Feature: Treading Water

Lloyd Junor — 8 June 2010

When confronted by a water crossing it is advisable to initially make an assessment of the depth of water and the amount of time it will take to complete the crossing. Sometimes this will mean stop, turn around and go back, or else wait until the water level or distance is less. If you wish to proceed it could involve a little or considerable preparation.

If the van floor will be clear of the water surface, then it’s likely you can manage with minimal preparation. If there is a visible road surface all the way through and the water is tyre deep, it’s likely that no preparation is required. To find out whether water might enter the caravan during the crossing, measure the height of the caravan floor from the ground. Then add another 150mm at least because there may be unknown potholes under the water surface.


But there is a little more to this than meets the eye, because you need to take into account those invisible potholes and the impact they might have on objects beneath the van body. Look at the position of the water tanks underneath: would they strike a rock or other object if a wheel dropped down 150mm? If the risk of this happening is high, then you might decide to avoid or postpone the crossing.

Another factor to take into account is the speed of the stream. Anything submerged will create a pressure wave on the upstream side of the object, and this is an effective rising of the water level on one side of the van. The faster the stream flow, the higher that pressure wave will be. If it happens to be on the side of the van where you have the door or external lockers, then you increase the risk of water entering the van and flooding the interior unless you take steps that will lessen the risk.


Any impervious material will assist in preventing water entry through external openings that all caravans have. So-called ‘90 mile an hour tape’, duct tape, masking tape – these can be used by themselves to cover gaps or they can be used to attach plastic sheet across holes. Naturally, the stronger the tape and its adhesive properties the better. Plastic sheet could be garbage bags, or items such as canvas from camp chair seats or spare wheel covers can be utilised to waterproof external openings. Remember that there will some directional pressure on these as the van moves through the water.

Unless you have a specifically-built offroad caravan there are likely to be gaps in the floor where pipes, plumbing and wires go through. To seal these gaps can be a time consuming and exacting task, and you would need to have maybe more than one tube of a sealant such as silicone or butyl mastic to complete the job. Look inside all cupboards for these through-the-floor gaps. By regulation the battery compartment will have an air vent in it, but this must not be permanently blocked.

A quite important issue to be alert to is what the effect of blocking across vents can have. A refrigerator usually has an air vent low to or through the floor, and this must not be blocked off while the fridge is running on gas. Turn the gas bottle off. The same applies with a gas hot water unit. Water entry into these appliances could very well make them unusable, as they have 240-volt connections which will short-circuit if moisture gets near them.


A word of caution: vans do not behave predicably during water crossings. I have seen poorly prepared vans scoop water and emerge from the crossing in a dreadful condition, bowed down due to a huge weight of water inside, virtually wrecked in moments. Others have been so well prepared (and light) that they have literally floated. When a caravan floats, it will swing around due to the current and possibly smash into the rear of the towing vehicle.

Most caravans are not built to be regularly subjected to water crossings. If the underfloor timber is not sealed, it will eventually deteriorate if frequently wet. It is nearly impossible to prevent water from rising into the wall cavities unless the van has been sealed during manufacture. Wheel boxes might not be well sealed, and thus admit water. So it’s not wise to unnecessarily subject a caravan to immersion. While it may look as though the van has not suffered immediately, six months later the effect of immersion might begin to show up.


After completing a water crossing, all the temporary water seals – the tape, the plastic sheet, etc. – will need to be removed. If the axles and wheel bearings have been actually immersed in the water then there is a distinct possibility that water will have entered the bearings. Almost certainly the water will have been gritty, and so to prevent bearing failure it would be prudent to remove the wheels, bearings and brakes to clean them and re-pack the bearings with fresh clean grease. - Lloyd Junor


Water crossing Lloyd Junor