Grapple logging is one of the more bizarre methods of logging. This is accomplished with 3 lines. the haulback is used as a running skyline which runs out through the carriage, to the tail hold and back to the carriage so it both supports the carriage and pulls it out.
As with any cable grapple, 2 main lines are used---pull one to open the grapple and the other to close it. For those who haven't seen one, a cable grapple is a simple mechanical device with 2 cables on it. One cable is attached to a linkage such that if the grapple hangs from it, the grapple will hang open, and the other cable is attached to the grapple hangs closed.
In concept, the operator runs the carriage out until the grapple is over a log, then lowers the grapple hanging it by the grapple open line, then takes up the closing line pulling the grapple closed and lifting the log. The operator then reels in his catch.
The donkey puncher only needs to work 3 drums in a coordinated fashion in order to make this happen. Now add to this the fact that the log is 1000 feet away and out of site, and unless you are Superman, you can't see plus or minus a few inches at a 1000 feet away anyhow. Because of this you have a 'spotter' out in the woods who can see with a walkie-talkie talking the operator into grabbing a log.
The good news of this sort of an operation is that it takes a very small crew, just the donkey puncher and the spotter who will also change roads as necessary. Given that absolutely no lateral yarding is possible, this system works best with a tail cat that can be moved frequently.
The bad news is that the method is not particularly productive because you can spend a lot of time fishing, and can only bring in a single piece. It does, however avoid the need for choker setters and chasers whose jobs are among the most hazardous in the industry.
The only operation that this writer is personally familiar with that used this method, actually employed it at night. During the day yarding was done in the conventional manner with chokers, but the company put on a second work turn on swing shift and turned on the lights. A 2 man crew could then get some additional production out of some very expensive machinery. You see, those yarders are usually the single most expensive piece of machinery on the landing, and those payments accrue by the month, not by the hours of operation.