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Making the all-terrain sledge

Introduction

Even by my standards, this is a big and complex project. The only reason it is detailed here, is that I can't live without it. The weight could possibly have been cut by about 1 Kilogram, but at the moment the whole thing is sturdy and water-resistant. Solo trips require a different mindset: if you are deep in the Woods alone, and something breaks, your pals will not band together to help you out. For this reason solo gear tends to be a little heavier, and less likely to self-destruct. You are welcome to build 'something similar', but if it lands you in trouble, it's not my fault.

The Drum

A 150 litre drum with lid fitted is about 36 inches tall, and the lid is about 14 inches diameter. The drum, lid and ring together weigh about 8 Kilograms. The photo shows the front and side views of the drum.

You will need a trade supplier of secondhand industrial plastic drums, and the Yellow Pages is the best place to look. This will be a 'drum laundry', where steel and plastic drums for industry are washed out, then sold clean, for material suppliers who find new containers too dear. You need a blue high density polythene drum, of 150 litres capacity, with flat sides and a small black polythene lid. A washed-out drum will still smell of its previous contents. Industrial soaps, detergent paste, or surfactants are the best, since all are virtually non-toxic. Phenolic resins, which stink, are best avoided. Drums that hold phenolic are rare, and are hard to resell, so your supplier may be tempted to offload one on you. Drums that have held dyes are not too bad, unless strongly stained inside and out. The drum should not be dented or deeply-scored. Make sure the gasket inside the lid rim is in good condition, along with the top rim of the drum. The lid should fit snugly, and seal down with moderate pressure on the handle of the sealing ring. If the lid or ring needs to be thumped with a mallet, it will be no good out in the snow. Try another lid and ring, and offer the supplier more for a good one if you have to. Secondhand drums are cheap, and it is worth paying considerably more than trade price for a really nice example.

The drum laundry only does a quick job of cleaning out. Be prepared to spend most of the afternoon scrubbing the drum out with methylated spirits (industrial alcohol), detergent, and water, then a mix of all three. Most of the smell of the previous contents will have gone when you finish, and the remaining whiff will fade away over a year or so. When you have a sparkling drum with a well-fitting lid, you can either carry on, or use it to store dry sleeping-bags in dirty sheds.

The wheel and axle

Engineers' hardware shops, or wheel and trolley specialists, sell spare wheels for hand-trolleys. The red high density polythene wheel is about four inches wide, and about four and a half inches in diameter. It comes already fitted with an inflatable tyre and tube. The tyre spec on mine is 4.10/8.50 - 4. This is almost a balloon tyre, with a light block tread. Maximum tyre width inflated is about 4.2 inches, and inflated diameter is 10 inches. These are the fat, pump-up tyres you see on hand-trolleys everywhere. The bearing housings in a trolley wheel are offset, so one housing sticks out beyond the rim of one side of the wheel, while the other is recessed in from the rim, almost at the centre of the wheel. This design allows the wheel to mount on a short stiff steel rod, which is one side of the trolley axle. The bearings are cheap pressed metal ball-bearing sets, that cry out to be replaced with precision-ground industrial equivalents. I will resist temptation, until the cheap ones fail.

Mounting the wheel, and bearings, on a shaft is not straightforward. If you imitate the trolley makers, and just push the bearing assembly onto a steel rod, with a split pin and washer, you take pot-luck as to whether the ball-bearings spin as they should, or whether the bearing sleeves rotate on the rod, increasing tolerances, and wearing fast. The wheel is going to take a hammering on the sledge, and bearing mounting like this is not adequate.

If you cannot turn up a short axle yourself, get a turner to make one for you. I know the bearing sets are only pressed into a plastic wheel, but this makes rigid mounting of the sets on the axle even more important.

Changing units quickly, my axle is 71 millimetres total length. There are 25.4 mm to the inch. The steel axle has a short 12 mm wide section, where it mounts on the aluminium stub, and this section is 40 mm in diameter. A long hole is drilled down the centre of the axle from this end, and tapped 8 mm metric, or the equivalent in Whitworth or UNC. Provided the aluminium stub is sturdy enough, a length of stainless 8 mm allthread can take enough torque to firmly locate the 40 mm diameter mounting surface.

The photo below shows the axle held by the allthread to the end of the aluminium stub. Note the axle terminates flush with the stub, and an aluminium turned cylinder of the right dimensions (see later) has been forced into the stub to provide a rigid end. The other end of the stub can be seen firmly welded to a piece of plate, which is held to the reinforcing on the base of the drum by four studs. In the free end of the axle is an 8 mm socket head screw, which tightens up to grip the wheel bearings. The turned aluminium sleeve inside the wheel, between the two wheel bearings, is not shown.

The rest of the 59 mm length is carefully turned down between centres, until it is a medium push fit through the two bearing sets. The final diameter is close to 16 mm for my bearing sets. You can do the final fit adjustments with a strip of emery paper. Next you need to take precision measurements of the bearing sets pushed into the wheel, and calculate the exact distance between the inner edges of the sleeves of the two sets. Turn up an aluminium sleeve, that slides over the axle shaft, of just this length. I cheated, made it longer, and did a few trial assemblies, removing a little each time. Finally drill and tap the small end of the axle shaft, also 8 mm metric or equivalent. Note the distance between the shoulder and the axle end will correspond, on your wheel, to slightly less than the distance between the outer edges of the bearing sleeves. This will allow for the inevitable closing down as the aluminium sleeve is compressed.

Assemble, in the right order, the axle, one bearing set, the aluminium sleeve, the wheel, the other bearing set, a thick washer and an 8 mm socket head screw or equivalent. As you tighten the socket head screw, the bearing sets align in the wheel and on the shaft, until the aluminium sleeve is locked between the two bearing sleeves. Your two cheap bearings are now perfectly mounted. If they are not, carefully trim down the axle dimensions until they are. Difficult? yes. Impossible? no. Any professional fitter could do it in his sleep.

The hardest part of the project is now over. The wheel will not feel perfect, as it rotates on the axle, since the bearing sets are not industrial, but there should be only be a small amount of free play. The odd 'tight point' is also to be expected, and will 'run-in' with use. After five long trips, the wheel on my Mk 2.5 is running perfectly.

Cut off a few inches of 8 mm metric stainless allthread, or equivalent. Lock two nuts on it, and wind it hard into the tapped hole in the axle.

The aluminium stub

This is made from a 40 mm square hollow aluminium extrusion, matching the diameter of the axle end. A 7 inch length is enough to allow the tyre to comfortably clear the base of the drum. Falling down from crossing a tree, the wheel can deliver a real wallop to the end of this stub, via the short rigid axle. 40 mm square extrusion can easily resist heavy impacts, but how the axle is fastened to the end of the stub is critical. Drilling a hole in one side of the square stub, pushing the allthread through, and locking it with a nut and a few oversize washers, is not adequate.

At the very minimum, drill a corresponding hole in the other side of the square stub. Pass the allthread through both, screwing on extra nuts, and adding big washers where appropriate, as you do so. Tighten the washers and axle down as before, then lock a pair of nuts and included washers down on the allthread, where it passes through the other side. This may give you enough strength.

Correct aluminium stub / short axle mounting.

Note: The instructions follow a logical order, but the section following this (welding) is best done first, since a stub with a closed end is much harder to clamp up for welding.

This is lathe work again. Turn a short length of round aluminium bar down, until it just pushes into the end of the hollow extrusion. Part off about 40 mm of this turned bar, put it back in the chuck, and take a little off the end, until it just starts to fit sideways into the hollow extrusion. Using the lathe, drill an 8 mm hole right down the axis of the bar. Push the bar section sideways into the top of the hollow extrusion, and tap it down with a hammer until it is just inside. Since it is an each-way fit, it will align, but you may need to hit it quite hard.

Once the bar section is in position, drill by eye a 5 mm hole through the side of the extrusion, so it ends up inside the 8 mm hole already drilled through the bar. Use a small round file to open up the hole until it matches with the 8 mm one. You can now electric-drill down through the 8 mm hole and through the other side of the hollow extrusion. You now have a solid braced end to the stub. Push the allthread sticking out of the axle through the 8 mm hole. Screw on a single nut and washer, and tighten down. The excess allthread can now be sawn off, and the cut filed smooth. There is now a maximum-strength joint between the aluminium stub and the short axle.

Welding the aluminium stub mounting plate

Maximum strength is still required at the other end of the aluminium stub, which plainly has to terminate in some variety of plate, so that it can bolt to the bottom of the drum. I considered various options, all tricky to do, prone to failure, and likely to work loose. The only answer was welding, and I found a local alloy welder, to do the job for me.

I faced off the end of the extrusion in the lathe, so it was accurately square. I cut with a hacksaw, a 5 inch square piece of 6 mm (1/4 inch) tempered aluminium plate, and drilled an 8 mm hole right in the centre. Two nuts held an odd length of 8 mm allthread firmly in this hole, long enough to poke out of the top end of the stub. Giant specially-made washers provided alignment, at both ends of the stub. I screwed down a single nut, on the top of the stud, and it was firmly mounted in place, ready for welding.

Because accurate clamping is the hard bit, the welder charged me very little to lay down a thick fillet on the four-sided joint. I cleaned up the weld with a coarse round file, drilled four holes accurately square in the corners, not too close to the edge, and rounded the corners. This completed a wheel assembly that normally lives off the drum, and is bolted on when I arrive in the mountains. Despite frequent impacts the plate/wheel assembly remains as straight as when it was made. The tyre, wheel, axle, stub and mounting plate weigh 2 Kilograms total.

Bolting to the drum base

The drum is high density polythene, around 5 mm thick. The hase is flat, apart from two moulded-in hand recesses, and a centre ridge line where the two halves of the split mould meet. The base is not rigid enough to directly bolt the plate/wheel assembly to it. A reinforcing plate is needed, and to maximise space in the drum, as well as avoid the hand recesses, this plate has to be mounted on the outside. I would guess 9 or 10 mm thick marine ply would be the absolute best material for the job. This is expensive stuff, and I did not fancy the varnishing, upkeep, and slow deterioration possibilities. I had plenty more 6 mm tempered plate, so made the base reinforcement out of this. Like the plate/wheel assembly, it is on the heavy side, but has not bent with use. Water and wet snow are no problem, of course, and the base needs no upkeep at all.

Maximum strength would demand the reinforcing extend over the whole area of the base, to use all the edge-mounting area. This was not required, so I reduced the width of the reinforcing, which cut both the amount of aluminium plate required, and the weight. Mounting the plate was a 'quick and dirty' job. I cut it to shape with a hacksaw, and filed rough areas smooth. I then drilled one narrow edge locator hole through the aluminium into the drum, removed the aluminium, and widened the drum hole to clearance for a big self-tapping screw.

I widened the aluminium hole to the self-tapper cutting size, pre-cut the thread with a spare self-tapper, then put the aluminium back on the drum base. I screwed a self-tapper into the aluminium from inside the drum. This located the aluminium correctly at one point on the drum. All I had to do was repeat for a second hole, and I had location.

I located a total of 8 self-tappers, to hold down the reinforcing plate. Inside the drum each one passed through an oversize washer to avoid distorting the polythene. The screws were too long, and I cut off the excess on each, and finished off the rough cut on each with an angle-grinder. I could have sealed each screwhole with Silastic or similar, if I anticipated taking the drum through deep water. The aluminium plate was now mounted adequately on the drum, with minimal effort. After an Autumn and Winter of heavy use, it has not worked loose.

I put some blobs of 'blu-tak' putty-type adhesive on the contact area of the welded plate/aluminium stub assembly. The wheel was firmly bolted on the stub. I tapped the plate down on the reinforcing aluminium, shifting it round until the wheel was central on the end of the drum, and facing at right angles to the snow sliding surface. I then hammered down the plate to get maximum adhesion, and took the wheel off.

I electric-drilled through the four 8 mm holes, only pushing far enough to cut small drilling centres into the plate surface. Everything was then dismantled, and I machine-drilled four true holes through the marked centres before tapping them with an 8 mm thread. Tapping was started in the drill chuck, to keep the threads precisely at right angles to the surface.

I then put the reinforcement back on the drum, and used a smaller drill to run though the four tapped holes into the drum, without damaging the threads. Off came the aluminium once more, and I oversized the four new drum holes to ample clearance for 8 mm socket head screws. Back went the aluminium, all the self-tappers were tightened, and four socket head screws went from inside the drum, through pancake washers, and were moderately tightened into the aluminium tapped holes. This further located the reinforcing, as well as locking the screws, so the protruding studs were both rigid, and resistant to rotation. Work on the bottom of the drum was completed.

The protruding studs were long enough to drop the wheel mounting plate over them. I tightened four nuts and washers down on the plate, and the wheel was firmly mounted on the drum. The whole wheel assembly is normally stored inside the drum, and only mounted when the car trip is over, and the hiking/skiing begins.

The drum lid.

Starting from the centre of the lid, and discounting odd hole-filling screws, two aluminium blocks can be seen, into which the handles are screwed. The two outer assemblies are the long arms to hold the towing skirt. On top of each arm is a ski-rack. The inner black high density polythene strips have small recesses cut in them to locate the skis. The outer black objects are the coiled-up Velcro sticking straps that hold the skis and poles down to the racks. The handle mounting blocks may look like overkill, but they are not.

Reinforcement

The gasket/sealing ring system used on these industrial drum lids really does work. The locked-down joint can resist much deformation, so all that has to be done is to reinforce the inside of the flimsy-feeling lid, and it will carry surprising loads.

Because the reinforcement is inside the lid, resistance to rain and wet snow is not so important. I used half-inch thick exterior grade plywood, which is cheap. A circle just over 12 inches in diameter fits neatly inside an internal ridge on the lid. The lump of ply I had handy was just too narrow, so I have a couple of small flats on the circle. I originally used 8 fat self-tappers running into the ply spaced equally around the ply rim to provide edge mounting, but four of these became redundant. They were replaced by locating points for the combined ski rack and towing skirt holder.

The photo shows many other screwheads running through the top, but this lid has been used for umpteen variants over the years, and most of these just plug holes to keep the water out. A few self-tappers are a good idea closer to the centre, just to stop the inside of the lid from flapping up and down.

The handles and mounts

Much can happen to a long handle in the way of rough treatment. The handle mounts must transmit this to the reinforced lid, without cracking, bending or working loose. I decided that solid mounting blocks were the only way to go. If the blocks had faces at the correct angle, there would be no need to bend the handle tubes. Once the tubes were straight, they could be screwed in and out of the blocks by hand, with no tools required or screws to lose, to quickly change the configuration of the sledge. The blocks would have to be hand-crafted from solid aluminium, with surfaces that were really flat. They would be just large enough to attach to the reinforced lid by means of a tapped 8 mm metric hole at each corner, with space allowed for big spreader washers on the plywood.

Making the blocks

I will emphasize, you may be pulled-up at this point. The blocks took me about a day and a half to make. A retired engineer, with time on his hands, might do them for you, but otherwise you will have to cut them slowly out with a hacksaw, and learn how to file them to a precise shape. I cannot cover all the techniques here in detail. This is the sort of thing apprentices make at College, to demonstrate they can construct to size, without using a machine. If an engineer cannot make them for you, he might give you a few tips on how to start.

The blocks look like rectangular houses of the sloping-roof type. At the top of the 'roof', the two sloping sides meet at 90 degrees. The long shallow sloping side is at 36 degrees to the base of the 'house', and the eaves of both roofs are at the same distance from the base of the 'house'. The base of the 'house' screws to the drum lid, and the handle tube screws into the centre of the shallow sloping side.

The 'house' is 50 mm wide, and 46 mm deep. Each eave is 15 mm above the base. The top roof line is 39 mm above the base. The shallow roof is 36 mm by 50 mm, and accurately flat. The steep roof is 26 mm by 50 mm. Precise dimensions are not essential, as long as the block is true, and not skewed, but don't make it much smaller than this. It might be possible to use high density polythene, or polyacetal, to save weight, but I would not take the risk.

Cutting-out techniques

You need a block of solid aluminium 50 mm square (2 inches is fine). A four inch length is more than enough. I was really clever and got an offcut only just long enough, worked from the centre outwards, and saved cash and effort. If you want to do the same, take these instructions with a pinch of salt, work out the exact dimensions, and continue from there.

Allow some waste at each end, unless you are being clever, and scribe a line across the block at an angle of 54 degrees. This corresponds to the 36 degree slope on the shallow roof. Square the ends of the scribed line across the block carefully, to the other side, and scribe a corresponding line, across the opposite face of the block. Unless you have your front and back lines crossed, you have now defined all four sides of an angled cut. Slowly work round the cut with your hacksaw, taking about a millimetre out before shifting to the next side. Just go round and round. If your initial scribing is true, you will make a true cut. As the cut deepens, you can take more out, and the whole process accelerates. After a good while, you will have two halves, and each half makes a 'house'.

Each of the cut faces forms the base of a 'house'. They will need cleaning-up, how much depending on your hacksaw skill. You must have a 'dreadnought' file or similar, which is an ultra-coarse specialised aluminium file, with big curved cutting blades rather than teeth. This slices off aluminium at a great rate. Clean up the two cut faces with the file. Use your square to make sure the cut faces are true to the other edges. There will be a bit of wobbling, if you press the cut faces together, but if the rest of the block aligns, so it looks more or less like an uncut block, you are ready for the next step. If the block will not fit together properly, your cut surface is not correctly angled, and much more file work will be required.

Rub a thin layer of engineers' bearing blue on a piece of flat glass or similar. Rub one of the cut faces of the block on the glass, and blue will transfer to the high points of the face. File down the blued high points a fraction, and do another rub. Repeat until the cut face is flat enough for you. For engineers reading this, and going purple, yes, this is the incorrect method of using bearing blue, but it is good enough for this job. If all is going well, you will be gawping at two machine-flat faces, and wondering how you did it.

You are working on the 'sharp ends' of the two cut pieces. The end edge is trimmed back, so it forms a face, at right angles to the laboriously-flattened cut face. This face runs from the base of the 'house' to one of the two main eaves. Cut as close as you dare with the hacksaw, then trim with the file, again using the square to check for truth. You want a base to eave height of 15 mm. Once this is done, use your blued piece of glass once more on this filed face, and get it tolerably flat. Repeat the whole paragraph to put a face on the other cut piece.

Measure up from your newly-made eave 26 mm, make a scriber mark, and square a scribed line from this mark, across the face of the block. Use the square to continue scribing the line round the other three sides of the block. Note you have just defined the steep roof. Hacksaw just outside the scribed line, to cut off the block. This is another precision cut, so keep working your way round, just like the 54 degree cut. When the finished cut is trimmed, cleaned and blued flat, you will have defined the shallow roof. The steep roof is the flat side of the block, so needs no flattening. Repeat the whole paragraph to cut off and define the shallow roof on the second 'house'.

All that is left is the second eave, also at right angles to the base. Cut a bit off with the hacksaw in the right place, and trim back with the file, until the 15 mm high second eave is formed. Blue the eave flat, and repeat for the second 'house'.

Each 'house' is 50 mm or 51 mm wide, depending on whether the block was 50 mm or 2 inch. As well as the steep roof, both of the 'house' sides are flat, since they are original block sides.

The cutting of the two mounting blocks is finished, and they will look good. Attention to detail is not only cosmetic. Unless the faces, especially the shallow roof, are flat and true, the handles will not work properly.

Hole drilling

The handle-mounting hole in the centre of the shallow roof, on each block, is the critical one. Hole positioning is not critical - just scribe a couple of intersecting lines from the two pairs of corners, and punch-mark where they cross. What is absolutely critical, is that the centre hole, and the 8 mm or equivalent thread cut in it, are both at right angles to the surface of the roof. Take it to an engineer, or be prepared to adjust, pack and mallet-hit your drill and drill vice until you can put a hand-square against a mounted drill, and confirm that the face of the shallow roof, with the 'house' held in a drill vice, is at right angles to the mounted drill, in all directions. You only get one chance. When you are sure, drill right through the block from this face, only putting in your pilot drill 2 mm deep. The drill size will be tapping size for 8 mm metric or equivalent. The drill needs to be sharp, with the cutting angles correct as well. You may need three weeks or so, to work out how to sharpen a drill right.

Tapping

Once the hole is drilled, mount your 8 mm tap in the drill chuck, assuming the drill vice is clamped down, as it should be. Unplug the drill from the Mains, set the speed-changing belt to slowest, and hand-rotate the motor-driven pulley, while you hold the tap down on the drilled hole, with a squirt of oil for lubrication. You can work the pulley to and fro, as in normal hand-tapping, but sooner or later the tap will start rotating in the chuck jaws. The thread alignment is established by then, so take out the tap, put it in a tap wrench, and finish off the thread cut by hand. Go as deep as the tap will allow.

The lid mounting holes

The centres of the four holes through the base of the 'house', are at the corners of a rectangle 32 mm by 31 mm. These are drilled and tapped 8 mm metric (or equivalent, as always), with no special requirements for accuracy or super-vertical holes. This provides a generous 'meat' allowance beweeen the holes and the edge of the block. Trim the block down at your peril.

The handles

The handles are light gauge drawn aluminium tube, and each is 25 mm external diameter, or one inch. The handle length on mine is 20 inches, although it is advisable to leave them longer, and trim them back after trying out the finished wheelbarrow. Each tube is faced off in the lathe, but the hard work is making a specialised turned plug, for each handle tube.

The photo shows the plug after fitting in the end of a handle tube, with the locking hole drilled, and a short small self-tapper screwed in each side

This plug has an 8 mm metric thread length through its centre, allowing the handle to screw into the roof of the 'house'. The wide flat from which the screw emerges is forced against the flat shallow roof surface, as the handle is screwed in tight. This will only happen if the two tapped holes in the mating parts are accurately at right angles to the mating surfaces. If the surfaces butt correctly, they take all the load-bearing stresses, leaving the 8 mm studs to just hold them together. They feel adequately strong, but there is still a squeak or two, if you are wheeling a loaded barrow fast across rough ground.

Turning the plugs

You need six inches or so of round alumunium bar, 37 mm or greater in diameter. I had none, so I dropped a little more 50 mm square bar into the four jaw chuck and turned it down to round. Total length of the plug is about 55 mm, so there are no rigidity problems while turning. Reduce the diameter of 60 mm of the bar down to around 36.5 mm. This looked strong enough to me, but tastes vary.

Take a faced-off handle end, and run a Stanley knife blade, or the business end of a large new screwdriver, around the inside of the end of the tube, to take off any burrs. You will overshoot when fitting if this is not done carefully.

Reduce the diameter of the end 42 mm of the bar. Try the deburred handle tube on it frequently. The object is to get the bar down to a size that will drive up the inside of the handle tube, with no slack. Once you can push and wiggle the handle up about a quarter of the length of the bar, the diameter is right. Wiggle it slowly off again. Part the plug off from the chuck, leaving a 36.5 mm section about half an inch wide. This is ample for rigidity. Repeat this sequence to make a second plug for the other handle. Drawn tube fluctuates in internal diameter, and your two plugs should be individually tailored for the two handles.

Mount a plug in the three jaw chuck, with the 36.5 mm shoulder against the jaws. Drill out a tapping size for 8 mm metric or equivalent. Again tap alignment is critical, so get as much as possible of the thread cut while holding the tap in the lathe drill chuck. Finish the tapping with a normal tap wrench. Go in as far as you can. There will still be partially uncut thread, for the stud to bite into.

Support the other end of the handle tube on wood, and drive a plug right up to the wide section. Repeat for the other handle. Despite the tight fit, repetitive flexing will work the plugs out during use, so they need to be locked. I could have used epoxy, or even super-glue. Both presented assembly problems, as well as being impossible to get apart again. I put the plugged tube into the vice, and with an electric drill, put a hole about 10 mm back from the handle/plug joint, running right through the tube and plug, until it came out the other side. Luck was with me, and it was near enough central and perpendicular to fool the eye. I forced a short slim self-tapper into each end of the hole, solidly locking the tube and the plug together. The self-tappers were too short to poke into the 8 mm internal thread, so it remained clear. I repeated the operation to mount and secure the second plug.

With the plugs locked in the ends of the handles, hold this end of a handle in a vice. Cut off a few inches of 8 mm stainless allthread and lock two nuts on it, Wind the allthread into the plug until the thread seizes. Hacksaw off the allthread, so there is about 17 mm poking out. It is worthwhile slipping the handle back in the lathe chuck, and facing the end of the allthread off perfectly, so it engages easily with the thread in the 'house'. Repeat for the second handle and plug. Apart from final length adjustment, your screw-in handles are completed.

The towing skirt

The photo shows the towing skirt hanging vertically from the lower bar, that has been bolted to the towing arms on the drum lid. One of the two long Velcro-secured ski straps has been undone.

The towing skirt has been a standard fixture in many of my oversnow designs. It derives from the large bearskin, or similar, that was used to pull dead animals, or bundles of firewood, over deep snow without the need of a sledge. The front of the bearskin is tensioned by the pull, and progressively packs the snow as it slides forward, so the load slides along a packed strip of snow rather than sinking into it. Almost any short fibreglass or polythene pulk will give trouble in soft snow, jerkily sinking into the snow, so not even the aluminium towing tubes will smooth things out. When the snow is fresh and sticky, such designs will push great lumps of snow in front of them as well. Even if you make nothing more of the sledge, using a towing skirt, ahead of existing pulks, sorts out a great deal of trouble. If your pulk glides rather than bucks along, rope towing becomes much more acceptable, and there is a good deal less to stow in, or on, the car.

The material used for the skirt is clear low density polythene sheet, from an industrial plastics supplier. Thickness is one sixteenth of an inch, or 1.5 mm. Width of the skirt is 16 inches, and this figure is quite critical. The total length of the polythene used is 34 inches. If you shorten it more than 6 inches, and tow through deep light powder, you will be in trouble. Snow that flows round the legs just below the knees, while just the ski tips are visible, is a great rarity in Australia. Basically, all you need is two 16 inch lengths of wood, one tacked to each end of the strip. One bolts to the sledge, and two 33 inch towropes go from the other to the skier's waist.

In practice, things are more sophisticated. Wood will get wet, and deteriorate, so the strip that contacts the sledge is made from high density polythene. The strip is 1.5 inches wide, and 1 inch thick. I had antistastic black grade available, pre-cut to a strip, so used it. Again, an industrial plastics supplier will saw it for you. If you really do like complexity, a light drawn aluminium tube 40 mm diameter would save weight, but create construction problems.

The photo shows the front end of the polythene strip sandwiched between light extrusions. Each end screw holds a webbing strip, which anchors the end of one short towrope.

The towrope end can be much lighter, and extra weight here can upset the whole tow. I did not want to use wood, so sandwiched the end of the skirt beween two lengths of half-inch square hollow aluminium extrusion, 1.6 mm thick. Close-spaced long 3 mm metric screws ran from one extrusion, through the skirt end, and into the other extrusion. This has been 'make and forget' and the whole assembly has given no trouble.

The towropes are short at 33 inches, since all of the skirt is towing length. They finish in loops. Strongly hand-sewn on the padded hip belt of my pack, are two loops of flat nylon webbing, the same width as car seat-belts. I fit two short cords to these loops, and the other ends of the cords terminate in two slim screw-up steel oval rings. These assemblies live on my pack all Winter. I just drop a towrope loop through the oval ring on each side, and screw them up, making a perfect joint in seconds. The sewn points on the waistband take the force, and towing is comfortable.

Mounting the towing skirt

Obviously maximum rigidity of the high density polythene strip, at the sledge end of the towing skirt, is secured with a two-hole mounting. The holes are not right at the ends of the strip, but set in a few inches, to minimise the space between them, while still keeping the outer sections stiff. I settled on a spacing of about 260 mm or just over 10 inches. Note that the holes were not drilled now - I made the towing skirt mounting, fitted it to the lid, complete with fastening bolts for the skirt strip, then measured the bolt separation, and drilled the holes in the strip accordingly.

Any time a towing skirt is fixed to a lower strip and dragged along the snow, scraping of the heads of the fixings against ice, fallen timber, and the odd lump of rock, has to be taken into account. I mounted the strip vertically on the drum lid, that is at right angles to the towing skirt. I rounded off one of the four hard edges on the strip (a wide sharp wood chisel is best) so that the skirt was fastened well clear of the snow, then wrapped the skirt 90 degrees round the radiused corner, before it contacted the snow. This had many advantages - the slight spring of the skirt on the bent corner allowed it to ride over rock tips etc without gouging.

The photo shows one side of the towing skirt lower bar fitted to the towing skirt mount. The polythene strip is bent forward round the radiused edge of the bar ready for towing across the snow. Note the self-tappers, part of a whole line that secure the strip to the lower bar.

Making the towing skirt mount

Any means of hanging two mounting points off the edge of the drum lid, so they end up in the right place, is acceptable. These points have to withstand much pulling and jerking, so they have to be strong. I wanted them on the lid, rather than cobbled onto the drum. The main trouble is that the lid is recessed, so any mounting arms have to be spaced above the recess, to clear the rim. I had some hexagonal cross-section brass handy, so turned up four spacer nuts 25 mm long, and tapped them 8 mm metric right through. Two spacer nuts were mounted each side of the drum lid, and held down firmly by 8 mm socket head screws and big washers on the inside. For summer use, the rest of the assembly is not required.

The support arms were made from 20 mm square hollow aluminium extrusion, 3 mm thickness. Holes were drilled at the right separation for bolting down to the spacer nuts, and I did the normal 'overkill' by turning up cylindrical spacers to jam down the inside of the square extrusion. Look at the wheel mounting on the aluminium stub for details of a similar process. This made sure of maximum strength at the mounting points, and eliminated any risk of the extrusion buckling under excessive tightening. The arms were bolted down onto the 25 mm spacer nuts before cutting to length.

The arms now set the 260 mm spacing for the skirt strip mounting. Arm length is critical, since that sets the tilt angle of the drum relative to the compressed snow generated by the skirt. In practice an arm length, such that a line joining the two mounting points just grazes the outer lip of the lid, is ideal. I drilled 8 mm clearance holes in the front sides of the arms only, since stresses are minimal at this point. I could then cut and smooth the arms to length. Into each hole went a length of 8 mm stainless allthread, locked by nuts internal and external to the extrusion. I measured the precise distance between these two studs, then drilled holes in the strip mounted on the skirt to correspond. I dropped the strip onto the holding studs, tightened up a nut and washer on each to hold it down, and cut off the excess stud length. This completes the towing skirt mount.

The ski rack

Long ski trips established that the system had no major problems. There was plenty of terrain, only half-covered with snow, to cross. The skis mounted alright, on the arms holding the towing skirt, while travelling on foot. The bother of using a couple of hook elastic straps, and the wiggling of the skis on the arms, was getting to me. Safety was also a consideration. Under storm conditions I risked losing an eye, if I got stressed-out enough not to fasten a hook properly. I plainly would be using this system for a long time, so I built a proper lightweight ski-rack onto the two arms, with long captive Velcro closure straps. The skis and poles now lock down in seconds, no matter what the weather. Once locked down, they are firmly in place, and can be forgotten about, apart from wriggling them through trees, gates and bushes.

I will not give full details for the rack, but much can be learnt from the earlier close-up photo of the drum lid. I used two strips of aluminium angle, and two cut-to-size strips of black high density polythene. The ski slots were cut with a hacksaw and a wide sharp chisel. The aluminium angle dropped onto the skirt support arms, with two holes that aligned with the 25 mm spacing nuts, so the holding socket head screws had an extra job to do.

I extended the studs holding the high density polythene strip to the angle, and with 25 mm long spacers parted from small aluminium tube, and washers, made a 'spool' at each end of each ski-rack. On one spool each side dropped a 41 inch length of 25 mm nylon braid, held by a sewn loop. Velcro type hook and loop, in just the right place on each side of the strip, made a ski-holding strap that could be wound round the skis and poles a few times, to grip them firmly. Did it work - I'll say!. The captive straps really have made using the whole design a positive pleasure.