Until Doc Brown’s “Mr. Fusion” machine from theBack to the Future movies becomes a reality, or true long-distance remote EV travel is viable, we rely directly on fossil fuels and their supply infrastructure for our overland adventures.
There is no substitute, and likely never will be, for the fact that humans need water, and a lot of it, to keep moving through the world every single day.
Fuel to drive, water to stay alive.
Managing fuel and water supplies are crucial and related concerns for planning wilderness travel both for short and long distances. Their importance is obvious, but the actual details are often hard to get a handle on. Our friends from Expedition Overland have some key insights on some of the challenges they present.
Why are they related? A gallon of gasoline weighs 6.3 lbs. A gallon of diesel weighs 6.9 lbs. A gallon of water weighs 8.3 lbs. From a weight density standpoint, there is hardly anything else you can carry with more impact on your vehicle. Each gallon of gasoline, diesel, or water occupy approximately 0.13 cubic feet of physical space. They all require specialized containers and handling for your safety, and for accessing them easily. Running out of either fuel or water will end your journey very, very quickly.
There are several limitations and opportunities that we need to consider when mapping out our water and fuel needs.
The first is supply - the weight and space required for transporting these trip-sustaining liquids should not be underestimated. Every vehicle on the road is assigned by the manufacturer a maximum GVW - gross vehicle weight. This is the engineered maximumtotal loaded weight of that particular vehicle. It’s a measure that has both legal and mechanical consequences. It takes into account a wide range of engineering variables such as braking, suspension, chassis strength, engine power, tire rating, transmission and axle strength, and the weight of the vehicle itself.
Any weight added beyond the vehicle’s base weight is referred to as payload. Stretching your payload beyond the GVW - with people, gear, fuel, and water - creates stress and dynamic effects that the vehicle may not be originally designed to handle. In many countries, it’s actuallyillegal, and with serious consequences, to exceed your GVW while driving on public roads.
GVW varies widely across vehicle platforms. At 1,150 lbs, my old XJ model Jeep Cherokee that was my first real overland rig had a relatively low payload capacity for an off-road oriented 4x4. In contrast, my current adventure vehicle, a Land Rover Defender, is not that much larger than the Jeep, and has considerably less power. It has a payload of over 1,500 lbs. Upgraded brakes and suspension can increase your payload capacity, but that’s a hard calculation to arrive at accurately for the average overland enthusiast.
Of course, given the weighty nature of fuels and H2O, any that you may carry can affect the performance of your vehicle in several ways. The first is simply on-road and off-road capability. Over-stressing your rig mechanically by overloading it can lead to breakdowns - whether it’s burning brakes, tire failure, clutch failure, broken axles, or snapped suspension components, excess weight makes these outcomes more likely, especially in rough terrain. The second is efficiency. Every pound you add to your payload decreases your fuel range, which limits your adventure and increases stress on you and your peace of mind.
So, what to do? There are a number of ways to tackle the supply problem with proper attention to the demands on your fuel and your water when you’re on the road.
The first solution is careful trip planning. For me, the time I spend preparing for an overland adventure is almost as much fun as the trip itself. That doesn’t go for everyone, however, so there are a handful of principles that I use to lay out my vehicle’s projected consumption of fuel, and my party’s use of water.
For adventure travel in North America, water is the easier problem to tackle, given certain environmental conditions. The rule of thumb for me is one gallon of water per person per day in wilderness conditions where there is no easy access for refilling your supply. This rate of consumption will increase in hotter climates, and depending on how much water-intensive cooking you plan on, not to mention bathing and cleaning up around camp. On this continent, water is usually never further than a day away, whether from domestic sources or wild. Giving some attention to your route planning ahead of your departure will tell you where and when you will find them.
If you plan to refill your supply in the field, water filtration is a must. Nearly all water sources on American wild lands have some level of contamination from waterborne bacteria, parasites, and other microscopic nasties, including giardiasis, cryptosporidium, amebiasis, and other free floating amoebae. None of these you want swimming around in your gut. In the past, filtering water for a crowd was a hassle, but MSR’s Dromedary water bags and its Autoflow XL gravity filter solve that problem.
Simply fill the AutoFlow's supply bag from your water source, hang it from your vehicle’s roof rack or a nearby tree, and let the AutoFlow sort out the good from the bad while filling a Dromedary bag for perfectly pure drinking water. Be sure to label the “dirty” and “clean” bags, so they don’t get mixed up. Unfiltered water can be used for washing, but resist the temptation to dip your toothbrush in that creek that seems so clear and pristine. Bad idea.
The good news is your water demand is likely going to be much less intense than the thirst for fuel that your rig has. Long distance adventure travel requires that we load our vehicles heavily with all the supplies that make our journeys into remote and wild places both possible and comfortable. This includes the fuel itself that powers our escape pods. The weight is not the only issue, the distance between fuel sources is much more of a dilemma than for water.
Depending on your powertrain, your fuel mileage will vary considerably in different conditions. Consider another truck that I owned - a Mitsubishi Pajero (Montero, in the American market) with a 3.5L V6 engine and an automatic transmission with a low-range transfer case. As a daily driver around town it would routinely return 18-19 miles per gallon. In deep sand, and in low range, and especially when temperatures were high, the mileage would dip down routinely into the single digits. Nine or even eight mpg were not unusual figures. The Mitsubishi’s relatively small fuel tank - 18 gallons - meant that on really long adventures far from gas stations, we needed a lot of extra fuel. A lot.
Altitude, terrain, and temperature all impact fuel consumption, so it’s worthwhile experimenting with your vehicle on short trips in different conditions to see how those variables affect your range. Every vehicle is different, and they all have their strengths and weaknesses when it comes to mileage efficiency. This data will add predictability to the careful calculations that help soothe your anxiety about fuel range on longer adventures.
The second strategy for addressing limited fuel and water capacity is adding extra storage. We’ve examined the weight issue at length here, but in many cases, increasing your carrying capacity is a necessary step. Especially in modern vehicles, modifying or replacing your factory fuel tank is a daunting proposition, both in terms of cost and the actual ability to successfully complete the conversion.
Thankfully, trustworthy brands available from Overlander, like ARB, Rotopax, and Wavian offer a range of safe, lightweight, and modular fuel and water storage solutions. Adding extra fuel safely means installing fixed mounting points - whether on a bumper or a roof rack - for obvious reasons, fuel should be carried if at all possible on the outside of your vehicle.
Water storage is equally worth planning out thoughtfully. As low and as close to the center of your vehicle as possible is the best place to locate your fresh water supply. It should also be easily accessible and leak-free. Rotopax offers some clever and lightweight water storage solutions that are designed specifically for your overland build.
With all these storage options at our disposal, maybe we really are getting back to the future. Have you ever run dry out on the trail? What’s your fuel or water use strategy? Share with your fellow travelers in the comments!
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