I am lucky enough to fly for an international airline that actually pays me to journey throughout the world. On a recent layover in Bangkok, I happened to receive a practical lesson in sailing physicswindage, thrust vectors, and centers of pressureaboard an unlikely vessel.
After a long morning of touring the Grand Palace and viewing the Emerald Buddha, I experienced the amazing sights and awful smells of a nearby open-air market. While I have never been actively airsick or seasick, I very nearly regurgitated my breakfast of mango crepes as I walked through the rows of raw fish, meats, and various spicy sauces which had spent the day curing at 95° F, along with collecting the flies, dust, and dirt of the city. The nearest place to find some fresh air happened to be a major boat landing on the Chao Phraya River, which serves as a major avenue of transportation through Bangkok.
I looked around for someone to tell me when the next very cheap, seven-baht (about 30 cents) water taxi would be coming by, to take me upriver to a planned dinner rendezvous with the rest of my crew. At this dock, which was also home to all kinds of river vessels and watercraft, a tiny, friendly, and very pregnant young lady noticed my foreign pallor and gullibility, and proceeded to convince me that the taxi would not arrive for half an hour and I would much prefer to ride in luxury in my own personal “long-tail” motorboat. Her sales technique overcame my pilot’s frugal nature, and after many minutes of intense negotiation I hired a private launch for the exorbitant rate of seven U.S. greenbacks.
That afternoon, however, an unusually strong wind was blowing straight down the river, contrary to our intended path upriver. The beckoned long-tail pilot made many attempts to land his extremely long, thin vessel at the dock, as he furiously heaved back and forth on the huge engine, which was mounted high on a swivel above the transom. From the rear of its transmission sprouted a long, bare shaft with a propeller that popped in and out of the waterhence the name “long-tail.”
Of course, as the helmsman labored to maneuver his craft to the jetty to pick up his passenger, I noticed the cheap, seven-baht water taxi come and go on the other side of the dock. Nevertheless, I stuck with the original agreement, and I finally stepped aboard what appeared to be a new and expertly varnished mahogany long-tail motor launch. Standing in the stern was also a very new but, as I would quickly discover, not so expertly trained long-tail driver. He turned out to be husband to the pregnant little lady on the dock.
We were stern to the wind, which required an about-face back upwind and upriver. I noticed a definite lack of response to the 1,000-pound helm and saw the skipper finally realize he was piloting a sailboat more than a powercraft. He sprang forward and put a few wraps of line around the canopy that stretched over the 30 or so empty wooden thwart seats. This resulted in a successful tack upwind, and we were finally on our way. I thought that would be the end of our troubles, but I soon deduced that the lack of ballast (two people vs. a design load of 30 or more), plus a long, moderately high freeboard and a furled canopy above our heads, equated to a center of pressure well forward of the center of resistance. Add to this a very hefty thrust vector trailing well behind the transom. With the wind dead ahead, any slight deviation off course presented our beam to the wind, which in turn created a disturbing lack of response from the helm. This became very apparent when I noticed us drifting to the left side of the river, directly into heavy traffic, and straight toward a concrete piling set near the edge of the riverbank. I would not have panicked were it not for the labored gyrations of our helmsmen and the equally panicked look on his face. The big six-banger he was desperately trying to swing to and fro simply would not overcome the force of that storm jib set above our heads, furled as it was. But at the very last minute, and much to my horror, just as we were about to carom off the side of the obstacle, it was “damn the torpedoes, full steam ahead,” and a sudden opening of the throttle gave enough of a spurt of power to kick the tail around just enough to put us about on a port tackback toward open water and the correct side of the busy channel.
After my heart rate dropped a bit and the adrenaline drained from my system, my thoughts somehow turned to my own Islander sloop. I realized that she, too, responded to her helm similarly when backing up or while making very little headway. Her bow would always take off with the wind, and no burst of the throttle or turn of the wheel would stop it. Maybe if I mounted her Perkins diesel up on top of the transom. . . .
Gregory L. Pfeiffer is a retired Air Force officer who flies 747s for Northwest Airlines and lives in San Diego.