
Originally Posted by
the evil twin
At the risk of inciting a riot...
The "damper" mechanics or physics if you prefer are different between a Winch Cable and a Snatchie so I believe what applies to one doesn't necessarily appply to the other.
The damper on a winch cable is to defuse the energy in the cable if a point fails or the longer section of cable if the cable snaps. The ability of the cable to release the energy is a slow process compared to a snatch strap and the entanglement of the damper and intrinsic weight of the cable also get it onto the ground pretty quick.
Snatchies have the slingshot effect and by design are extremely efficient at transferring force to the end of the strap. When a point fails the energy is transferred VERY quickly into what ever object is left on the Snatch Strap. That is why it is MUCH more preferable NOT to use shackles in a snatch recovery. Hook style recovery points or similar are the go if you have them, still bl00dy dangerous tho.
IMHO a Snatch Recovery has heaps more potential danger than winching because the efficiency of damping is significantly less. Lets say a shackle and recovery plate rip out of a vehicle for whatever reason. That lump of metal is going to depart with maximum energy and acceleration and the damper will have no effect until the object has flown past the damper and taken up the slack which is usually about the same time it arrives at the other vehicle so a damper in the middle of the cable doesn't provide a terrible lot of protection.
Another consideration is this. The weight of any damper lying on the ground near the centre of the strap will be flung upwards as the strap takes up. So at the moment of maximum force when the system is liable to fail the weight of the damper is negated as it is still heading skywards.
Sooooo (dare I say it) in light Snatch recoveries I do not necessarily use a damper (I can hear the intake of breath already) BUT in heavy ones I advocate the use of two. One at each end close to the vehicles. 1/4 filled sand bags are perfect