Question about using a come-along with 2:1 rigging

[Tim A]

I was on the trail the other day and a nice jeep guy gave me a come-along for letting him use my air gauge (?!) It looks like it hasn't ever been used.

Anyway, the tool is a Maasdam 122-sb6 rated at 2 tons so it's not capable of rescuing the Tacoma by itself. So, I'd like to explore the possibility of using 2:1 rigging to double the come-along's pulling capacity.

I'm familiar with rigging up a mechanical advantage but this seems different because there is already a 2:1 built into the come-along on the "load" end.

Can someone clear this up? Above all, I want to be able to rescue my rig safely (and with minimal expense). Thanks and sorry for the long post.

 

[Eric S.]

It will probably work by itself for many cases.
Rigging with snatch block would be no different than a come-along without a built in 2-1:

-snatch block securely attached to anchor point (with tree strap or chain)
-one end of winch-line extension (like Amsteel Blue or cable) connected to proper tow point on truck
- pass winch-line extension through snatch block and connect the to come-along
- other end of come-along attached to tow point of truck
-through a blanket or something over the winch-line extension and start cranking

The pain about come-alongs is most are quite short. A length of chain between the truck and the come-along makes it easier to re-rig.
Oh and if the truck might roll over you once it is dislodged you might want to rig it to the snatch block is attached to the truck
Hope that made some sense.

You might want to check how long of a cable is on the come-along just to see how often you will have to re-rig. Remember if you use a snatch block with it your truck is only going to move 1/2 that distance.
Do you have a Hi-lift?

 

[Tim A]

It will probably work by itself for many cases.
Rigging with snatch block would be no different than a come-along without a built in 2-1:

-snatch block securely attached to anchor point (with tree strap or chain)
-one end of winch-line extension (like Amsteel Blue or cable) connected to proper tow point on truck
- pass winch-line extension through snatch block and connect the to come-along
- other end of come-along attached to tow point of truck
-through a blanket or something over the winch-line extension and start cranking

The pain about come-alongs is most are quite short. A length of chain between the truck and the come-along makes it easier to re-rig.
Oh and if the truck might roll over you once it is dislodged you might want to rig it to the snatch block is attached to the truck
Hope that made some sense.

I had to read a couple of times but I think I get the picture. Thanks ERratIC.

What I'm used to (fall protection training) is that however many lines are leaving the load (i.e if using one snatch block, that's 2:1) and it doesn't matter if the snatch block is at the load or anchor. But if the snatch block is at the load, why would that help if the vehicle (load) rolls? Sorry if that's a dumb question, but I'm new to this.

 

[Haf-E]

The problem with these small come-alongs is that the amount of cable which can be spooled out is so limited that by the time you use most of it to tighten up the rigging (pulling out any slack and stretching straps, etc) you will only move the vehicle a few feet forward - then you will need to re-rig and do it all over again - usually with the vehicle slipping back a foot or so when you let the come along go loose to re-rig the cable.

When you combine this with a pulley to do a 2:1 pull - the amount the vehicle moves forward on each pull is 1/2 as much...

So - its a frustrating process. A real "walking" type hand winch (like a Tirfor or similar) works so much better. There also are larger come-alongs which have much bigger spools on them also.

 

[Eric S.]

But if the snatch block is at the load, why would that help if the vehicle (load) rolls? Sorry if that's a dumb question, but I'm new to this.

If the snatch block is at the truck end, that just means you and the come-along are farther away from the tuck

 

[Tim A]

The problem with these small come-alongs is that the amount of cable which can be spooled out is so limited that by the time you use most of it to tighten up the rigging (pulling out any slack and stretching straps, etc) you will only move the vehicle a few feet forward - then you will need to re-rig and do it all over again - usually with the vehicle slipping back a foot or so when you let the come along go loose to re-rig the cable.

When you combine this with a pulley to do a 2:1 pull - the amount the vehicle moves forward on each pull is 1/2 as much...

So - its a frustrating process. A real "walking" type hand winch (like a Tirfor or similar) works so much better. There also are larger come-alongs which have much bigger spools on them also.

Good point Haf-E. This come-along is only a couple feet longer than my Hilift so it might not even be worth carrying.

 

[Tim A]

If the snatch block is at the truck end, that just means you and the come-along are farther away from the tuck

OK I gotcha. Thanks:beer:

 

[opie]

The 2:1 rigging with a come a long is going to be a long tiring process.

But as a user of a come a long also, I've been toying with the idea of using an adjustable sling on one end to speed up re-rigs using a come a long. I'll need to crunch some numbers to find a suitable size rope to get it done. They can be made from either Amsteel Blue or a 12 strand polyester.

 

[Eric S.]

To speed things up you could replace one of the hooks on the come-along with a 3/8" chain grab hook. Pack some 3/8 chain along and you can just keep working your way up the chain. Kind of heavy but 20' or so of Chain might come in handy anyway.
A hook like this.

In a pinch I have removed the bolt that holds the end of the cable to the come-along to get some extra length. It would only be a 1000lb come-along but it still might be enough to move the truck. I had to do it because needed to use a rope to reach an anchor. Problem was the rope had too much stretch in it. Like Half-E mentioned all the slack was taken up and the truck didn't move yet. It was a pain but it did work. The next weekend I purchased a Warn and vowed never to use anything with stretch in it with a come-along again.

 

[Tim A]

The 2:1 rigging with a come a long is going to be a long tiring process.

But as a user of a come a long also, I've been toying with the idea of using an adjustable sling on one end to speed up re-rigs using a come a long. I'll need to crunch some numbers to find a suitable size rope to get it done. They can be made from either Amsteel Blue or a 12 strand polyester.

Thanks for chiming in opie. I knew ExPo had a guy who spliced rope but I could not remember your username.

Your post got me thinking about prusiks. On our rescue 4:1s at work, tension is held by a prusik while the rigging is reset. Now, I realize that I am dealing with ALOT more weight when trying to recover a vehicle.

Perhaps a large polyester rope (like 13mm, 42kN) could replace the winchline extension and a slightly smaller prusik cord (say 11/12mm) be used to secure the load while the come-along/Hilift is reset? What I'm not sure about is poly rope's durability and value vs. synthetic winchline.

 

[opie]

Thanks for chiming in opie. I knew ExPo had a guy who spliced rope but I could not remember your username.

Your post got me thinking about prusiks. On our rescue 4:1s at work, tension is held by a prusik while the rigging is reset. Now, I realize that I am dealing with ALOT more weight when trying to recover a vehicle.

Perhaps a large polyester rope (like 13mm, 42kN) could replace the winchline extension and a slightly smaller prusik cord (say 11/12mm) be used to secure the load while the come-along/Hilift is reset? What I'm not sure about is poly rope's durability and value vs. synthetic winchline.

I was actually thinking of a whoopie sling. Made out of suitable rated Amsteel Blue or Tenex. Tenex is a 12 strand hollow braid like Amsteel Blue, but polyester instead of SK75.

I wonder what diameter rope one would need in order to use a prusik system. I know Amsteel Blue is a little to slippery for a normal prusik. A Klemheist may be a better suited prusik for this situation. But I still dont know if it would hold fast up to the tensile point of the line. I also think that any double braid rope used in sizes that would accomodate the loads here may leave something to be desired. Cimbing and resuce ropes outer braid is wound a little tighter than the double braid ropes we offroad folk use.

Ive got some 3/4 tenex in the shop. But that would probably be a little bulky. 3/8 or 7/16 Amsteel Blue would fit the bill a little better while carrying near the same load.

 

[Tim A]

I was actually thinking of a whoopie sling. Made out of suitable rated Amsteel Blue or Tenex. Tenex is a 12 strand hollow braid like Amsteel Blue, but polyester instead of SK75.

I wonder what diameter rope one would need in order to use a prusik system. I know Amsteel Blue is a little to slippery for a normal prusik. A Klemheist may be a better suited prusik for this situation. But I still dont know if it would hold fast up to the tensile point of the line. I also think that any double braid rope used in sizes that would accomodate the loads here may leave something to be desired. Cimbing and resuce ropes outer braid is wound a little tighter than the double braid ropes we offroad folk use.

Ive got some 3/4 tenex in the shop. But that would probably be a little bulky. 3/8 or 7/16 Amsteel Blue would fit the bill a little better while carrying near the same load.

I'm not familiar with the practical use of a whoopie sling.

I know that the more loops you put in a prusik, the better in that the crushing weight is spread over a larger area. Not sure I want to be the first to try a vehicle recovery with a prusik system though. I need to look around the web some more.

We have tons of 5/8" kernmantle at the shop that is about to be thrown out so I'd love to take advantage of that.

 

[Quill]

Use it at home with a pair of gloves before you really need it. I have two of them. Poor man's winch and engine hoist. The good ones can rip and pinch shin. The bad ones fail and cause serious injury. They need getting use too. I cussed mine and threw them down the road road more than once. That said a good one in experienced hands can be helpful. Winch your rig up on a trailer a couple of times to learn the dynamics of one.

 

[opie]

I'm not familiar with the practical use of a whoopie sling.

I know that the more loops you put in a prusik, the better in that the crushing weight is spread over a larger area. Not sure I want to be the first to try a vehicle recovery with a prusik system though. I need to look around the web some more.

We have tons of 5/8" kernmantle at the shop that is about to be thrown out so I'd love to take advantage of that.

The issue I see with kernmantle is all the strength is in the core (kern) and the prusik would essentially be pulling on the sheath (mantle). Not so much an issue for body weight or arresting a fall, but it might be to much for a vehicle recovery. Not to mention most, at least what Ive seen so far, kerns are nylon.

Whoopie slings are used by arborists to attach their rigging to the base of a tree. Also used by line workers for the same purpose but on power poles. Usually made from Tenex or some other spliceable polyester but occasionally youll find them made from Amsteel Blue. You have a fixed eye on one end and the other end is an adjustable eye. They can be made in just about any length minus the minimum you need for the eye and the adjustable bury. Samson states that the sling derates the average strength of the line by up to 40%. But some correspondence I had with one of their splicers (which Im trying to find) said the real world number is closer to 20% with the failure point being the exit for the tail of the adjustable bury.

I think one with an adjustment range between 5-20' would work well. One made from 3/8 would have a strength rating of just over 15,000, well above what you can accomplish with a come-a-long. The issue is it would take about 45' of line, and puts you in the ballpark of a 50' extension as far as price goes. Might not be worth mitigating the headache of re-rigging.

 

[Tim A]

Use it at home with a pair of gloves before you really need it. I have two of them. Poor man's winch and engine hoist. The good ones can rip and pinch shin. The bad ones fail and cause serious injury. They need getting use too. I cussed mine and threw them down the road road more than once. That said a good one in experienced hands can be helpful. Winch your rig up on a trailer a couple of times to learn the dynamics of one.

I hear you. Practice makes perfect.

The issue I see with kernmantle is all the strength is in the core (kern) and the prusik would essentially be pulling on the sheath (mantle). Not so much an issue for body weight or arresting a fall, but it might be to much for a vehicle recovery. Not to mention most, at least what Ive seen so far, kerns are nylon.

Whoopie slings are used by arborists to attach their rigging to the base of a tree. Also used by line workers for the same purpose but on power poles. Usually made from Tenex or some other spliceable polyester but occasionally youll find them made from Amsteel Blue. You have a fixed eye on one end and the other end is an adjustable eye. They can be made in just about any length minus the minimum you need for the eye and the adjustable bury. Samson states that the sling derates the average strength of the line by up to 40%. But some correspondence I had with one of their splicers (which Im trying to find) said the real world number is closer to 20% with the failure point being the exit for the tail of the adjustable bury.

I think one with an adjustment range between 5-20' would work well. One made from 3/8 would have a strength rating of just over 15,000, well above what you can accomplish with a come-a-long. The issue is it would take about 45' of line, and puts you in the ballpark of a 50' extension as far as price goes. Might not be worth mitigating the headache of re-rigging.

Ah I see what you mean about the kernmantle. You know your stuff man and I will no doubt be coming to you if the need for rope arises.

So, a whoopie sling acts as an anchor point by running one end thru the loop and creating a choker?