By Ross Mabey
There are basically two types of mud, vertically weak and horizontally weak. “Walk softly and carry a big stick”. Before you attempt to cross a mud field that you don’t know, it is best to stop your vehicle, find a long, strong stick or limb and walk across it prodding as you go. This way you’ll know which type of mud you’re dealing with and how to deal with it.
Vertically weak mud is basically bottomless goo, mud with no readily available firm bottom and the most treacherous. Flotation and momentum are the keys to getting through this type of mud. Flotation tires (wide open lug tires) are best here in conjunction with momentum the aim being to keep the vehicle on top. Lowering your tire pressures can help by giving you a larger “foot print” on the ground. While trying to cross deep mud, if you get bogged down and stop, do not keep spinning your wheels for you will only dig yourself in deeper complicating recovery. Put the vehicle in reverse and ease into the throttle to see if you can back out the way you came in, but if you don’t move pretty quickly, again stop digging and get help. In vertically challenged mud, it is best to avoid following someone else’s ruts, better to make your own if possible.
Horizontally weak mud is when there is a thin (or relatively thin) layer of goo on top of a firm bottom. In this case it is better to follow existing ruts, assuming of course that your differentials will clear ground, for they have already cleared the way to the firm ground for you. Normal tire pressures and even narrower tires with an aggressive lug tread can be helpful because you want to cut through the top slick layer to get to the hard bottom. This is one situation where it may be necessary and appropriate to apply some aggressive wheel spin just to dig to terra firma and gain the traction you need.
When crossing what appears to be a dry river or lake bed, again you should get out and walk prodding as you go, jumping up and down can give you a good idea as to how thick the crust is and how liquid it is underneath. Many times the ground will appear to be dry and hard, but under the thin dry crust may be a swamp of bottomless goo. Again, don’t follow existing ruts, use lower tire pressures, maintain steady momentum being careful to avoid sudden throttle and brakes stabs and quick maneuvers that may break the hard crust. Once again, if you do break through the crust and stick, avoid excessive wheel spin so you won’t dig yourself in deeper.
The same rules apply when fording water, you had better get out and check the depth and the bottom before you dive in. When fording, use moderately slow speed. The aim is to set up a small bow wave in front of the vehicle that will help keep water out of the engine compartment.