Now and then it’s good to be reminded of the laws of physics.

A few weeks back I conducted a training weekend for a lovely couple who had recently purchased a very well-optioned Sportsmobile. They wanted to become familiar with its capabilities (and theirs), to learn recovery techniques, and especially to learn the use of their winch, an accessory new to them both.

We spent the first day, Friday, driving and marshaling, and I think hugely improved the confidence of both of them, in addition to opening their eyes as to just how capable a Sportsmobile can be despite its size.

Saturday was winching day. I’d picked a dead-end bit of trail where we wouldn’t be in anyone’s way who happened to pass. It was a hill steep enough to actually work the winch, but not so steep as to be intimidating. The Sportsmobile was equipped with a Warn 12,000-pound winch and synthetic line. For an 11,000-pound vehicle that’s marginal if one applies the standard one and one-half times GVW formula for speccing a winch’s capacity, but we discussed ways to ameliorate this by running out more line and, especially, rigging a double-line pull whenever possible.

The only trees available were both marginal in size and behind a barbed-wire fence, so I set up my FJ40 as an anchor, facing down the hill at the top of the slope.

It was then I realized I’d forgotten my set of Safe Jack chocks, the substantial ones I normally use for winching. All I had with me were the smaller folding chocks I keep in the vehicle for tire-changing duty and the like. No problem, I figured—I set the folding chocks in front of the front tires of the Land Cruiser, and we lugged a couple substantial rocks to put in front of the rear tires. I was in low range, reverse selected, engine off and parking brake pulled out stoutly.

The first, single-line pull proceeded without drama. The winch did not seem to be working over hard (although I remarked that it was one of the loudest winches I’d ever heard). So we re-rigged for a double-line pull, running the Sportsmobile’s line through a 7P recovery ring linked to one of the 40’s front recovery hooks, and back to the Aluminess bumper of the van. I stood to one side and directed while Emmett sat in the Sportsmobile’s driver’s seat and operated the winch remote. He began to spool in and the van crept slowly up the hill.

For about five feet. Then a front tire happened to hit a bit of a rock ledge I’d failed to notice, perhaps eight inches high. The Sportsmobile came to a halt—but the winch, of course, didn’t.

Even as I was raising my fist to give the “stop!” signal, I turned to see my 40 pulled gently but inexorably over the folding chocks, which collapsed as if they’d been soda cans. Behind them the rocks in front of the rear tires had held, but were themselves being dragged with the vehicle.

The winch stopped, and I signalled Emmett to apply the brake and shift to park, then let out some slack in the winch line.

The Land Cruiser had only moved about eight inches. Had we for some reason continued to power the winch, it would simply have kept on being dragged slowly across the ground; there was no chance of it careening out of control. Nevertheless, it was a good lesson in the force an 11,000-pound vehicle and a roughly 24,000-pound-equivalent double-lined winch can put on a 4,000-pound vehicle, even on a moderate incline. The math is pretty simple.

What could I have done differently? Having the larger and sturdier chocks would have made a difference, as might using big rocks instead of the little chocks. Even putting the rocks we used in front of the front tires, and the small chocks under the rear tires, might have made a difference, as the front of the Land Cruiser was being pulled slightly downward in addition to forward. However, a more secure option would have been to daisy-chain the 40 by its back bumper to the base of one of the trees on the other side of the fence with the endless sling I had on hand, then pull forward until the sling was tensioned, then chock.

A good lesson that there’s no such thing as “enough” experience, and there’s never a time to stop learning.

For much more on the forces involved in winching, please read this.

Safe Jack’s heavy-duty folding chocks are available here.