Electronic Design

Bob's Mailbox

If any of you readers don't know why it's important to stand far away from taut cable or rope, here are the reasons! /rap

Dear Bob:
Would you believe I just got the latest issue of Electronic Design? The first thing I did was find your column to read. Much to my surprise, it was about knots (Electronic Design, March 5, p. 156). This stirred up a painful memory for me.

It was a Friday morning in February, 1976, on the Columbia River Bar, just outside of Ilwaco, Wash., at the USCG's Motor Lifeboat School. There were about six of us on a 44-ft. MLB practicing towing a disabled boat through the breakers just off of Jetty "A." The boat that we were towing was a 25-ft. surf boat used by the Coast Guard to get close to the beach. Attached to the surf boat were a 1.5-in. (diameter) double-braided Samson (nylon) line, about 20 ft. long, plus a 3-in. double-braided Samson, about 80 ft. long. We used a sheet bend to attach the two lines, using the 3-in. line as the bight.

Myself and one other person were outside of the relative safety of Cox'ns flat, toward the stern. The Cox'n did a good job of powering through a 12- to 15-ft. breaker. I turned back to watch how he would do pulling the surf boat through the same breaker. I saw the bow of the surf boat start through the backside of the breaker about 100 ft. behind us, when the sheet bend let go. The sight of a 3-in. line whipping at you is not fun! The line didn't even touch the water before hitting us.

I caught a bight of that line on the right side of my face. The other guy got hit in the back with a bight of line. You could see the individual threads of the braid in the welt on his back. My nose and right eye immediately swelled up so that I couldn't see from that side, and my left eye was very watery. All 80 ft. of the 3-in. line was draped across the beam of the boat and in the water on both sides. At the board of inquiry, it was decided that two half-hitches should have also been employed. From then on, the USCG's MLB school has taught to use two half-hitches along with the sheet bend. As for my nose, there's a small bump on the right side.
Terry L. Kerr
via e-mail

Wow, Terry, the concept of "seeing the bullet that hit me" is frightening. It must be pretty scary to see the hawser headed right at you, knowing what's coming next. At least it wasn't a steel cable. I guess there's never too much safety when it comes to standing in a safe place, far from the danger of the taut hawser—and adding those half-hitches.—RAP

Dear Bob, My Man:
I thoroughly enjoyed your piece on knots in the March 5 issue. 'Tis nice to step out of the lab once in a while, isn't it? If the length of your beard is any indication, you certainly remember the good old days of waxed lacing cord, used in nigh every piece of precircuit-board electronics equipment—and even some post-pc-board applications. (I have seen people who were required to use it, but I never considered that as the best way to make reliable circuits. I never had to use it myself, and usually my technicians didn't have to either. /rap)

I remember the ARRL Handbooks from that era had an extensive section on wire lacing and the proper way to tie the hitches. If you did them incorrectly, one tug would unwind a week's worth of intensive labor on your latest Heathkit! Well, all of that had become a lost art with the advent of nylon Ty-Raps and other clones—or so I had thought.

For a few years, I worked in a telco central office, wired together with all of the latest and greatest fastening technology. Crawling around the equipment racks all day, I would usually emerge with my arms looking like they had been through a meat grinder. No matter how flush you cut a Ty-Rap, you would always have those sharp edges.

A couple of years ago, we expanded our telco operations and enlisted the help of a Canadian telco firm to assist with the substantial move. Lo and behold, these old geezers wired up the telco office with—you guessed it—waxed lacing wire! The result was nothing short of beautiful, and they were every bit as fast as I was with my newfangled Ty-Rap gun. Best of all, the bundles were smooth! I didn't carve up my forearms fishing wires through bundles. I could emerge from close encounters of the telco kind with nary a scratch! There must have been 900,000 knots tied in that installation, and every one was correct and perfectly evenly spaced. As a result of this, I have ejected my Ty-Rap gun from my workbench and retaught myself the fine art of wire-lacing. From one old knot to another.
Eric Nichols, KL7AJ
via e-mail

Thanks for writing, Eric. I'm not a big Ty-Rap fan either. Best regards.—RAP

Dear Bob:
In your column on knots, you say, "You should never...use a granny knot...as it's likely to jam up or slip." "Jam up" and "slip" are polar opposites. If it jams, it won't slip. So I would think that a granny is a safer knot than a square knot.
David Hadaway
via e-mail

Hello, David. No, the condemnation of the granny is because it may hold, or it may slip, or it may jam. You can't be sure what's going to happen. In other words, if I added three half-hitches to a granny so it couldn't slip, it would probably jam and be very difficult to untie.—RAP

All for now. / Comments invited!
RAP / Robert A. Pease / Engineer
[email protected]—or:

Mail Stop D2597A
National Semiconductor
P.O. Box 58090
Santa Clara, CA 95052-8090

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