Monday, March 01, 2010


Sam Smith

The difference between losing your grandmother and losing a technology is that it's much harder to replace your grandmother than it is a technology that, after all, almost inevitably vanishes because something better has come along.

Hence perhaps the silence about the disappearance of Loran as of last month - a navigational system that aided millions to get where they were going and prevented innumerable deaths and accidents.

After reading that the Coast Guard had shut down its Loran stations, I went to the basement to find some remnant of my last small portable Loran. There was nothing. Not even a well-fingered manual. Clearly, GPS had been such a joy that I had not the faintest nostalgia for its predecessor.

Loran also had the misfortune of being on the way out as the Internet was on the way in. Thus even finding online evidence of its existence and utility is not that impressive.

On the other hand, it was important enough to me to at least say good bye.

Like the day I made it home in a summer fog from an outer island in Casco Bay while a number of other vessels, following only each other, ended up on a mudflat.

Or the times while operations officer and navigator of the Coast Guard Cutter Spar, I tried to focus on the Loran screen while the vessel was taking 30 degree corkscrew rolls as we searched for a fishing vessel in trouble. It wasn't a happy experience save for the fact that without that device we wouldn't have known where the hell we were.

Here's how Wikipedia describes the principle:

"The navigational method provided by LORAN is based on the principle of the time difference between the receipt of signals from a pair of radio transmitters. A given constant time difference between the signals from the two stations can be represented by a hyperbolic line of position. If the positions of the two synchronized stations are known, then the position of the receiver can be determined as being somewhere on a particular hyperbolic curve where the time difference between the received signals is constant. . .

"By itself, with only two stations, the 2-dimensional position of the receiver cannot be fixed. A second application of the same principle must be used, based on the time difference of a different pair of stations. . . . By determining the intersection of the two hyperbolic curves identified by this method, a geographic fix can be determined."

By today's standards, it had numerous deficiencies including the inability to tell you where the nearest Starbucks was.

And by today's standards, the whole character of navigation in the 1960s seems almost medieval. The Spar was a buoy tender and for every one of our 170 buoys we knew the correct angles of three fixed shore objects such as a tower or building. On each wing of the bridge a quartermaster would take hold a sextant horizontally and read off the bearings between two of the objects.

A single screw ship, the Spar was not easy to maneuver and we approached the buoy location dead slow, the quartermasters calling out their angles: "76 degrees, 13 minutes on the left -- correcting." From the other wing: "82 degrees, 52 minutes on the right -- uncorrecting." I would stand on a wing of the bridge with a chart and three-arm protractor keeping up with the position of the ship. As the position plotted over the right black or red dot on the chart I would tell the captain, "She's on." He would cry to the chief on the buoy deck below, "Let her go." A seaman swung a mallet to the chain stopper. Fifteen tons of sinker and buoy were released and as she settled into her position, a final check on the angles was made we backed away.

Buoy tenders were unusual vessels in a number of ways, one being that they went places - such as close to rocks or sand bars - that 180 foot vessels weren't meant to approach. But the scariest days for me  were setting buoys in a channel leading to a naval base. Most buoys could be a bit off and no one would notice, but anyone coming up the channel could see if these were aligned. 

I had come aboard the Spar as navigator with only sailing experience and thirteen weeks in OCS behind me. I was to lead men who knew much more than I did.

My first test was on the bridge. The captain suggested I take a navigational fix. For piloting fixes, one sighted three shore based - and charted - objects using the peloruses on either wing of the bridge. These were compasses on a stand with telescopes mounted on top so one could read the bearing and see the object at the same time. Once having read the bearings, you stepped into the pilot house and with a parallel rule transferred the data to the chart. If all went well, your three bearings met in a point or tiny triangle at the exact position of the ship. If all did not go well, such as one of the bearings being off, you were left with a bloated triangle and a far vaguer idea as to where you were.

My first triangle was considerably larger than desired. Beside me was my first class quartermaster, Bill Miller, a QM2 and a seaman assigned to my department. I couldn't really see, but I felt the executive officer and the captain looking over my shoulder as well. I kept my eyes glued on the chart without saying a word, thinking desperately what to do next. The holy spirit put the right words in my mouth. I turned to Miller, shrugged, and said, "Not bad for a fucking reserve, huh?" I could tell from the reaction that I had passed the test -- which was not, after all, to prove how good I was, but to admit that I wasn't.

The sextants and pelorus we used every day because we were in sight of land. The Loran was saved for search and rescue missions and long trips. 

And for the day that the Nantucket lightship went off station. Both its radar and Loran were busted and we were assigned to get it back on station. By this time I had come to think of direction in new ways: declining angles, invisible curves emanating from Loran stations I would never see, and tiny triangles that defined the core of your existence. But to use one's own actual Loran position and relative radar position to another vessel to direct that ship to its desired destination was something no one had told me how to do, yet thanks to my high school math teachers it worked well enough for government work.

I sometimes think of that moment while toying with the nifty GPS in my car and wonder if humans in their politics and culture will ever be able to make as much headway as we have in moving around since the days of sextants and Loran.