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Off road construction as different from on road construction

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An explanation of Off Road travel, what does it mean?

It means dusty roads, corrugations, rough roads, washouts, millions of rocks.

There is no such thing as a Semi Off Road Caravan, as to go Off Road, as the term implies, is to venture off the black top. This entails a special vehicle but just as importantly a special trailer. Most genuine 4WD vehicles are built to handle off road conditions; these vehicles are different from those that carry the “Soft Roader” terminology.

One of the things we have found over the years is that there is no discrimination in Off Road travel when purchasing a trailer. There is no Soft Road category in trailers. Your trailer has to be set up completely to handle all dirt road travel or you will ruin your holiday completely.

Here are some of the measures you should be looking for when purchasing an Off Road Caravan.

Dust

One of the biggest issues with an Off Road Caravan is dust ingress. It is almost impossible to exclude dust from any trailer as there are multiple entry points. I have to start by saying that there are unseen forces acting on the body of the trailer. Depending on where the hole is in the trailer there will be either vacuum or pressure at that point, both of which will either suck or ram dust into the trailer at speed. It is for this reason that we go to extreme lengths to seal our trailers. All body intrusions and joins are pressure tested at the final QC stage. The door and roof vents required by law for the circulation of air are the major cause of dust leaks as one will cause pressure and the other will cause vacuum depending on where they are placed in relation to one another. It is for this reason that we cover our lower door vents and use a filtered pressure system to exclude dust from the trailer.

One of the beautiful aspects of dirt road driving – you get to see ALL of Australia

We also vent our fridges internally as the external vents seen in most caravans will leak dust. This may seem to be not a problem as the dust is contained in the fridge cavity hopefully. If not it will leak into the internal cupboards. Once in the fridge cavity the dust will settle on the evaporator coils. This means that the fridge coils can no longer dissipate heat, the by-product of refrigeration. This in turn means that the fridge will work harder to maintain temperature and increase your 12 volt usage. For an Off road caravan relying on solar power this is very bad news and will affect the performance of your solar system and battery capacity.

Upon arriving at camp after a long drive the last thing you want to see is dust inside your new trailer. It is for this reason we go to the lengths we do to make our trailers dust proof. All the sealing and dust prevention methods are time consuming and expensive to produce.
Suspension

A truly Off Road suspension has to be very robust and tested over time in the harshest conditions. It also has to have Toe In and Camber adjusters just like your 4WD, this allows for any uneven tyre wear to be adjusted out of the suspension.

On our twin axle Aurora Off Road Caravan we use four completely independent control arms that are non-load sharing. With a load sharing suspension, when the front wheel hits a bump it affects the rear wheel which in turn hits the same bump thus affecting the front wheel. This is four different movements where there should only be two. The non-load sharing suspension is much more expensive to produce as there are more chassis pick up points, but it is far superior in ride quality for the trailer. We also use twin shock absorbers on all our control arms, why is this? Shock absorbers dissipate heat in their actuation, if the heat build-up is too great, the internals of the shock will malfunction due to overheating. This can be most noticeable on Corrugations where the shocks are working their hardest. Some manufacturers using non-compliant single shock systems resort to supplying heat indicators which have to be regularly monitored on corrugations. If they exceed the maximum heat range then you are advised to stop while the shocks cool down. By using twin shocks we halve the stress on each shock absorber and in this way greatly reduce the stress on the individual unit. The twin shock system is used on Off Road racing Buggys and 4WDs which is a similar application and we have used it for the last eight years with excellent results. Some of our owners have exceeded 150,000 km and up to 300,000km in off road travel.

Hot Water System

We use a hybrid hot water and space heating system, not the diesel system that is used in some trailers. The reason for this is that the Webasto diesel space heater when paired with the Truma gas hot water system is much more 12 volt efficient than any other combined unit. Both these appliances are of German manufacture and excellent quality. The diesel hot water and space heating system is a single unit and is very quick and cheap to install. It relies on the hot water to be constantly running in order to provide space heating. However we prefer to use two separate systems as one does not rely on the other to be running. The difference in 12 volt usage overnight can be similar to running a second fridge, which is a very inefficient use of 12 volt power.

With the hot water system you can have a hot shower in minutes and the diesel heater maintains a constant comfortable heat. Gas hot water systems are used by 99% of the caravan industry and are very safe and efficient. We typically get about four weeks use from a 4.5kg gas bottle running both the stove and hot water system. We have two bottles on each model so you have 6-8 weeks supply of gas, more than enough to get lost for a long time.

Solar

Most vans and campers are set up with varying degrees of solar capacity, for off road travel the bigger the system, the better. This is an area where you can never have enough. For those people who want to venture off the beaten track away from the masses, this means no 240 volt outlets are available for the morning toaster. You will be relying totally on the vehicles 12 volt system for your power supply and this is why a large capacity solar system is compulsory. We use very large solar panels, 2 x 150 watt panels on every van; this is about twice what the van will use on a daily basis.

On the Aurora Off Road Caravan we have a 480 watt solar system as standard. All the appliances in the van work from the 12 volt battery supply, the lights, pumps, inverter, fridge, etc and we have a solar/battery performance meter installed in every van to monitor this performance. You may ask why we have such an over powered system? If you encounter some overcast or rainy days then the system will cope with reduced input and still run the van. This is very important for an off road trailer.

Electrical system

As you will be relying on your 12 volt system for everything it is important to have at least two 120 A/H AGM deep cycle batteries, this is the basic minimum for an off road van. More than this and you will be suffering a weight penalty of about 35kg per battery. Lithium batteries are an excellent choice for off road vans as they have a much larger capacity for approximately half the weight. The penalty comes with the price as they are very expensive, however if treated correctly they will last much longer than the AGM battery.

An inverter is also a compulsory item as you need to charge your laptops; phones etc and some people want to watch Television when reception is available. For these small appliances a 300-600 watt pure sine inverter is enough. You can buy a larger inverter but there is no need depending on what you wish to run. The larger the inverter the more cost is involved and they are also very heavy, so again you suffer a weight penalty. As the inverter is remotely mounted, hidden inside a compartment, we need to install a 240 volt RCD as fuse protection in the 240 volt/inverter system. This is more weight and more expense. We prefer to use up to 18 fuses for each van electrical system, this makes finding a fault very quick. If you do blow a fuse it does not affect multiple appliances. These are some of the differences in the electrical system of the off road van. These 12 volt systems are very complex as you can see, unlike the simplicity of the on road caravan which is very cheap to produce, as there is more wiring, more appliances and more labour involved.

Lithium Batteries

We have recently been offering our new range of Enerdrive Lithium Battery Systems as optional upgrades on our Caravans and Super Campers. I say systems because Lithiums must be paired with the correct charging, protection and monitoring systems. They have many advantages over the AGM systems and only a few drawbacks.

They are lighter by about 50% of a similar capacity battery and they are smaller. This means they are able to be fitted into almost any space. A typical weight gain of a 200 amp Lithium battery over the alternative 240 AGM would be about 35 – 40kg. This is the equivalent of a complete spare wheel of your 4WD.

They have a larger capacity for a similar amp/hr capacity. You can use 85% of a 200amp lithium giving you 170 amp/hr, whereas you can only use 50% of the 240 amp AGM giving you 120 amp/hr.

They can also absorb and give off their capacity quicker, giving you shorter periods between charging. This can be a significant advantage on rainy days where the solar charge is quite low, recharging is quicker. This also means you can run larger inverters for small microwaves etc while off road.

They have a longer life cycle. Where AGMs will last about 4-5 years if treated well the lithium’s have a potential life of 10-12 years, up to three times as much life. This in some way balances the extra cost involved in the initial outlay.

One of the drawbacks is the price; we offer two upgrades, a 200 amp system and a 300 amp system. We have chosen the Enerdrive system as all the charging and protection devices are made by Enerdrive and perfectly matched to one another. We are purchasing one system from the one supplier who carries the warranty for the complete system. In this way if you have a problem anywhere, Enerdrive will fix it through their large service network. This is different from most other suppliers where the batteries are purchased separately from the other charging components. Ours is a perfectly matched, warranted system.

The other drawback is the fear of battery failure. If this happens and no lithium’s are available they can be substituted for an available AGM using this system.

380 Litre Water Capacity

We have a lot of experience in providing large water capacity systems as we have travelled extensively in the outback and understand the desire for clean water in arid areas. The spare wheel is positioned not underneath the van but on the rear slide bar rack, thus helping balance drawbar weight. This leaves the underside of the chassis available for four large water tanks. Water is the most difficult commodity to replenish in remote camping so a good water capacity is vital. We can replenish our electricity used with solar but once your water is gone you have to move camp and find a good water supply.

At the front and the rear of the axle of the van we have two 140 litre food grade plastic fresh water tanks shrouded in galvanized steel to protect them from rock damage. Above the suspension is another optional 60 litre tank used for pure drinking water utilizing a separate pump and tap at the sink. This small supply is for pure water which can be used for filling water bottles, teeth brushing etc or as a last resort back up supply. Two jerry cans are fitted standard on the front with provision for two more on the back. These can be used for water storage if required. This gives a massive storage potential of 420 litres of pure filtered water.

In front of these tanks is a fourth 110 litre black water tank used for carrying the waste from the macerator toilet.

If a grey tank is required we can also plumb this into the system. We have also installed a separate system for supplying water from a stream, however this is not recommended as you can never be sure of the water quality and you can become very sick from water born bacteria. This water access system does not contaminate the water tanks, they remain separate. It is recommended that you fill the tanks with town water whenever it is available.

For some people this may seem like a lot of extra weight to carry around; however this gives people the ability to plan their water usage and not be restricted by inferior water supply in remote areas. If you do not need this amount of water then there is no need to use this capacity, it is only there when you need it. If you choose to use the full capacity of the system the water is carried at the lowest point of the chassis and provides excellent stability for the trailer. The drawbar weight is not impacted by complete filling of the system as the tanks are evenly distributed in the chassis. In fact I prefer to travel with full tanks for this reason and the problem that not all towns have good quality water.

We have traveled many times to Coongie Lakes near Innaminka and other very remote areas and have found that there is nothing more relaxing and invigorating than a clean shower at the end of a long drive through our magnificent country.

“Nomad” Macerator toilet system

The macerator system has been used in boats for many years and is a proven system that we have adapted for use in our Off Road Vans. The alternative is the cassette toilet, either electric flush or chemical, but these have a limited capacity, approximately 20 litres, so the time between dumping the toilet is about two to three days depending of course on usage. With the cassette you are also limited in the off road situation where you have to find a dump point. All outback toilets are dry toilets that rely on the bacteria to break down the solids, so dumping a cassette that is full of liquid and sometimes chemicals and liquids is not condoned by locals. Most small outback town have septic systems only so this is also not allowed. You have to find a dump point or dig a hole and bury the contents. This situation is heavily policed in certain areas of Western Australia with very large fines for people caught dumping any cassette toilets as there is so little rain in WA and all the toilets are dry toilets.

The macerator system pumps the waste into a large 60 litre or 110 litre waste tanks, depending on the model, that is vented through a carbon filter, so there is no smell whatsoever. The toilet has a permanent head of water as well, just as does the one in your home and the system uses no chemicals. This large capacity allows you to stay in your remote campsite for longer periods without the restriction of having to find a dump point.

It would have been very simple to install a chemical cassette toilet just like the rest of the industry but we wanted the freedom that only the macerator system can provide. It uses a very small amount of water for flushing as the flush button is a variable flush, you can use as little as you wish, just enough to get the waste away. It is then stored in the large black tank for dumping at a dump point. This system will give you up to six times the capacity of a cassette toilet with far more freedom for your off road adventures.

These pictures were taken in a National Park in Western Australia and are typical of the attitude towards cassette toilets. They do not differentiate if you use chemicals or not.

Generators

Some people think it is necessary to carry a generator as a backup for the 12 volt system and for some people it may be. It is false thinking to set up a trailer to be reliant on a generator as they are banned in most national parks and campsites. It is a better use of money to install a lithium battery system and rely on the 4WD charging the van batteries if they get low on charge. They will charge very quickly and there is no restriction on running your car for a short period in camp. We prefer to use large capacity solar systems installed on all our trailers as described above. A generator may be needed for running an air conditioner for those hot nights in coastal areas.

Generators must also be housed in a suitably vented area or compartment and be well protected from dust intrusion.

Pop Tops

An Off road pop top that holds together over many years of travel is a difficult and expensive vehicle to construct as there are many twisting forces on the body that are not present in the one built for on road travel. If you think of caravan as a box with a solid lid, it is a very strong structure in relation to twisting the box. Remove the lid and it becomes much easier to twist the box. This is what happens in a pop top van, we have to allow for the twisting forces that will be applied continuously to the body over many years of off-roading. We do this by strengthening the chassis and the body but also more importantly how the top is secured to the body when closed. We use six very strong locks and eight internal corner plates to locate the top on the body. In this way we lock the top in place on the body, thus eliminating all twist from the body. With the roof lifting mechanisms there are in total 22 individual points of contact that the roof has with the body, two times more than the on road version.

In a well-constructed Off Road Pop Top the chassis has to be much more robust than the on road version, as all the forces that are exerted from the suspension are carried through the chassis and into the body. This is a very expensive process that adds a lot of weight as there is extra steel members in the suspension and chassis that are designed to cope with the twisting forces before they are transferred to the body. Together with these measures the body has to be specially made to withstand the effects of many kilometres of corrugations and dust and to last for many years.

Drawbar Weight (Ball weight)

We prefer to design our vans around the industry accepted ball weight of 10% as this has proven over time to be the perfect combination for Off Road driving. Having this weight on the rear of the 4wd gives many advantages; all of them involve your safety. Too often we see vans smashed on the side of the road or hear of roll overs of badly balanced trailers. Some owners are ignorant to the fact of significant ball weight, or they have not been informed by the manufacturer that this is necessary for safe dirt road driving. If the ball weight is too light the van will tend to have too much rearward weight and so have an inbuilt instability. If this type of van is driven on gravel roads it can become unstable on some of the very loose gravel corners and road verges. It can also have the same consequences when crash stops are required if wildlife dart out of the bush onto the road.

Having a very stable van on dirt roads is of paramount importance for your safety as there is a greater decrease of traction on the loose gravel surfaces. Too much ball weight presents a very stable van, although at the expense of excessive weight on the rear suspension and tyres of the 4wd, thus presenting other problems such as excessive suspension and tyre wear. It is for these reasons that we build your off road van from the ground up to cope with these inherent dangers.

With our new Matrix Series 4 Off Road Caravan we have been careful to design the trailer with approximately 10% ball weight. The ball weight empty is 10.6% of 1820kg tare, filling the rear tank reduces ball weight to 8.6% of 1960kg, and filling the front tank the ball weight becomes 9.4% of 2090kg. This leaves 310kg for all your gear and a near perfect 10% ball weight as a result.
Stone Protection

This is a significant component of any Off Road van. There has to be suitably designed protection for the trailer components and the 4WD. Firstly the trailer components that need protection are the obvious things like water tank fittings, plumbing pipes and hoses, electrical connections, small pumps etc. Virtually anything that can be damaged by rocks coming from the rear tyres of the 4wd needs to be well protected. This is generally unnecessary with an On Road van so here is another increase in cost and weight for the Off Road Caravan.

We prefer to build our trailers with complete water tank protection using steel shrouds secured to the chassis with large stainless steel rivets. In this way you can never damage a water tank and lose all your water. All other components under the trailer are suitably guarded from the offending rock spray coming from the 4wd.

The front stone deflector is also a very important component of stone protection for the 4wd and trailer. Our front deflectors are designed to present a soft trampoline style of mesh that is angled forward to deflect rocks downward and not back towards the 4wd. With a vertical surface on the front of a trailer the rocks are basically ricocheted back at the rear of the 4wd, sometimes causing the rear window to shatter. These rocks can also almost sandblast the rear panel of the 4wd causing more damage. Some people also use a “Stone Stomper” mesh guard between the van and the 4wd; this is how important the stone protection is. All these measures add weight and cost to the Off Road Caravan.

Width and Tracking

If you are going Off Road the closer the van is to the width and tracking of your 4WD the easier the progress will become. Because the van is travelling in the same wheel tracks as the 4WD, it is not trying to cut new tracks in the sand or dirt surface so progress is not impeded by excessive drag on the caravan wheels. You can also be sure when driving on gravel roads that the van is following your wheel tracks as you pick your way through the sharp rocks on the road surface. This will make driving on sand or gravel a lot safer and more comfortable.

Having the van the same width as the car also means that the van is cutting as slim a profile as possible through the air thus decreasing fuel consumption. There is also no need for mirror extensions which can be very troublesome on rough roads. When you are negotiating tight bush tracks into remote campsites the narrower van is easier to get around tight turns and overhanging trees. There is also a significant weight gain by having a narrower van which also helps reduce mileage. There is no wasted space inside the van as it is designed to be very ergonomic, in this way you are not carrying around useless space. The weight reduction allows us to add other features, such as very large water tanks, solar and battery systems that add value to your remote camping experience.

Spare Wheels

We prefer to carry our spare wheels on the rear of the caravan rather than underneath. They are protected on the back panel and are easily accessible if required (there is a small portable winch available) and they also help balance the drawbar weight, which is a critical factor in Off Road driving. Having the spares under the trailer is a very cheap option as all it requires is a small winch and handle, but in doing so we lose the ability to install larger water tanks.

The rear spare tyre rack also acts as a slide bar assembly which protects the rear body work when encountering a very steep embankment into or out of a creek crossing. This is reasonably common occurrence in Off Road driving as the roads are not always as well maintained as with the blacktop. The rack gives you confidence in this situation knowing you will come out the other side with an undamaged trailer.

The larger water tanks also help lower the centre of gravity of the trailer which creates more stability on rough roads. You will find that the trailer travels better with full water tanks rather than empty ones for this reason. I always prefer to drive with full tanks when going Off Road as the trailer tracks smooth and straight despite the increase in weight. Having the spare under the trailer has the opposite effect on stability than having a full water tank as the water tank is about four times heavier for the same required space.

Awnings

We design our Off Road Caravans and Super Campers to have the very best awning systems available. Some of the features you need in a well-designed awning are good head height, maximum fall in wet conditions, an awning that can be locked back to the van when deployed and one that does not require ropes and pegs to stop it from blowing over the van.

We design our pop tops to have a full length roof that lifts up and not just a partial roof opening. The main reason for this is to achieve maximum head room under the awning in order to supply protection from the heat coming from the awning material and to supply increased levels of air circulation to help keep you cool in hot weather. We do this by using the full pop top body design as it allows for increased height in the van roof. This design also gives very good fall for rain and does not allow ponding which can destroy and awning. There is nothing more frustrating than coming back to camp after a day away and finding the awning collapsed under the weight of water from a rain storm, or worse, the awning that has blown over the van when the pegs have come adrift due to high wind. The awnings we use can also be locked back to the van by a lower diagonal support thus providing security in all situations.

The full pop top design is more costly to manufacture than partial roof opening vans and the awning is also more expensive due to the amount of hardware involved. The full pop top design also allows for much better air circulation inside the van than partial roof opening trailers. On our full height caravans we use the same style awning for all the above reasons.
Warranty

Finally we have Warranty and service. When going Off Road anything can happen and it’s comforting to know that we have in place a very large warranty/service network throughout Australia. We have approximately 43 service / warranty agents Australia wide and this list is growing all the time as we find good quality service centres. These are generally caravan service centres that have a good ethical business and know how to repair and service our trailers. We have a strict service schedule in place which allows for the continued maintenance and care of your trailer.

We also have an upgrade program which we call our Continuous Improvement Plan. If we find that a component is not doing the job it was designed to do we will replace it free of charge, this service extends beyond the warranty period. This program allows us to keep our trailers at the forefront of reliability, the value of which is reflected in higher than normal resale prices.

Conclusion

Having read all of the above you can see the difference in design and components that go into the construction of a high quality Off Road Caravan or Super Camper. You can also appreciate that the processes involved require more investment in labour and materials than is required for the blacktop van. Our Vans have to perform for years in punishing conditions and have to be at the peak of design and ergonomics in order to justify the investment. It is for the reasons above that our trailers attract the best resale prices in the industry.

When you use the Caravan for its intended purpose the quality becomes apparent.

Steve Budden

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