Getting out of a pickle (recovery gear)

We have chosen a 4×4 because we enjoy going off the beaten track to remote areas (see our Africa Blog and South America Blog). There is therefore always the possibility of getting stuck!  Obviously we will take a good shovel or two for the old-fashioned digging solution. But we have also considered some 21st Century 4×4 recovery gear to get us out of a pickle.

Over 5 years living in the Middle East, our extensive experience of driving (and in the early days, occasionally getting stuck!) in sand and deserts has taught us a lot about: (i) avoiding situations where we are likely to get stuck; and (ii) what 4×4 recovery gear to carry to get ourselves out if we do get stuck.

Tyre Pressures

We learned in our early days of desert driving that a quick and easy method of accurately deflating and re-inflating tyres is essential.  Vehicles which are otherwise extremely capable off-road can often get stuck in soft sand simply because they have tyre pressures set too high.  With hot and soft sand, tyre pressures should be no more than around 10 to 15 psi. Any higher and the vehicle is likely to sink. Speed (or maintaining momentum) is also important, but importantly, turns must be gradual so that low pressure tyres aren’t popped off the bead.

Sand Ladders (traction boards)

These are invaluable for situations where tyres can’t get traction (e.g. in sand or mud).  We are aiming to take four sand ladders. This may seem excessive, but having spent time digging 4x4s out of sand when it’s over 50°C, we think these are worth the weight/payload on the back of the Truck.  If a tow-out is not available, it is often much easier to jack the vehicle up, rest it on 4 sand ladders and drive away at speed, than it is to dig out!

Kinetic Energy Recovery Rope (KERR)

Another item of equipment which I have found from experience to be essential is a KERR. Forget snatch straps; they only stretch by about 10% max, and should then be left for 24 hours to recover after each use.  A good KERR will stretch by about 30% and can be used over and over again.  We have been using KERRs in the desert for the last 5 years; they are truly amazing and have to be seen to be believed.

The basic problem with towing a vehicle in sand, is that the towing vehicle often ends up digging itself into the sand too.  The principle of the KERR is that, rather than the towing vehicle using purely its own power to tow the stuck vehicle, it accelerates away with plenty of slack in the KERR and the kinetic energy in the moving vehicle is passed smoothly through the stretchy KERR as it is pulled taught.  This energy pops the stuck vehicle out of its hole and the towing vehicle doesn’t dig in at all.

Using this technique I have managed to pull out vehicles which are much heavier than the towing vehicle, up hill and in soft sand.  A Toyota Fortuner towed a Hummer H2 out of sand, stuck on its chassis, with all 4 wheels spinning; the Fortuner didn’t dig itself in at all!).

One significant caution however, is the tremendous force that can be generated with the KERR. You must keep people clear and use top-quality recovery points, ideally using a bridle between two points to spread the load.

We have just bought a new KERR for the truck from Marlow. It is rated for vehicles between 3 and 5.5 tonnes!!  Their highest rated KERR is for battle tanks at 55 to 65 tonnes, so they can supply for your vehicle no matter how much it weighs! See link at  http://www.marlowropes.com/index.php?option=com_content&view=article&id=154&Itemid=164

Other tow ropes

In addition to the KERR, we will also carry:

  • three nylon 24mm tow ropes (rated at 12 tonnes);
  • one 2m long for use as a bridle;
  • one 4.5m long for road towing or use as a bridle; and
  • one 15m long one for reaching vehicles when I don’t want to get the towing vehicle too close due to the terrain.

See  http://www.firstfour.co.uk/products/towing–jacking—recovery/tow-ropes

Winch

There is a lot of debate about winches and their usefulness. Having researched this a lot and considered our Truck and our previous experience, we have decided to fit one as part of our 4×4 recovery gear.  On the downside, they are heavy. But with the weight hanging so far forward, this is actually helps our load distribution by moving more weight onto our front axle.

The research into the required winch capacity indicated that we need about 50% more capacity than the vehicle weighs.  This is so that:

  • the winch is not struggling when you are stuck up to the chassis in sticky mud on a slope
  • you don’t need to unwrap back to the first roll of cable on the drum
  • it’s not necessary to use the pully-block for every recovery; and
  • the winch is not overloaded or strained, so it should last longer.

Hydraulic or electric?  I finally decided on electric over hydraulic. This is because the winch will (hopefully!) go for long periods without use.  With low use, the seals on a hydraulic winch are likely to perish, so I am hoping that an electric winch will need lower maintenance in this respect.

Which one?  I finally settled on the Warn 16.5Ti.  Of the companies that I found in the research, Warn seems to have the widest global presence; this should help us find a dealer for spares if necessary. The 16.5Ti is a 12V model and the 16,500 lb (7,484 kg) pull capacity is close enough to our target requirement.  I have replaced the standard steel cable with 30m of 11mm Marlow Dynaline Max winch line.  The advantages of switching to a synthetic cable are:

  • it has a breaking strain of 14,051 kg
  • the full 30m of cable actually weighs less than the 3.15 T hook fitted to the end of it!!
  • it floats (handy for towing out of water!)
  • it has no stretch, so if it snaps it simply drops to the ground without the dangerous ‘whip effect’ that comes with steel cables.

See  http://www.marlowropes.com/winch-line-menu/dynaline-max.html

To go with the winch, I have chosen a 16.3 T Superwinch pulley block for offset winching or doubling the pull or halving the speed, should it be needed.

Shackles, straps, chains and other 4×4 recovery gear

We are taking a selection of shackles, straps and a chain as part of our 4×4 recovery gear.  Initially I could not make sense of the load ratings on the various options available. Having done some research, it seems that as a general rule the following safety factors are applied as they are designed for lifting applications: chains 3:1,  shackles and hooks 6:1,  and straps 7:1 (but it is important to check all of these with the manufacturers).

To calculate the breaking strain, you take the rating on the component and multiply it by the safety factor.  So for my hook, rated at 3.15 T with a safety factor of 6:1, its breaking strain for lifting is 18.9 T.

However for towing and horizontal winching, a safety factor of 2:1 is used.  So for my 3.15 T hook, using a safety factor of 2:1, it can be used to tow or winch horizontally loads of up to 9.45 T.

I have used the above to plan my equipment (although the original winch cable supplied with the Warn winch had a safety factor of only 1.24:1).

I have only chosen properly rated equipment for my 4×4 recovery gear. Given the forces at work during towing and recoveries, I don’t want to risk death or injury in a remote area by using a cheap under-rated component!  I have found that industrial rigger shops supplying construction contractors,  often have the rated parts at better prices than many 4×4 shops.

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