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Wothahellizat Mk2

 

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Wothahellizat Mk2 compared in size to Wothahellizat Mk1.



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Wothahellizat Mk2 construction diaries →


This is a brief description of the design criteria we have for our motorhome. There were three basic requirements, these being,

  1. To be comfortable to live in for long periods of time (years).
  2. Be able to boldly go where few motorhomes have gone before. Which is to say that it must be capable of getting off-road.
  3. To be self sufficient and able to stay in wilderness areas for extended periods, days, weeks or even months.

Let's expand on these a little.

Comfortable
If you're going to permanently live in and run a business from a vehicle, then it has to be fairly large to be comfortable. Wothahellizat Mk1 was 34' (10.5M) in length, this was extremely comfortable to live in but limiting when we got into the bush.

Therefore Wothahellizat 2 is smaller, approx 8.1 metres (26') in length.

Off-road
Many of Australia's best landscapes are in areas that are hard to get to. There are two issues here,

  • The roads are often extremely rough with washouts, creeks, boulders etc.
  • Even if not that rough they are unsealed and usually badly corrugated.

Any motorhome that is to survive these roads for long must be very tough. The normal off-the-shelf motorhome is built more along the lines of a caravan and designed for use on bitumen. Their frames are often made of timber and the cabinet work is usually just stapled together. A vehicle made with these construction techniques will self destruct under prolonged outback travel.

When it comes to getting off road the normal motorhome doesn't cut it either. With long overhangs, high gearing and low clearance they will bottom out on the simplest of obstacles. There are three things that give a vehicle off-road capability,

  • clearance - the higher the better.
  • traction - all wheels must be driven to spread the engine's torque and reduce the possibility of wheel spin.
  • gearing - when the going gets tough you must be able to reduce the vehicle's speed to a crawl but also maintain engine revs. This requires extremely high gearing.

You only get these features in a vehicle designed for off-road use. Combine this with the stronger construction of an off-road vehicle and I believe they are the best choice for the job.

Self sufficient
If you are going to spend time and effort getting to a remote spot it doesn't make sense to stay for only a day or two. If it's a nice place then you want to spend some time there, a few days or even a couple of weeks.

Do this in several places in a row and before you know it you've been a month or two in the bush with no supplies of electricity, food, water etc. Therefore the vehicle must be fully self sufficient for periods of at least a month. This means carrying enough supplies of all kinds. Let's do a few sums.

Beer - I like a long neck (750ml bottle) of home brew each evening. As I make 30 bottles per batch I need provision for at least two batches, one fermenting and one for drinking.

Water - For outback travel you should allow 5 litres per day per person (we'll forget about the beer for the moment). Add 5 litres for washing etc and we have 10 litres per day, x 30 gives us 300 litres for a month. We've managed to fit nearly 600 litres in seven tanks. What about showers? When the water is scarce we make do with a bird bath.

Power - Some people can live with a just light bulb. However I run a photographic business, this means regular use of phones, computers, printers etc. Gas fridges are not known for their reliability and have to be kept fairly level so we have a compressor style fridge. In fact we have three fridges although not all are in use all of the time.

Also, as mentioned several times, I want to be comfortable so I want to run electric fans (in the tropics we sometimes need fans for most of the day and into the night) and not be miserly with the lighting.

Fortunately much of Australia is blessed with sunshine, and plenty of it. Solar is a viable option for lower usage rates but cannot handle high usage. A generator is noisy and requires quite a lot of fuel. Batteries last a lot longer if they are kept "topped up" at near full charge, a generator is very efficient at dumping current into near empty batteries but not so good at applying small top up charges. Solar is exactly the reverse.

What's the answer? In general we are totally self-sefficient with our solar panels and have been living off them since 2001, however we also have a 2kva generator for those times when the sun isn't shining. For example we once spent a month under cover working on the truck, during this time we ran the generator constantly.

Tools - If you break down in the outback you don't just call the AA, you fix it yourself. This means a comprehensive set of tools including welding equipment.

This all adds up to a lot of space/weight. Most motorhomes I've seen don't even have enough storage for the 65 bottles of beer, let alone the food, water and myriad of things I haven't mentioned. You need a large truck to be able to carry this amount of supplies.

Design criteria

Our ACCO has a GVM (Gross Vehicle Mass) of just over 14 tonnes which is more than enough to carry all the above.


Right elevation, truck in driving mode.


Left elevation, truck in camping mode with
motorbike dropped down and deck folded out.

Kitchen
On the left we have the kitchen bench with a sink at the bottom and three-burner cook top at the top. The mangle stores in the utilities area and swings out over the sink.

On the right are various storage compartments, pantry, fridges, beer etc. There is also a nook with a small shutter, this gives a little more bench space and will be used for coffee making. The shutter will provide some airflow to what is otherwise a fairly dead air area.

Shutters
All "windows" are really openings with shutters and no glass. As with Wothahellizat 1 we are going for maximum ventilation and this version will have even more.

Bathroom & entrance
The 800-odd millimetre square area that on most motorhomes is just an entrance has several uses. Depending on what is slid out or opened up it is a shower, toilet, vanity, or kitchen bench, and of course an entrance.

Utilities
All the gas and water systems are contained in this area, there is no piping of any kind leading off into walls to get to other parts of the truck. This makes things cheaper and simpler to build and a lot easier to maintain. There will be a large shutter on the outside that, when open, will allow easy access to everything.

Originally I wanted the electronics to be here as well but that didn't work out so the batteries, inverter, gauges etc will now be in a compartment behind the left side of the lounge room.

Deck & motorbike
When driving the motorbike stores in an area that is either the front of the lounge room or the rear of the deck according to what's open. The bike is in a compartment that lowers to the ground with the roof of the compartment becoming the floor of the rear half of the deck.

The rear wall of the body opens both up and down to become the second halves of both the deck roof and floor. If the rear wall is not opened then we have a larger lounge room.

When the panels are open the rear half of the deck is protected from the elements because it is actually inside the body, although it to has shutters that can be opened if more ventilation is required.

Lounge room
The lounge room has a full height passage down the centre but the chairs sit on plinths about 300mm (1 foot) high. Inside these plinths are six 84ltr (19gal) water tanks giving a total 504 litres (112gals) stored internally with another 84 litres in an outside tank.

The rear wall of the room are glass bi fold doors, when open these provide 100% opening to the deck area, or if the deck is closed, opening these doors creates a larger room.

Bedroom
The bedroom sits over the cab and encroaches slightly into the kitchen area. It to has shutters all around for ventilation. There is only about 650mm (25") of headroom but there is a huge hatch that opens the roof to the sky.

Specifications

Whereas the "Design Criteria" section describes the basic rational behind the major design decisions, this section covers the actual specifications of the motorhome.
Chassis   :: International ACCO Mk 5 ex-Army vehicle. The chassis has been extended by 1 metre.
Engine   :: Perkins 6354 diesel. 6 cyl, 6 litres (354ci), turbo charged.
Gearbox   :: Eaton SMA 475, 5 speed synchromesh.
Drive train   :: Hi/lo range transfer case. Six wheel drive. Permanent four wheel drive on rear bogie and selectable drive to front wheels.
Wheels   :: Split rims with 1200/20 tyres, 1 spare wheel/tyre, 1 spare tyre.
Brakes   :: Standard air over hydraulic split system enhanced with Jacobs exhaust brake.
Electrical   :: 12v truck, 24v & 12v house. Total re-wire of truck harness performed.
Dimensions   :: Width 2.35m (7'8"), height 3.4m (11'), length 8.1m (26').
Weight   ::
  • Chassis (raw, no tanks etc): 6 tonnes (13,200lbs)
  • Chassis (including tanks, spare wheels, storage bins etc): 6.5 tonnes (14,300lbs)
  • Total: 12,500 kgs (27,500lbs)
  • GVM: 14,020 kgs (30,844lbs)
Ground clearance   :: 350mm (14") under diffs, 500mm (20") under most of chassis.
Angles   :: Entry - 47 degrees
Exit - 47 degrees
Ramp over - 140 degrees.
Fuel   :: 600 litres (130gals) diesel, 100 litres (22gals) petrol (for motor bike & generator).
Range   :: 1800k (1125 miles) on-road. Off-road, depends on terrain.
Recovery   ::

20,000lbs (9 tonnes) PTO driven winch, pulls to front or rear. 2x ground anchors, assorted shovels, chains, straps, snatch blocks etc.

Water   :: 588 litres (130 gals) drinking/fresh in seven tanks, 55 litres (12 gals) grey. Serious filtration on drinking water, use water from anywhere.
LPG   :: 4 x 9kg bottles.
Power   :: 4 x 100w, 2 x 125w and 4 x 250w solar panels giving a total of 1650 watts nominal of panels generating 51 amps @ 24 volts. 3300 watt inverter is also a 100 amp 24v battery charger.
Generator   :: Honda eu20i, 2000-watt 4-stroke inverter style generator. Used only for backing up the solar system.
Batteries   :: 14 x 120Ah 12v deep cycle AGM batteries makes a 40,320Wh battery bank or 1680Ah @ 24v.
Appliances   :: Three burner Highland gas cook top, 240 litre 24v Fisher & Paykel fridge (120 fridge, 120 freezer), 30 litre Endel drawer fridge, 15 litre Engel chest fridge/freezer. Atwood gas hot water system. Spinflo gas oven/grill. Dometic (aka Eiberspächer) diesel heater.
Cladding   :: 2mm aluminium tread plate over all of body. No protrusions or visible windows/doors.
Body   :: The body is made entirely from steel. It is mounted to the chassis at four points (diamond pattern) using special rubber mounts. This system allows the chassis to flex without affecting the body and also provides good vibration isolation.
Storage   ::

Provision for 65 long neck beer bottles and three months food.

Communications   :: UHF and AM CBs, hand-held UHF, NextG mobile phone.
Safety   :: Powder and refillable water fire extinguishers accessible from outside. Powder extinguishers and fire blanket inside.
Other features   :: All heavy items below chassis and most storage as low as possible.

Tropical roof provides shade, also well insulated with ThermaSheild paint and closed-cell foam.

A small compressor for running air tools and pumping tyres but also used as a backup for the engine's compressor.

Massive windows in living room fully open for ventilation.

Bedroom has full-length "windows" (just openings, no glass) on three sides at bed level to provide cross ventilation.

Garaging for one Honda SL230 motor bike in lounge room.

"Slide-a-loo" toilet opens out for use then returns to allow passage through entrance.

Rear deck folds down to provide outdoor living space.

Body can be pressurised while driving to help keep dust from entering.

Fully self contained in the bush with no facilities for periods of at least one month but probably up to three months.



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