OK, so you have prepared your vehicle and you are now at the edge of a river which you want to cross.  What next?

Well the first thing to do is to stop and think.  If you take a little time over this, good! It will allow your transmission and diffs a chance to cool thus reducing the risk of water being sucked into your diff past the seals when the hot diff is cooled suddenly by the cold water. Those seals are designed to keep oil in, not water out.  And don’t forget to turn off your headlights, if you had them on, to give them a chance to cool too. (You weren’t really intending to cross in the dark were you?)

You should be asking yourself,

• Should I be crossing at all? and   
  
• Should I be crossing here?

If the river is discoloured, swollen, fast flowing as evidenced by pressure waves and white water; if you can hear rocks rolling along the bottom; or if logs and other debris are being carried along, the answer is plainly no!. If it is raining either where you are, or in the headwaters, and the river is rising or likely to rise and you don’t want to be caught out on the other side, the answer is also probably no. How do you know if the river is rising? Build a  small cairn or plant a stick at the edge of the water.

Rivers in New Zealand can rise very rapidly at times.  I can recall one river in the Wairarapa - the Ruamahanga I think it was.  I was parked close to the edge of the water where I was cleaning a fish I had caught the night before.  I observed one or two small branches being carried along by the current and then noticed the water visibly creeping over the stones towards me.  I hastily retreated to my truck and made for the exit about a 100 metres away.  By the time I reached it the water was up to the hubs.  Half an hour later the river was bank to bank with logs and branches being carried downstream.  It wasn’t even raining where I was!

Crossings at night or in the dark are not advisable unless you are very familiar with the crossing.  I do admit to crossing the Wairau River at midnight once to get back to my campsite up the Goulter. But I had crossed earlier in the evening and carefully marked the entry and exit points with stone cairns in anticipation of the return crossing. Even so I had a little difficulty finding my way across the river flats after I had forded the main stream.

If you decide you do want to cross, then take time to consider where the best place is. Don’t automatically assume that the place you crossed last time is still safe, or that the wheel marks “exiting” on the far side indicate that it is OK. They might be entering, not exiting, and may never have made it to your side!  Rivers can change dramatically after floods.

If you are an experienced tramper or hunter you will have developed an eye for suitable crossing points.  You are looking for a wide shallow crossing with a firm bottom free of large boulders and other obstructions.  Such fords are frequently found at the end of a pool just above the next set of rapids as shown in the picture (right).  On a large braided river you can often break the crossing into a series of smaller crossings between islands.

The ideal bottom is composed of small stones.  Be wary of sand and pea gravel though, which can be treacherous. Pea gravel can act like so many marbles under your wheels and can play havoc with disc brakes if a stone becomes wedged between disc and pads, especially if you have a diff lock.  If you become stuck in sand the current can undermine the wheels to such an extent that it overturns the vehicle, as I witnessed once when contemplating crossing a flooded wadi in the Yemen.  (Useful lesson - let some other idiot, preferably a local, try first!)  Be careful also of river debris such as logs or trees which may have been undercut by the current so that they are surrounded by a hole.  Surprisingly quite large boulders and rocks can be traversed especially in deeper water where you tend to “bounce” over them, but don’t rely on this technique, you are just as likely to get hooked up.  Rivers are usually deeper on the outside of bends so try to cross on a straight.

Planning a crossing preparatory to some crowbar work. Note the snatch strap used as a safety rope in case 1 slip. This crossing was complicated by the presense of an abandoned Hilux in the middle of the ford. (see part 1)

Plan your path carefully - where will you enter, how will you avoid that rock, where will you exit?  Are there any suitable anchors on the other side for winching yourself out if you get stuck? (Get into the habit of casting your eye ahead of obstacles to identify potential anchors). Have you got enough rope to reach them?  Where will you end up if you are carried downstream?  Stand on a boulder, your truck roof or other high point and look at the crossing through Polaroid sunglasses to spot boulders and other obstructions.  In fast-flowing water submerged rocks can be detected by the “pressure wave” above them. Remember that the water is about a third deeper than it appears due to refraction. The ideal path is one angled downstream slightly so that you get some current assistance and don’t build up a huge bow wave.

If in any doubt walk it first with a stout stick, if necessary, for support. (A useful tramping tip in a strong current is to place the stick on your upstream side where it is pushed into the bottom rather than away from you.) Walk side-on to the current taking short steps feeling each foothold as you go. If in doubt don’t try it or have someone belay you with a rope.  If you can walk it you can drive it.  When by yourself a safe rule is - if you can’t walk it don’t drive it.  Even when in the company of other vehicles think twice about crossing if you can’t walk it, even if experienced. And don’t be pressured into “giving it a go”.  Be particularly careful if driving a light vehicle such as a Suzuki. (Could one of you Suzuki or Daihatsu owners please give some tips on crossing with these vehicles? - Yeah, I know you just fit a propellor or get out the oars!) 

If you haven’t taken special precautions to prepare your vehicle for water crossings (See Part 1) be guided by your manufacturer’s recommended maximum fording depth.  On Nissans and Toyotas this is generally 600mm or 2 ft. That is roughly half way between the hub and the top of the wheel. (Not the steering wheel!)

Side creeks and streams are often as tricky or trickier than the main river.  They usually have fewer if any crossing options and they are frequently fast and bouldery.  The crossing can often be improved by a little “road building”. Quite large boulders can be rolled downstream with the help of a crowbar, and a few carefully placed rocks can often lift a wheel sufficiently to avoid scraping a diff or suffering sill damage. Remember that rocks are a third lighter when submerged than when out of the water so watch your back when lifting or moving them, and don’t stand downstream of a boulder you are trying to shift in a strong current!

During a dry spell creeks and rivers often experience strong algae growth - a brown slime on the bottom which can be very slippery. I have even had to winch myself out of a shallow river because of the slime even though the water was barely over my ankles!

And before you cross any river check that there is not a fisherman downstream of you. They do not take kindly to their water being disturbed!  Upstream is not so critical - I have spotted fish upstream in the middle of a crossing seemingly unperturbed by my wash - but it would still be wise to talk to any upstream angler before crossing!  He might even know a better ford.

In a subsequent issue I will cover Part 3 - The Crossing itself. If anyone has any comments or suggestions on any aspect of this series send them in please.  It is easy to overlook the obvious or omit the crucial!