FEATURE ARTICLES

THE ESSENTIAL ELAC

Back forty and plus years ago, finding a good peice of bottom was a real task. Once out of the useful distance for shore-ranges, wreck hunters had to depend on their dead reckoning abilities, and later on, the rough accuracy of Loran A. It was impossible to get the repeatable accuracy of fifty or so feet, like we do w/ Loran C, let alone the few feet we get from GPS plotters of today. Some real help was required to find wrecks for the first time, and even find them the fiftieth time.

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Diagram
Enter the sonar scanner. These instruments were powerful "fish finders," whose transducers were mounted on a hoisting tube that lowered it below the level of the keel. Additionally, the transducer was mounted on a yoke-and-pivot mechanism, that allowed the operator to train the beam in any direction, from 130 degrees left to right, and from the traditional vertical, all the way up to horizontal. This system allowed the operator to direct the beam around his position, looking for the bottom. Depending upon the power of the machine, and the nature of the wreck, there was a lot more room for error in the game.

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Head
For those of us who worked on these boats, even after they were disused, the above unit is a familiar sight, the sheer size of which dominated the wheelhouse. This make and model, in particular, was very common. Simrad also ahd a hand in some wheelhouses. But these twenty-by-twenty seven inch ELAC behemoths were the standard. Coupled with the transducer at the end of a hoist tube, they let a captain cover a broad area around him, not just under his boat. For those of us who saw them in service, the following pic is a more familiar sight, as the operator often kept the case open during use, for fine-tuning.

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Head, Case Open

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Speaker Box
Now we add the component that makes the device stand out. The scanner cerrtainly let you find a wreck from quite a distance, and you could watch the wreck "climb" up the paper as you got closer to it. However, at the longer ranges of detection, low-profile structure was harder to see on the paper machine. Yes, a real operator would discern the shadows and tails, but the little box above, tuned properly, allowed him to simply pan the 'ducer around, and by actually listening to the returning echoes coming through the speaker, he could hear the bottom charcteristic change. On some drops, the paper advance would be turned off, and you went only by the sound.

This is a precursor post. In a later thread, or maybe as an addition to this one, I would like to get into the current, and recent, status of the particular unit pictured, and consider it's future. So, depending on how much interaction this thread generates, we will either move on from here, or we can leave this one as a general discussion and historical documentation of the various scanners, and their many famous users, or if it is quiet, I will move on to my biography of this particular unit.

One point I was going to make in the thread about my scanner was about the missing paint on the case. This is mostly due to the duct tape that was placed across it, and nearly every other surface in the wheelhouse. On the tape was written in pen, in big letters, "RAISE SCANNER." I heard stories of some guys leaving them down when crossing the bar, and sometimes dragging them across the bottom in the bay. I was on the boat once, and when we were coming into the state channel, and the most unatural sound came from the boat. Never heard anything like it before, but I knew exactly what it was. Needless to say, it was a event that epitomized the legend of Charie Kennedy. There was screaming and cursing. Never remember one being bent, though.

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Hoisting Tube
But I must say, after trying to pick this one out of my boat (It had to come into the hull, because it was too long to go down, and we hit cement before we got a deep enough hole to go down), how heavy it was. We needed a chainfall to raise it up, between being so slick, and heavy. Anyway, this thing is just about as heavy a thing that I would want to pick up by myself, and that is w/o the oil that it is supposed to be filled w/. A lot of stainless steel in the wall of that tube. But after dragging that thing on the bottom, I would imagine that the plastic ball encasing the ducer would be ripped off.

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Transducer
But it is a testament as to the heavy construction of the unit, that the actual transducer wasn't ripped off the training/tilting mechanism.

If the installation was the same as the way the Gillikens did it, there is no wonder that it didn't effect the hull structure, as one might think. Check this out:

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Sea Chest

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Guide Tube
That little hole is fifteen inches across. I never thought much about having the sea chest in the boat, aside from knowing it was a liability to be remembered. But seeing that amount of dirt through the hole was sobering.

The above tube (Which is upside-down for coating purposes)is bolted to the top of the sea chest, and there is a similar steel pate on the bottom of the hull, w/ fifteen or so stainless bolts running through all around.

I don't think any in-hull scanner unit was designed to specifically find wrecks. These Elacs, and their breed, however, do lend themselves exceptionally well to the chore. And, reading through the six manuals that I have(I have no idea how the last Joseph boat ended up w/ that many Elac books, including one that belonged to Al Rohlman. I also have the Simrad book from the Ben Litwin), I see that Elac did realize the use of their machines in bottom hunting, as it is addressed throughout several of them, especially the LAG models(tilting/training transducers). Whether they saw the market and embraced it w/ technology and modifications, or simply put some print in the manuals to sell units, they did good.

The one thing that sets them apart, and I will repeat myself on this, is the opportunity they afford the operator of getting the ultimate interpretation of the process, and that is by letting him hear the actual return, not just translate it into electrical energy, then scratch it out or display it on a video. No matter how sophisticated a machine is, something is lost at each conversion.

Also, as opposed to all of the "automatic" settings on the machines of today, look back at the second picture of the ELAC, w/ the whole control suite available. I'll put it here for ease of reference:

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Open Case


Now let's narrow them down to a few at a time:Here's a good place to start.

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Lower Panel
The dial on the right is the power switch. However, it's not just "ON" and "Brightness," like today's machines. This dial is a potentiometer. Not only do you turn it on, but you adjust the voltage, by observing the dial on the left side of the panel. When the needle settles into the black area towrds the right end of the dial, you have proper voltage. A critical function, especially when you consider the behavior of the older alternators and generators. of course today's machines have voltage regulators, but they can't compensate for lower voltage.

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Right Control Panel
Here, the left dial is the range scale. Not very sophisticated by today's standards, at all. But it serves the purpose of the machine. There are four ranges. On A1, they are from zero to the depth of scale, forty, 80, 160, and 320 fathom. On A2, they are shifted, so they are 30 to 70, 60 to 140, 120 to 280, and 240 to 560 fathom. On the extended ranges, there is only one ping per belt rotation. You get to aurally savor each signal. The dial to the left of the range scale is the paper advance speed. One is slow, two is fast. Zero, the stylus and paper don't move.

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Left Control Panel
The "1 to 10" dial to the right of the voltmeter is what we would call the gain. They called it echo ampification. The switch below and between the two is turned to the left to select a short pulse length, for shallow water use.

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Time Sensitivity
These dials, in the top left corner, are the time-varied gain feature. After adjusting the regular gain, these two knobs are adjusted in balance. They are actually potentiometers, which vary the power of the amplification. Each one effects a different half of the range. I beleive the Av is the shallow half. Anyway, the two knobs are tuned so that the same objects, at different depths(distances) read the same intensity.

Bill,
"Scanner Wars" were popular on the coast back in the day. Some guys took a while to realize they were getting pounded. And yes, the herring ran many a "sharpie" out of buoys in short time.

I forgot the last part of the system, the speaker box.

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Speaker
The dial on the right is the volume, and the dial on the left is a type of tone adjustment.

And the summary is, after you get done tuning the main unit for a good picture on the paper, then you turn the paper off, and mess w/ the gain, power, and tone dials to get the return echo the way you need it. Well, actually, you usually don't even bother w/ the paper part.

By the way, if you expand the picture above, of the full machine w/ the case open, and scroll down to the very bottom, right hand corner, you will see a switch, w/ the image of a fish to the right of it. This is a "fish filter," which is turned on to display a type of bottom discrimination mode. W/ the switch on, the bottom is no longer thick black, but becomes a type of uniform bar code, and the weaker signals of fish on the bottom, and the second echo, remain solid. The second echo, there's another post coming. Anyone?

By the way, Steve, the stylus marks the paper by burning it electrically. By dampening the paper, the electricity is conducted better, and then the paper burns more. Maybe he had thicker paper, meant for a more powerful machine, or he had a power or stylus problem. I know we paid attention to the striker plate for the transmitting stylus to the right of the paper, to make sure we had good transmission. Another fond memory- As if using the machine wasn't enough of a challenge, try going to work after telling the boss we were low and paper, only to find that he turned the old roll over.

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