Basic Recovery Techniques
If you don't have a winch installed, and quite often even if you do, a rope or strap recovery may be required to free either your vehicle or some one else's. There are two basic ways to preform a recovery with a rope or strap; first is to simply pull the stuck vehicle free, the second is to perform a "snatch" recovery, sometimes referred to as KER (Kinetic Energy Recovery), for reasons that will become obvious. The first method may work when you are recovering a vehicle that is very lightly stuck, but on the trail you are more often than not going to encounter vehicles that are seriously stuck, and a snatch recovery method will be called for.
Equipment
To perform a snatch recovery, first and foremost you will need the correct equipment. For performing snatch recoveries with a vehicle the weight of the H2, a minimum of either a 3" or 1" rope is required and at least 3/4" shackles. A bridle is also desirable, this is a short strap or rope, usually 8' or 10', that will go between both the H2 towing hooks allowing for a more even distribution of forces on the H2, a suitable tree strap can also double as a bridle. It is important that you know your equipment and know it's safe working limits, and ensure that it is in good working condition.
Some people prefer to use straps, usually 3", preferably with some sort of protection around the loops. Straps will stretch and this will allow for a more gradual transfer of energy. I personally carry 3" and 4" straps and a 1" synthetic rope specifically designed for snatch recovery. Never use chains for snatch recovery, nor the cheap 2" straps with built in hooks, both can be potentially dangerous.
The Theory
Before we look at how to perform a snatch recovery let us quickly look at the principle involved. Kinetic energy is energy that is transferred due to motion. What we are effectively doing is transferring the energy of the moving vehicle performing the snatch to the stuck vehicle. It is a very simple law of physics, but one that allows us to allow free stuck vehicles. To perform a snatch recovery a certain forward momentum must be achieved, otherwise the energy to be transferred will simply be absorbed by the tow rope or strap, and no progress will be made. The elasticity of the rope or strap will actually assist in the transfer of energy, it will also dampen the transfer of energy reducing the likelihood of any vehicle damage. But when you should be aware that when you are transferring several tons of energy there is the possibility for damage. By using the correct equipment and following some simple guidelines this damage potential can be reduced.
First Things First
Before you do anything, stop, assess the scene, discuss possible extraction methods with other experienced drivers, then decide on the best course of action. Do not rush, take your time and explain to those involved what is going to happen and gain their permission for any extraction you are going to attempt.. Gather the necessary equipment and inspect it to make sure everything is in good condition, if you do not have everything needed yourself, ask others. Look underneath the stuck vehicle, is there anything that may be damaged when you pull the vehicle? Check front and rear, which will be the best direction to make the extraction? Once you have assessed everything and thought it through, it is time to recover the vehicle.
The Snatch
Position your vehicle where it will be safe and able to be connected to the stuck vehicle, check the route that you will be pulling, and ensure that everyone not involved in the recovery is out of harms way. Connect the rope or strap to the stuck vehicle, use a bridle if have one available and always use shackles. Do the same to your vehicle, ideally to the rear of the vehicle. If possible use a spotter safely away from the vehicles in a position that he can communicate to both drivers, rehearse hand signals before you start the recovery. Both drivers should have their seat belts on and no else should be in the vehicles. Gently drive forward until the rope or strap is taught, then try and pull the stuck vehicle forward, the driver in the stuck vehicle should try and drive forward at the same time, but do not spin your wheels as you may make matters worse. It is often worth checking to see if a light pull will free a vehicle. If not it is time to snatch the vehicle.
With the aid of a spotter back up 10' to 15' towards the stuck vehicle, the spotter should ensure that you do not drive over the rope or strap. With the spotter back in a position of safety he should give an all clear signal, then a signal to "Go", the driver of the recovery vehicle should now accelerate forward at a reasonable rate, experience will teach this, and the driver in the stuck vehicle should be ready to drive forward. When the strap or rope reaches it's limit, the forward momentum (kinetic energy) will be transferred to the stuck vehicle and yank it forward. Several attempts may be needed, but it will generally work on even the hardest stuck vehicles. Be aware of driving over the strap or rope and of hitting vehicles, obstacles, trees, etc.
Due to the stresses, sudden jolts, lack or gain of traction, that may be transferred to the drivelines of the vehicles, it is preferable not to have anything "locked" unless absolutely necessary.
Basic Rules
As with everything, there are some basic do's and don't's with a snatch recovery;
- Use a rope or strap man enough for the job
- Do NOT use straps with built in hooks, use a strap or rope with shackles
- Do NOT attach to ball hitches or anything else that can easily break off
- Make sure every one is clear of the area
- Use a bridle if possible to evenly distribute the force
- Wear your seat belt, you will need it!
- Have a spotter at a safe distance
- Make sure all parties are aware of what is happening
- Take your time, assess the situation, think before you act
Summary
Snatch recovery is a perfectly safe (provided you are using the right equipment and know what you are doing) and accepted practice when on the trail. There are other recovery techniques, such as jacking, winching, etc that are also useful, but the snatch recovery is probably the most commonly used. This basic info is not meant to be an authoritive guide to snatch recovery, and if in any doubt you should consult with someone experienced in this type of recovery. Finally, it is also worth remembering the old adage, "Better a stuck vehicle, than an injured person". If at any time there is a possibility of someone getting injured or damage to a vehicle, stop the recovery and call in the experts. Notes
Obviously, when dealing with other people's vehicles you want to make sure you have their permission for any type of recovery you may perform and that they fully understand what you are going to do. If they are not 100% comfortable with you performing a snatch recovery, do not do it. Ideally, if they are able, have them make the connections to their own vehicle, and you just check them for safety. While it is unlikely that any damage will occur as the result of properly executed snatch recovery with the correct equipment, things can and do break from time to time. Make sure the person you are recovering is aware of this and accepts that risk, preferably witnessed by others.
11-14-2007, 04:46 AM
Basic Recovery Techniques
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