Basic Recovery Kit

Don’t ever venture out without some basic equipment to assist you in extricating stuck vehicles.  It’s often a long walk home and your mates don’t really want to leave their warm house at some ungodly hour to come and rescue you because you went out ill prepared in the first place.

In order to use your recovery equipment to it’s maximum potential, you will need some or all of the accessories that are mentioned in this section of this guide.  When purchasing equipment always attempt to buy equipment that has been rated.  It will often cost a little more, but your life and the lives of others may depend on these items some day and rated equipment is a known quantity, unlike its non-rated equivalents.  This is important, as you do not want your accessories to become ‘the weak link in the chain’.

If you do decide to use non-rated, untested equipment you will have no idea as to its design parameters or the point at which it will fail.  You can probably realise now why, when choosing accessories it is vital to bear in mind the need to purchase quality made, tested equipment and accessories.

rating labelDon’t be conned by sales people telling you it’s tested and rated equipment.  If your equipment has been rated it will have been labeled (see photograph opposite) or stamped to prove this.  If it has been tested you will also get a test certificate from the manufacturer or vendor.   The strop in the photograph has been rated at different rates dependent on the configuration in use.  Always check the configuration loading before you actually use it.  No label, stamp or certificate = no purchase.

 

Good quality rigger type Gloves
Always wear a good quality pair of leather or hide rigger type gloves.  You only have, as they say, only one pair of hands.  Look after them and wear gloves whilst handling equipment.

Pioneer shovel and pickaxe.
These are cheaply and readily available from ex military suppliers nationwide.  A real asset that is versatile to the point of being a must have item.   Apart from the obvious uses of digging, the shovels also make a good standby high lift jack base to prevent it sinking into the ground during use.  They can also be used to dig latrines (if one is caught short in the boonies) re-direct ruts by digging “points” much like a railway line and the pickaxe is very useful for retrieving other equipment that has sunk into the ground.


Recovery rope(s) and strops
Now you will note the term ‘recovery’ was used here not the term ‘tow’.  There is a big difference.  Towropes are designed to sustain the weight of a vehicle during road recovery work and were never designed for the extreme loadings that are placed on ropes during off road recoveries.

I recommend the use of 24 to 26 mm nylon ropes for off road recovery work.  They have a minimum breaking strain of 10, 12 and 13.9 tonnes respectively and are stronger, as Nylon is the strongest man made fibre available.  Polyester and polypropylene are not as durable but do have qualities that are useful.  Polyester for example will resist attacks by acids and is unaffected by oil, organic solvents and bleaching agents.  Polypropylene is a lightweight man made fibre that his highly resistant to attacks by oils, acids and alkalis.  However it is affected by bleaching agents, solvents and is most prone to rot.

 

The table below shows the relative minimum breaking strains IN METRIC TONNES of three different types of recovery ropes that are readily commercially available.

DIAMETER NYLON   POLYESTER POLYPROPYLENE
22MM 10.00 7.62 6.5
24MM 12.00 9.14 7.6
26MM 13.90  10.70 8.8
       

Ultimately the choice is an individual one as all these ropes will cope with a two tonne Land Rover that needs recovering.  However the Nylon ropes do offer the biggest safety margin of all three types.  Look for example at the difference 2mm can make between Polypropylene and Nylon.  Which would you rather be using, the 22mm polypropylene at 6.5 t of the 24mm Nylon at 13.90t.  No contest!! Is there?

You should aim to carry a short rope of about 4.5m in length (this is the max legal length for towing on the public highway) and a ten-metre rope for those situations when you can’t get in as close as you might like to.  Ropes should be kept clean, coiled up and of direct sunlight, as Ultra Violet rays will degrade any type of fibre rope over time.

Recovery strops (as long as they are rated for the purpose) are just as effective as ropes and usually easier to clean afterwards.  A rated strop will have a label attached to it stating it’s safe working load (SWL) in different configurations.  E.G. in a single pull it may be rated for ten tonnes but doubled up will pull twenty etc.   If your strop does not have a label attached to it (unless you cut it off) it will not have been rated or tested to ascertain its SWL.  In that case it is a lottery as to what the strop will safely handle.  The morale here is always buy rated recovery equipment.  Your safety and that of others may one day depend on it.

The Kinetic Energy Recovery Rope (KERR)
Not to be confused with a standard recovery rope, the kinetic energy recovery rope is a different piece of equipment altogether and should only be used by personnel who understand the working principles of these ropes.

Kinetic Energy Recovery Rope’s work by storing kinetic energy supplied by the recovery vehicle and transferring it to the vehicle being recovered.  The recovery vehicle sets off at between 10 and 15 mph (dependant on the bogged vehicle weight) and when it can pull no farther applies the brakes.  The stored energy in the KERR will usually then be transferred to the stranded vehicle, extricating it from its stuck position.  A word of warning here though, you will not move a stuck two tonne Land Rover using a 900kilo Suzuki as the recovery motor.  The Suzuki will end up springing backwards into the Land Rover, which will then have a new, distinctive look to its front end.  In some circumstances where grip is very poor the recovery vehicle can also slide back to its original start point, achieving precisely nothing.

The table below shows them towing vehicles required speed to extricate the stuck vehicle of a pre-determined weight using a 24mm diameter 8metre long KERR.  24 mm ropes are rated for vehicles with a maximum allowable mass (or gross vehicle weight {GVW}) of up to 3.5 metric tonnes.

           

Bogged vehicles gross weight Towing speed for vehicles weighing
Vehicles weighing up to 1.5 tonnes  15 mph
1.5t up to 2 tonnes  13 mph  
2t up to 2.5 tonnes 12 mph
2.5t up to 3 tonnes 11 mph
3 t up to 3.5 tonnes   10 mph

 Under no circumstances should you ever use a damaged KERR.  The amount of energy it stores can, if abused and misused cause potentially lethal circumstances and will inevitably cause serious damage to the vehicles involved. Always inspect the rope before each time you intend to use it.  When you have finished with it, wash it using fresh water and avoid using any detergents.  These ropes do not like detergents, solvents or acids and should not be kept in direct sunlight as Ultra Violet light will weaken and eventually destroy the fibres in the rope.


You must however take into account the weight of the stricken vehicle and add the surface co-efficient factor and any gradient factor to assess the required pull.  When this is known, the towing vehicles speed can then be determined using the table above.

Having said all that, in certain circumstances the KERR is a good bit of equipment to have in your tool kit.  Used properly it can be very effective at removing a well-stuck vehicle from its situation.  Later on we will discuss the forces that need to be applied under different recovery situations.  Once you understand these theories, the use of the KERR will become more apparent to you.  It will be a lot more obvious when and how you should use it and when you should definitely not do so.

D and Bow Shackles
shackleAn assortment of both D and Bow type shackles is essential to connect the various accessories to your vehicle.  Shackles should ideally be rated at a minimum of 3 tonnes lifting.  This means they will be good for 9 tonnes (hauling).  Any equipment that has been rated for lifting purposes will automatically be rated at three times that amount for hauling purposes.  You should never use any shackles that have not been rated and tested for the job you are going to use them for.  D shackles are useful for connecting single items such as ropes.  Bow shackles come into their own when connecting a bridle for example, where the direction of pull is not necessarily always the same.  A bow shackle will however work, as a D shackle will in single connections.  If you have to choose when purchasing shackles, always buy Bow shackles for that very reason.

 

 

Vehicle Anchor Points                  

recovery pointOnly use vehicle anchor points that have been designed specifically for that purpose and fitted correctly, using high tensile steel bolts.  There is a great deal of personal choice here, just ensure that your anchor points are rated for the job and very well fitted.  You can see in the photograph opposite how the anchor points on this vehicle are connected directly to each chassis leg via a 10mm plate.  This was purposely designed to sustain the extreme forces applied to it during severe recovery exercises.

The use of tie down points on vehicles is not recommended for recovery purposes, as they are not designed to sustain the amount of load you will invariably apply to
them.  There is every chance you will simply pull them straight off!!

 

 

 

Bridles

Bridles are short Nylon ropes with a loop in each end that are used for connecting two legs of a vehicle chassis together in order to spread the load imposed upon it.  I would always recommend their use in anything other than a light recovery situation.  Imagine being hauled from a bog by only one arm.  It would severely stress your shoulder on the side from which you were being pulled and cause you great pain.  If you were pulled out using both arms, the load would be evenly spread and the pain substantially reduced.  Now apply that analogy to the vehicle chassis.  The load is more evenly spread along the chassis, resulting in less mechanical stress and less chance of twisting, damaging or pulling things of the vehicle.

Hi-Lift Jack
As the name suggests Hi-lift jacks provide a higher than normal lifting capacity to raise the load, in this case our vehicle, above the ground.  They are useful for casting vehicles out of ruts, raising vehicles in order to build up the ground beneath them and for changing wheels in very rough terrain.  Always use a base with a hi-lift jack in order to prevent it sinking into the ground.  If you do not have a base for this purpose, your shovel will act as a base for your jack in an emergency.  Hi-lift jacks can also be used as winches, (providing you have a suitable chain to use with it), clamps and spreader bars, for parting trees for example.

Various adapters are now available to suit these jacks.  Two in particular spring to mind.  Firstly, the wheel lift adaptor for lifting vehicles that have no means of being lifted using the bodywork, chassis or bumpers.  Secondly, the sill lifting adaptor. This adaptor allows the jack to be used with vehicles that have strengthened sill bars and/or front bumpers with these points fitted.

Hi-lift jacks should always be used with care.  The handle should always be stored in the upright position during all periods of use, except when being cranked up or down.  Exercise caution when jacking up or down as the handle can, in certain circumstances, self perpetuate and slip from your hands as it goes into auto pilot and runs all by itself.  Do not get near it under if this occurs, as there is a serious risk to personnel safety to the face and upper body from the flying handle.

Sand Waffles
Sand waffles are very useful pieces of equipment for several reasons.  Firstly they are capable of bridging short gaps such as ruts and ditches.  Secondly they will spread the vehicles weight on very soft ground.  Thirdly they will act as traction mats, and as a substitute hi-lift jack bases.  But last and not least sand waffles are really useful tools for climbing steps, such as when you exit a stream or river or need to climb out of any hole you find yourself stuck in.  I would recommend that you carry four of the lightweight plastic variety.  In extreme cases you will need one for each wheel and for very heavy vehicles they can be doubled up to help spread the weight of the vehicle(s) between them.

In this section I have tried to put together what I would consider to be a good basic off road recovery kit list.  Whilst all the items listed are not compulsory they are all useful in conjunction with each other.  If you can afford to purchase everything in the list and know how to use the equipment to its best effect, you will almost certainly be able to recover yourselves and others in 95% of situations you will come across.

 

The mechanics of how it all works

To obtain the best results and the optimum efficiency from your recovery equipment you should understand the principles of the mechanics of recovery operations.  For recovery purposes the resistance to motion is dependant on four main factors.

These are the four main factors to consider.

  1. The resistance to any movement of the load you intend to pull.
  2. The total weight of the vehicle.  (A 2000 kg vehicle in these examples).
  3. The nature of the ground surface that has to be negotiated.
  4. The gradient (if any) to be negotiated.

The resistance to movement depends on any factor that will cause drag.  The terrain and any damage such as flat tyres or a bumper that is pressed onto a wheel will add to the total effort required to move the load. It is usually best to change any flat tyres and straighten any bent bumpers before recovery commences to reduce drag to a minimum.  For the purposes of this section we will assume that the load in question is a two tonne (4400 lbs) Land Rover on inflated tyres and having sustained no damage. However don’t forget to add the weight of any load that you may carry in the calculation.

The surface through which you will recover the load also has a bearing on the amount of effort required.  Rolling resistance on tarmac is substantially less than in deep mud for example.  A vehicle on level tarmac will require an effort equal to 1/25th (or 4%) of its total weight to move it.  For our Land Rover this would equate to approximately 80 kgs or 176 lbs.  However if it were embedded in deep mud and also on a level gradient the total effort required would be ½ (50%) of its weight.  Again for our Land Rover this would equate to 1000 kgs or 2200lbs.  You will also have to factor in any gradient that may be encountered, but we will come to that further on.

The terrain is usually the biggest variable in any calculation of recovery effort requirements.

To make things easy for you I have calculated in the table shown below ‘Various Ground Surface Coefficients’ the effort required to move our two tonne Land Rover on level ground in varying conditions as a fraction of its weight and converted this fraction into Kilogram’s and Pounds for ease of reckoning.
                                                                   
TABLE SHOWING VARIOUS GROUND SURFACE CO-EFFICIENTS

Tarmac Road   1/25th (4%)  of the total weight.  80 kgs 176 lbs
Grass  1/7th (14%)  of the total weight. 280 kgs 616 lbs
Sand (Hard/ Wet) 1/6th (17%)  of the total weight 340 kgs  748 lbs
Gravel    1/5th (20%)  of the total weight.  400 kgs 880 lbs
Sand (Soft/Wet) 1/5th (20%)  of the total weight 400 kgs 880 lbs
Sand (Soft/Dry/ Loose) 1/4   (25%)  of the total weight.  500 kgs 1100 lbs
Shallow Mud   1/3    (33%)  of the total weight 660 kgs  1452 lbs
Bog/Marsh/Clay  1/2   (50%)  of the total weight 1000 kgs 2200 lbs
       

 

A simple calculation will show that the approximate rolling resistance of an undamaged vehicle on a flat surface can be predicted.  An example would be the pull required to move our two tonne Land Rover along a flat surface of wet, hard sand.

If we take the weight of the vehicle and multiply it by the co-efficient for hard, wet sand 1/6th OR (17%) from the table shown above of efforts required to move a vehicle as a fraction of it’s weight, we get the calculation;

    2000 kgs  x  1/6 (17%)  =  340 kg of effort required
 or  4400 lbs  x  1/6 (17%)  =  748 lbs of effort required.


However all surfaces, indeed most of them, are not flat and you will need to include a gradient resistance co-efficient into your final calculation.

If you are unsure as to the type of terrain you are dealing with it is always a good idea to factor in the next highest one in the table to allow you some margin of error.  For example is the sand on the beach hard and wet?  If you are not sure use the percentage for soft and wet sand.  This has decreased your margin for error.  You can always play really safe and use the percentage for soft, dry, loose sand, although it may not actually be necessary, if it gives you less margin for error there is no reason why you could not use it in your calculation.  It is always better to overestimate the pull then underestimate it.

We will now look at the need to factor into the equation any gradient that you may have encountered.  To calculate the gradient resistance co-efficient (part of the total effort required in kilo’s), use the basic principle that for every degree of incline up to 44 degrees, however short the incline may be, the resistance can be calculated as 1/60th of the total vehicle weight per degree of incline.  For inclines of 45 degrees and over, always calculate the gradient resistance as the total weight of the vehicle and don’t forget to include the weight of any load.  For an example of this calculation, for please refer to the bottom of page 14.

Some of the more common incline angles are listed in the table below as well as the calculated resistance in kilo’s (and lb’s) for those gradients.

1/60th of 2000kgs  =  33kgs  Therefore: 

TABLE SHOWING VARIOUS GROUND CO-EFFICIENTS

5 degree incline = 5 x  33kgs the gradient resistance is 175 kgs 363 lbs
10 degree incline  = 10 x 33kgs the gradient resistance is 330 kgs 726 lbs
15 degree incline = 15 x 33kgs the gradient resistance is 495 kgs 1089 lbs
20 degree incline = 20 x 33kgs the gradient resistance is 660 kgs 1452 lbs
25 degree incline = 25 x 33kgs the gradient resistance is 825 kgs 1815 lbs
30 degree incline = 30 x 33kgs the gradient resistance is 990 kgs 2178 lbs
35 degree incline = 35 x 33kgs the gradient resistance is 1155 kgs 2541 lbs
40 degree incline = 40 x 33kgs the gradient resistance is 1320 kgs 2904 lbs
  =   the gradient resistance is    

For any incline of 45 degrees or more it is best to calculate the resistance as the total weight of the vehicle.  (2000 kgs or 4400 lbs)

Again a simple calculation can be done to predict the total effort required to move our two tonne Land Rover up an incline of 15 degrees.

 

i.e.    Gradient  x  weight of vehicle           Which is    15  x  2000 kgs    =    500kgs
                                           60                                                        60

If we combine the weight of the vehicle, the type of surface to be transited and the gradient to be overcome we get the calculation.

Weight of vehicle  +  Gradient (in degrees) x weight of vehicle    =    effort  req.
                                      Surface type                                      60          

OR       W  +  (G x W)    =   2000 + (15 X 2000)          =     effort required
                                                   S       60               4               60        

So using the formula we can predict the total effort required to move our two tonne Land Rover up a sand bank of soft, dry, loose sand with an incline of 15 degrees

2000  +  (15 x 2000)  =   2000  +  30,000    500 Plus 500 =  1000 kgs (or 2200 lbs)
                                  4               60                  4            60      

However if we substitute clay, or marshy bog for the surface (co-efficient of ½) (see table on page 11) and 35 for the gradient or incline, (see table on page 12) using the above equation we would require,

2000  +  (35 x 2000)    2000  +  70,000   1000 Plus 1167 = 2167 kgs or ( 4660 lbs)
                                  2                60              2             60       

USE THE READY RECKONERS BELOW TO FIND THE EFFORT REQUIRED

TYPE OF TERRAIN

EFFORT REQ TO MOVE A 2 TONNE VEH IN KGS

BOG/MARSH/CLAY

(50%)

1167

1334

1500

1668

1834

2000

2334

3000

SHALLOW MUD

(33%)

827

994

1160

1328

1494

1660

1994

2660

SAND SOFT/DRY/LOOSE

(25%)

667

834

1000

1168

1334

1500

1834

2500

SAND/SOFT/WET

(20%)

567

734

900

1068

1234

1400

1734

2400

GRAVEL

(20%)

567

734

900

1068

1234

1400

1734

2400

SAND/HARD/WET

(17%)

507

674

840

1008

1174

1340

1674

2340

GRASS

(14%)

447

614

780

948

1114

1280

1434

2280

TARMAC

(4%)

247

414

580

748

914

1080

1414

2080

INCLINE IN DEGREES

5

10

15

20

25

30

40

45+

 

TYPE OF TERRAIN

EFFORT REQ TO MOVE A 2 TONNE VEH IN LLBS

BOG/MARSH/CLAY

(50%)

2567

2934

3300

3670

4035

4400

5135

6600

SHALLOW MUD

(33%)

1819

2187

2552

2922

3287

3652

4387

5832

SAND SOFT/DRY/LOOSE

(25%)

1467

1835

2200

2570

2935

3300

4035

5500

SAND/SOFT/WET

(20%)

1247

1615

1980

2350

2715

3080

3815

5280

GRAVEL

(20%)

1247

1615

1980

2350

2715

3080

3815

5280

SAND/HARD/WET

(17%)

1115

1483

1848

2218

2583

2948

3683

5148

GRASS

(14%)

984

1350

1716

2086

2451

2816

3155

5016

TARMAC

(4%)

544

910

1276

1646

2011

2376

3111

4576

INCLINE IN DEGREES

5

10

15

20

25

30

40

45+

 

For any incline of 45 degrees or more the gradient co-efficient will always remain constant.  That is to say that as we have noted earlier on page 12, the gradient co-efficient for gradients of 45 degrees or more should be calculated as the total weight of the vehicle, including its load.

Again a simple calculation can be done to predict the total effort required to move our two tonne land Rover up an incline of 45 degrees or more through, for example clay or marshy bog.

2000kgs  (gradient) + 2000 x 50%  (surface co-efficient)  = Total Effort

2000 kgs + 1000 kgs   = Total effort required of 3000 kgs or (6600 lbs)

Or simply add the surface co-efficient weight to the weight of the vehicle