector was clipped to the main rope with a binder so it could slide down. The problem is that once you start to pull, the friction on the rope makes it hard to slide the biner further down the rope.

The vector pull allowed me to speed up the pendulum across the river and pull Russ closer to shore once the pendulum was almost due downstream. As Russ stated, however, it would have been more effective if I went further downstream before I started pulling. Lessons learned.

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rg5hole

Discussion Starter · #9 · Jun 7, 2014

appreciate the dialog here. First, this was a kayaking party and yes, rescue vests are assumed. Second, if I had not tethered I would be dead, there is absolutely no way I could have held on. Third the VECTOR PULL is capitalized becuase without it my party would have engaged in CPR and I perhaps would not be typing. In that regard, Astral Greenvest with the cinch wrapped one time through was how my setup was. The rope was a 1/2" (spectra I think) stolquist, incidentally I enjoy the stolquist bag design it made it easier for me to throw. A DMM revolver biner. Had any of that system failed it would have been fatal, so double check your cinch.

As far as the placement of the biner for the vector pull, the design above shows it on swimmer. This is a valid scenario however, the practical one is to clip the vector in in front of the anchor, then run downstream with it as the swimmer pendulums & hopefully the biner slides toward the swimmer and the vector ends up looking like the diagram (vector biner very near swimmer).

If ever in this scenario just assume the swimmer is unconscious and add a VECTOR PULL.

btw, I say we learn from our mistakes, meaning it was my mistake for swimming. My crew, the rescue scenario & their training, as well as the gear was tight as it gets...obviously as I am still typing. If you are still unclear about such a scenario I recommend looking up Piano, Wigston, Beezley or the other WW-SWR instructors in your area and take the weekend course. It will save a life and it may just be your own.

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Sawatch Rescue

· #10 · Jun 7, 2014

Happy to hear things worked out for you. It sounds like a well coordinated effort when encountering an unforeseen problem with your tethered crossing.

The solution you present is something we cover when teaching contact or 'live bait' rescues in our courses. The scenario you describe is common especially when using a two bag system and you start increasing the amount of line in the water. As you discovered, with line deployed and a longer pendulum it's quite possible for who or whatever is on the end of the rope to become suspended at the end of the pendulum.

Attaching a biner and walking / running down the line is a good option. Of course a micro pulley would be a helpful addition but you will still encounter a good deal of resistance. Another solution you can consider is the use of a Wild Water Snag Plate or the Crossline Reach Rescue System. Both devices give you yet another option when attempting to retrieve the line and draw the tethered swimmer into shore.

Again, happy to hear that it worked out and thanks for posting for everyone else's benefit.

And of course, we always advocate for participation in formal swiftwater courses and getting out there to practice what prove to be perishable skills. Stay safe!

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Mr French

· #11 · Jun 7, 2014

Hey Russ, what about clipping yourself to 2 ropes instead of trying to move the vector pull downstream after entering the water. This way the pull (no longer a vector pull) can be started downstream without the need to move much while pulling. Also without the vector pull, there should be less force exerted on the main rope.

However: You wouldn't be getting the advantage that a vector pull gives you and you would be introducing a second rope (deadly river snake) directly attached to the swimmer.

What was done in your scenario is what I learned from swiftwater rescue class and what I would do if I were in your shoes. Food for thought...

Dave Frank

· #12 · Jun 8, 2014

Russ I am so glad to hear this worked out positively. I have bad to drop of the pendulum as it failed to get me those last dozen feet to shore. Fortunately the next rapid was not the middle box!

To further folks learning, why is a VECTOR better than a second rope that just pulls sideways? Also in my scenario, I probably would have been able to make shore had my upper anchor been fixed, as opposed to a hip belay on a strong, yet lighter than me partner.

I was holding my paddle and using it as a rudder to cross the current. I believe that I a fixed anchor this would be a viable technique

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ouachita

· #13 · Jun 8, 2014

Pulling a vector in the rope gives you a more powerful and faster force without having to pull as hard. It's a mechanical advantage. Pulling a rope in line directly to the swimmer would be like a 1:1. Pulling a vector in the middle would be higher than that.

Think of a webbing anchor. The wider the degree of the angle of the two ends of the webbing you use for your anchor the more tension it puts on the webbing. Which is why you want that angle to be 60 degrees vs 120 degrees.

Sorry I suck at explaining things

Mr French

· #14 · Jun 8, 2014

I believe the vector pull helps bring the swimmer towards the anchor, not straight to shore, so a lot of energy is used to put more stress on the anchor and the swimmer and the rest going towards brining the swimmer to shore.

We used the vector as a means of unpinning a raft; quicker than 3:1 and much less force on the gear (less dangerous). 3:1 systems are being phased out as a means of unpinning crafts since so many injuries occur due to ropes snapping and whipping back at people (redirect or counter weight on the main line helps with this)

And physics wizards out there care to chime in?

glenn

· #15 · Jun 8, 2014

ouachita said:
Pulling a vector in the rope gives you a more powerful and faster force without having to pull as hard. It's a mechanical advantage. Pulling a rope in line directly to the swimmer would be like a 1:1. Pulling a vector in the middle would be higher than that.

Think of a webbing anchor. The wider the degree of the angle of the two ends of the webbing you use for your anchor the more tension it puts on the webbing. Which is why you want that angle to be 60 degrees vs 120 degrees.

Sorry I suck at explaining things

Putting more stress on the end points assumes the end points are fixed. In this case the swimmer is not. With someone moving downstream constantly adjusting the vector angle the swimmer and anchor will actually be under less load than without the vector.

glenn

· #16 · Jun 8, 2014

Mr French said:
I believe the vector pull helps bring the swimmer towards the anchor, not straight to shore, so a lot of energy is used to put more stress on the anchor and the swimmer and the rest going towards brining the swimmer to shore.

We used the vector as a means of unpinning a raft; quicker than 3:1 and much less force on the gear (less dangerous). 3:1 systems are being phased out as a means of unpinning crafts since so many injuries occur due to ropes snapping and whipping back at people (redirect or counter weight on the main line helps with this)

And physics wizards out there care to chime in?

3:1 systems aren't going away. They have a variety of uses that go beyond simply unsticking something. Using the KISS method is a good idea and a vector pull does provide a good way to add a quick shot of power to a system. In my experience several feet of stretch/sag need to be removed from most lines before any real force is applied. Since vector pull advantage is proportional to the angle between the two fixed points creating large deflections during a vector pull before the actual real work needs to happen will likely be counter productive. Again it's simple fast and easy so give it a try.

Mr French

· #17 · Jun 8, 2014

glenn said:
Putting more stress on the end points assumes the end points are fixed. In this case the swimmer is not. With someone moving downstream constantly adjusting the vector angle the swimmer and anchor will actually be under less load than without the vector.

Adding a vector pull will definitely add mor pull on the anchor, fixed or not. The hip belayer is now holding the swimmer and part of the vector puller. The swimmer if being subjected to the force of the downstream flow of water regardless unless the anchor/belayer moves downstream with the swimmer.
Having a second line on the swimmer will alleviate some of the force acting on the belayer if the second line is slightly upstream of the swimmer. If he is downstream if the swimmer he is now pulling on the anchor and the swimmer which would be counter productive.

I'm going to try each method on Thursday at the river and I'll report back if I find a significant difference. Wish I had inline force measuring devices (I'm sure there's a technical term) to get some quantitative data...

3:1 setups are great for many uses but from talking to rescue instructors and professionals and reading online forums they seem to be used less and less for unpinning crafts (east coast seems to be ahead of the curve on this one). The angle of pull is much more important than the amount of force exerted.
Thanks for keeping the discussion going...

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glenn

· #18 · Jun 8, 2014

Mr French said:
Adding a vector pull will definitely add mor pull on the anchor, fixed or not. The hip belayer is now holding the swimmer and part of the vector puller. The swimmer if being subjected to the force of the downstream flow of water regardless unless the anchor/belayer moves downstream with the swimmer.
Having a second line on the swimmer will alleviate some of the force acting on the belayer if the second line is slightly upstream of the swimmer. If he is downstream if the swimmer he is now pulling on the anchor and the swimmer which would be counter productive.

I'm going to try each method on Thursday at the river and I'll report back if I find a significant difference. Wish I had inline force measuring devices (I'm sure there's a technical term) to get some quantitative data...

3:1 setups are great for many uses but from talking to rescue instructors and professionals and reading online forums they seem to be used less and less for unpinning crafts (east coast seems to be ahead of the curve on this one). The angle of pull is much more important than the amount of force exerted.
Thanks for keeping the discussion going...

The force on the swimmer is the same as the force on the anchor. Since the swimmer will be taking less downstream hit on a vector there will be less force on the anchor. Add to this a vector less rescue will last longer which is an important factor in any system relying on people. We get tired quickly.

Edit: If you start the vector with the swimmer at an acute angle to shore already bearing the majority of the rivers force directly on their back the vector will do little to alleviate the forces involved and may increase the force of the hit. I'm talking about getting the vector going immediately after the swimmer leaves shore and traveling the same speed as the swimmer. This is an ideal circumstance but even if you can approach this scenario the hit on the swimmer will be far less severe.

Mr French

· #19 · Jun 8, 2014

Makes sense. Now would keeping the angle between the swimmer and vector greater that the angle between the vector and anchor improve efficiency? Seems like the other way around would pull more on the anchor than on the swimmer.

glenn

· #20 · Jun 9, 2014

In a frictionless system the anchor vector point and swimmer will form a 90 degree angle with the line to the swimmer perpendicular to the current for best efficiency. The swimmer will outrun the vector nearly always so worrying about friction shoreline irregularities and a host of other issues isn't worth it. As the vector runner your job is to not become a victim, hustle downstream and get a hand on the swimmer.

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