Vehicle recovery gear and tips

[Gangly]

I finally got around to finding a calculation for the Force a truck might apply when using a Kinetic Rope.
Kinetic Energy is equal to (Mass divided by Two) times (Velocity Squared). So, (m/2)*(v^2). I'm using pounds, foot-pounds and Feet per Second.

The recommended speed to pull away with a Kinetic Rope is between 2 and 5 MPH, which is 3 to 7.5 feet per second.
My truck weighs about 5,500 lbs when loaded for Recovery work. And we'll use 4 MPH for this example.

Therefore, (5,500lbs/2) * (5.5fps^2) = 83,187 ft-lbs of kinetic energy (force). EIGHTY-THREE THOUSAND POUNDS !!

It's a good thing that the rope absorbs some of this energy, and does not apply the rest rapidly.
Because NONE of the other components (soft shackles, D-rings) can withstand that level of force.

(edited)
AND, typical Kinetic Ropes will Stretch as much as 4 feet. So ... we would divide the force by that much ... cuz it's lbs over some number of feet?
(not just one foot ... ?) Resulting in an overall force of perhaps 20,000 lbs over the distance the rope stretches ... ?

Am I doing this calculation correctly?

footnote: The amount that a kinetic rope might stretch in use was taken from the Project Farm episode where this was tested.

The units of measure once you complete the kinetic energy equation comes to (Lb*ft^2)/(sec^2), which is the Imperial unit of measure for a Joule. A Joule is not a measure of force, but energy, a cumulative measure of force applied over a distance to get from point A to point B. Your intuition is correct though, you can divide the calculated Joules by the amount of stretch in the kinetic rope and calculate the amount of force applied to the rope.

Something you can also do is calculate the spring constant for the kinetic rope by dividing the calculated force by the distance of rope stretch. This will assist in determining the "stiffness" of the kinetic rope. Different manufacturers have different stiffness's for their ropes, which greatly affect the felt tug of a vehicle when doing a pull. The lower the spring constant, the lower the felt tug or acceleration when pulling someone out, which can greatly reduce the stresses on a vehicle when yanking another out. However, if you were to do a practical test, you would only use the first measured values since the kinetic ropes tend to loose their elasticity in repeated tests and do not come back to zero stretch immediately, resulting in the need of a resting period to get "stretchy" again.

Great thoughts vezePilot, it's been a while since I looked at kinetic rope tests.

 

[vezePilot]

An Admin for the Offroad Recovery Portal put out a call at 10:20 PM, forwarding a request from a guy stuck in snow up on Switzerland trail. He was on trails in the South part, very near the mountain community of Sugarloaf Mountain. That's in the Foothills above Boulder.

Hmmm ... man it's kinda late. But I keep lots of gear always loaded, that area is only about 30 minutes from me, and I actually practiced off road stuff there rather recently. At least one other volunteer was responding, and sure enough we found the guy and got there right together. Road to the spot was Brutal.

I was home by 1:00 AM.

I set up for a re-direct from a tree to pull him backwards, and Blaise hooked up to pull him straight sideways.

It didn't actually take very long, winching went well.

Trail Boss on stock 32's went through 12-18 inches of rutted out snow pretty well, including a few big mud/water holes ... Very Impressive!

My stock Trail Boss has excellent throttle response when in 4 LO. If I try too hard in snow, it will start to hop at a rather high frequency and/or start to dig in fast; but backing off and applying very little throttle lets it slowly pull up and out of nearly getting stuck. It seems to be very well balanced in gearing, torque and pedal response. With more experience I can get back in on really terrible roads, and in deep snow. This was a good example: if I wasn't carrying a winch and a full set of chains, I might not have ventured out on the road we had to use tonight.

 

[PistolsFiring]

But I keep lots of gear always loaded, that area is only about 30 minutes from me, and I actually practiced off road stuff there rather recently.

I’ve said it before and I’ll say it again, very appreciative of folks like you willing to spend time, effort to lend a helping hand. As well as share knowledge on forums such as this.

 

[Gangly]

Nice write-up! I'm starting to think that TrailBoss of yours is near indestructible after all the thoughtful mods you've done to it. Kudos to you for getting out in the white stuff and helping those people out, the cold is nothing to mess with.

 

[mrcolieman]

Giving of your time and safety to help another in need is truly a gift... I'm a 27 year veteran of the Fire Service and a retired Battalion Chief. I always am so happy to hear a story like this vs. hearing of a body recovery a week later when someone is missing. Really drives home the importance of being prepared for any and all circumstances when venturing out into the back country. Very well done sir!
CJ

 

[Gangly]

Is it just me, or are the tires on the Tacoma in no condition to be off roading in that environment?

 

[vezePilot]

Ha Ha! He's stuck AGAIN up there! When we got him unstuck he explained that INSTEAD OF following us out, he was going on up a little further to camp the night as he had intended. We told him good night and we'll see you in the morning.

Blaise just sent a Facebook screenshot ... he's still up there. And he's asking for help. BUT ... he hasn't lodged a request for the Offroad Recovery Portal. Maybe because he knows he will just see Curt and Blaise again.

 

[GETGONE]

Looks like he should have spent money on some real tires instead of those "poser" racks and tent deal.

 

[vezePilot]

I try not to judge.
... it's too easy to let others! Blaise said something last night about "college students" and the globally ubiquitous inability to ...
repair weak brain chemistry. Not exactly in those words, IIRC.

And Rory Irish of Trail Mater fame said he has nothing against "overlanding." He just doesn't like the people who do it.

 

[Gangly]

I'm all about overlanding, but your first and second investments should be tires and recovery gear. Start purchasing roof top tents, refrigerators, solar panels, bags, etc. after purchasing tires and recovery gear. Nothing is more irritating than when you go to help recover somebody and they have $5,000 worth of "look at me" goodies strapped to their vehicle, but they have $10 bald tires that cant get grip in wet grass.

 

[vezePilot]

I really like the combined utility of my Trail Boss. Fast and efficient (~20mpg), capable and reliable, powerful off road.
By lunchtime today, Superman had ...

... turned back into clark kent.

.

 

[vezePilot]

Another call this morning, two vehicles buried in snow North of Idaho Springs up in the mountains.
Freeway I-70, Fall River Road, York Gulch, Pisgah Lake rd and then onto the trails ... mostly just keep Left.
I'm loading more gear to go.

Other Trail Boss trucks in Colorado?

 

[Transient]

Another call this morning, two vehicles buried in snow North of Idaho Springs up in the mountains.
Freeway I-70, Fall River Road, York Gulch, Pisgah Lake rd and then onto the trails ... mostly just keep Left.
I'm loading more gear to go.

Other Trail Boss trucks in Colorado?

Are you offering to buy Beau Joe's? Just kidding. I'm in Florida for a couple more years.

 

[ES44AC]

Ha Ha! He's stuck AGAIN up there! When we got him unstuck he explained that INSTEAD OF following us out, he was going on up a little further to camp the night as he had intended. We told him good night and we'll see you in the morning.

Blaise just sent a Facebook screenshot ... he's still up there. And he's asking for help. BUT ... he hasn't lodged a request for the Offroad Recovery Portal. Maybe because he knows he will just see Curt and Blaise again.

You can't fix that .

 

[vezePilot]

On this Recovery (attempted) up North of Idaho Springs, Blais and I had a chance to take a break and talk about our trucks. His 4Runner is tricked out really well, with 5 inch lift, and is running on 35 inch Falken Wildpeak AT3Ws. These were not enough! The two disabled vehicles were really back there, in deep snow. He had his friend Cody just walking out front carrying his Synthetic Winch rope ... cuz they were getting stuck every FIVE FEET.

Another guy, not on the Offroad Recovery Portal list, with a truck on 41's came to the rescue. That guy was still working the incident when Blais and Cody got out. I arrived at the area just as they were out of the worst of it. We parked in a wide turn-around area with great scenic views.

But here's the thing ... Blais has run KO2's and other tires. They are just too stiff in cold weather. Blais used the term "hockey pucks."
The Wildpeaks stay soft and work better in snow.

So it may be that while Steve/PHXPHOTOG has great results with KM3s in the desert of Arizona, the Wildpeaks seem more appropriate for winter up here in Colorado. These are the two tires that I have been considering: BFG KO2/KO3s, or Falken Wildpeak AT3W/AT4W. And the Wildpeaks are less expensive.

And again, we were all very impressed at how well a stock Trail Boss does in deep snow, and rutted out trails. Mine is on the OEM 32" GY Wrangler Territory tires. When you are miles back in on rutted snow, with few places to turn around, it's great to know that this truck can handle it.

This is one sort of situation where the "Trail Boss" earns its name.