This year, a helicopter developed by a team of young NASA engineers flew on Mars and became the first vehicle to fly successfully in the atmosphere of another planet. The technicians famously proclaimed the initial hop to be their “Wright Brothers moment,” and compared the Martian flight to the first sustained powered aircraft flight by Wilbur and Orville Wright in 1903. The eureka feeling of satisfaction stemming from such an accomplishment is difficult to describe to anyone who has never dreamed, planned, and surmounted obstacles to reach such a goal. I know that feeling.
In 1972, just after graduating from high school in Highland Park, Illinois, along with my friends Louis and Marty, I spent most summer Sundays racing 15′ Albacore-class sailboats at our local sailing club on Lake Michigan. One day, Louis and I stumbled upon the book The Forty-Knot Sailboat, by Bernard Smith, buried in the stacks of the Highland Park Public Library. The book, published in 1963, discussed the theory of hydrofoil sailboats, including their history and predictions for the future. While only a handful of experimental hydrofoil sailboats had ever been built by 1970, Marty, Louis, and I were inspired by Smith’s book and decided to design and build our own prototype hydrofoil sailboat. Our initial hope was to develop a class of hydrofoil sailboats that could become popular for racing and high-speed day-sailing.
Our budget was a mere $100. We were neither engineers nor boatbuilders, and high-tech lightweight materials such as carbon fiber had not yet entered the consumer market. Although these initial obstacles should have thwarted our plan, youth, idealism, and persistence kept us on track. We immediately set to work.
Marty, who later became a successful industrial designer, was a talented artist and sketched a few concepts that more closely resembled futuristic spaceships than any known watercraft. It was a start. Louis and I studied Smith’s book and joined, by mail, the Amateur Yacht Research Society in England to obtain its scientific publications pertaining to hydrofoil theory and design.
We decided upon a monohull with three lifting foils in a “canard” configuration. Rather than have the rudder and its foil in the stern, the most common arrangement today, our rudder and foil would be attached at the bow and the two main lifting foils would be located on either side of the hull, just aft of the center of gravity.
We were determined to learn foil theory and, for a while, even attempted to perform our own original research in hydrofoil shapes and wingsail designs. First, we constructed a test tank in the basement of my house by building a 7′-long wooden trough equipped with a plastic liner. We attached homemade plasticine hydrofoil models to one end of a rudimentary balance arm, which would pivot in a vertical plane around a horizontal axis mounted on the top of a classic Lionel model railroad car, which ran along a railroad track on the side of the tank. A long rubber band provided a repeatable force to pull the assembly through the water. The outside end of the balance arm was outfitted with a pen to mark its path on an 8′-long sheet of paper mounted horizontally on a board next to the tank. Each foil section we tested created its own unique tracing, giving us an indication of the foil’s lifting ability. We fiddled with Reynolds numbers (ratios of inertial and viscous forces) in the hope of scaling our data to full size. Needless to say, we never reached any meaningful conclusions from our crude experiments, but we had a great time trying.
Next, we decided to find a place to test some of our wingsail ideas. On a whim, the three of us drove to Northwestern University in nearby Evanston. It was early July, and the campus was a ghost town. We found our way to the deserted engineering building and boldly walked in through the unlocked front door to find a professor who might help us. The professors’ names were all painted neatly upon the frosted glass windows of the dark-stained wooden doors throughout the timeworn, traditional-style university building. Only one light was on. We knocked on the door. A gray-haired gentleman was surprised to have visitors, but instantly warmed when he learned that we were high school students with an interest in hydrodynamics and airfoil design.
He walked us through the empty building and into a dusty, cavernous room that housed a wind tunnel, dormant since the 1940s or ‘50s. Fortunately for us, he happened to be the professor in charge of this wind-tunnel lab. He demonstrated the circuit breakers that turned on the fan motors and showed us how to mount test models, equipped with strain gauges, inside the tunnels. Upon our request, and much to our surprise, he provided us with keys to the lab and granted us permission to come and go whenever we wished: day or night. Security in those days was based entirely on trust. Three enthusiastic high school boys probably represented a refreshing antidote to his dull, quiet summer. The whirring motors of an archaic wind tunnel in an abandoned lab filled with long-forgotten physics projects represented the greatest toy a teenager could imagine. Just having the key to a university building made us feel important.
We “played” with the wind tunnel a few times testing our 1:25-scale wingsail models, always wondering if some guard or faculty member would catch us conducting experiments as impostors. We were never discovered, but we also never managed to generate any useful data. Nonetheless, it was great fun to power-up the wind tunnel and watch our models flutter around through the small observation window.
As the summer progressed, we finished drafting plans and set to work constructing the hull. My parents graciously allowed us to commandeer half of our two-car garage for the project. We began by lofting the hull as a chalk outline on the concrete garage floor. Next, we constructed a 16′ structure of four 1″x 2″ pine longitudinal stringers with several rectangular 1/4’’ marine plywood bulkheads spaced along their length. To reduce weight, we cut multiple circular holes into each of the bulkheads. Despite trying to bend the 1 x 2s using hot water, we were unable to create the desired taper for the forward sections of the hull. Instead, we made several oblique scarf joints to form the proper curve. We affixed sheets of 1/4’’ plywood to the sides and transom
With the hull resting inverted on sawhorses, we shaped Styrofoam into a semicircular canoe underbody using a disc sander. We then applied fiberglass cloth and epoxy resin, as Styrofoam is dissolved by polyester resin, to cover the smoothly contoured foam. This long, narrow, slab-sided hull caught the attention of all passers-by on our busy street because it looked like a coffin more than anything else, and when asked, we generally told people that it was indeed a coffin. After a couple coats of white paint, the hull was complete.
Excited, we transported the hull, protruding from the back of a friend’s station wagon, down to Lake Michigan to test the seaworthiness of our homemade vessel. When we walked it into the lake from the beach, it floated exceedingly high and was intrinsically unstable, with or without one of us aboard, immediately rolling onto its side if let go. But this did not deter us. We were delighted it floated at all.
Constructing the lifting hydrofoils came next. We decided to build surface-piercing, self-regulating foils rather than fully submerged foils. They would have dynamic stability without requiring moving flaps to adjust their position in the water. After considering several NACA (National Advisory Committee for Aeronautics) foil cross-sections, we decided for simplicity’s sake to use ogive sections: circular-arc upper-surface contours and flat undersurfaces.
In the early 1970s, Philippine mahogany was cheap and abundant, as well as beautiful. For strength, we chose to build our foils of long, laminated wood strips as one might do for a cutting board. The foils needed to be tapered, necessitating a complex cutting schedule for the 250 strips to be laminated. Through Marty’s father, we gained access to a woodshop, where we obtained enthusiastic assistance from an old German modelmaker named Arthur for a full day of ripping and tapering the mahogany. We painstakingly assembled the laminates and glued them together with resorcinol. We also laminated mahogany strips for the streamlined supporting struts. To provide additional lifting force in the event of an excessively deep submersion of one of the main foils, we also incorporated hand-contoured pine “safety-foils” into the complex main assemblies. We mounted these transverse foils well above the main foils to provide additional lift if the boat heeled enough to immerse an entire foil assembly.
A few people got wind of our unusual, intriguing project and volunteered their support. The father of one of our friends owned a pinball machine manufacturing company. He generously donated two large sheets of 3/32″ stainless steel which we used to reinforce the main foils. Louis’s brother-in-law gave us two 10′x 2″ aluminum electrical conduits to use as supporting beams for the port and starboard main hydrofoils. These conduits acted as the spars for the main foil arms. They mated to the hull through reinforced holes traversing the beam of the hull. The circular section of the conduits allowed the main foils and their entire assemblies to pivot about the transverse horizontal axis. Rotation of these conduit beams permitted adjustment of the foils’ angle of incidence, and enabled us to rotate the foils completely out of the water.
The most innovative feature of our hydrofoil sailboat was the bow foil. The vertical “rudder” was laminated mahogany. The V-shaped bow foil assembly was made of hand-contoured aluminum plates along with a V-shaped pine “safety foil” mounted above it. The entire complex was suspended by gudgeons mated to inverted pintles attached to the plumb bow.
A retaining pin through each pintle helped to keep the rudder in place. The underwater portion of the rudder, with its V-shaped foils, was cleverly angled aft so that its center of resistance would be located aft of the vertical pivot axis on the stem giving it a caster effect for directional stability. We installed a vertical joystick in the aft cockpit and linked it to the rudder/foil complex at the bow by steering cables and pulleys.
We worked diligently through many long nights assembling, fiberglassing, and varnishing all the parts. The end of the summer approached quickly. It was time for the second launching, to test the hull and all the foils together, but—still without a sailing rig—a towing test made best sense. We erected a temporary wooden frame with a rudimentary mast “stump” to act as a towing post near the anticipated center-of-effort of the future sail plan.
Once again, with the help of many interested onlookers and friends, we transported the hull and the three foil assemblies from my house to the beach. Waves ranged from 1′ to 2′, higher than ideal. We carried the boat out into deep water. A small outboard runabout from our sailing club served as a satisfactory towboat. I climbed aboard our hydrofoil sailboat, secured the tow rope to the stump, and the test commenced.
At my signal, the tow boat shifted into gear and very slowly accelerated. A friend aboard the motorboat directed his Super-8 movie camera in slow-motion mode toward our hydrofoil. I signaled the boat to go faster. At about 4 knots, the bow rose majestically from the water. The vessel’s attitude resembled a long jetliner rotating for takeoff. I stepped forward in the hull to shift my weight toward the bow. As the tow accelerated more, the entire hull lifted free of the water. For the first time, we knew with certainty that the foils could provide sufficient lift.
I then turned the hydrofoil to port to determine if the steering mechanism worked and to see how the craft behaved with the tow rope force directed from one side, 30–40 degrees off the bow. This side force, pulling near the center of effort of the anticipated future rig, simulated the forces of sailing and tested both directional stability and reaction to an applied heeling moment. Indeed, the vessel tracked well and the self-correcting forces created by the surface-piercing main foils prevented the boat from heeling. The hydrofoil cruised along parallel to the port side of the motorboat’s wake, but after a few seconds there was a great explosion. The pull on the temporary rig ripped the hull apart and one of the main foil arms failed, causing the flying hull to crash down onto the surface of the water.
The structural failure was a major setback, but the test had been a success. Watching the successive explosions of Elon Musk’s Starship prototypes now, in 2021, makes me realize that even with the crash, our prototype experiment was truly a success. Albeit on a smaller scale, our successes and failures were comparable to those experienced in multi-billion-dollar engineering projects. Like Musk says: “It’s weird if it doesn’t explode, frankly.”
In the summer of 1973, Louis, Marty, and I reconvened to repair, improve, and further test our hydrofoil, this time with a sailing rig. Although we had great ideas for an innovative wingsail, simply reconfiguring and strengthening our vessel demanded our full attention given that we only had the three months of vacation to work on it. We fashioned aluminum deck braces to strengthen the undecked hull. After analyzing the forces that had led to foil-arm failure the previous year, we attached guy wires of slender stainless-steel cable for additional strength. We incorporated several other small modifications to the simple vessel that had marginally passed our first proof-of-concept test.
With no time to construct a wingsail, Louis, Marty, and I decided to cannibalize the mast, boom, and sails from one of our Albacores. We added a cross strut made of aluminum conduit—again, donated by Louis’s brother-in-law—to provide a wider base to anchor the port and starboard shrouds. Next, we provisionally assembled the entire craft on my front lawn to ensure that all the parts fit together and seemed sturdy. It was an exciting moment as we admired with pride and photographed our ungainly contraption.
We waited for a day when the lake was not too rough, but still had enough wind to induce our invention to rise above the waves. A handful of friends and curious sailing-club members got wind of our hydrofoil sailboat and most deemed this to be a madman’s folly. Some sailors at the club even ridiculed us. Nobody in the area had heard of, let alone seen, a hydrofoil sailboat. Naysayers consistently scoffed at us, declaring that the feat would be impossible. The mere appearance of our flimsy-looking assemblage of seemingly random materials elicited fits of outright laughter.
We had our own doubts, as well. None of us had seen a hydrofoil sailboat or even spoken with anyone else who had. We knew that we were on our own and had spent hundreds of hours climbing way out on a limb. It was an act of blind faith. I had trouble sleeping the night before the launch, as I reviewed in my mind every detail of the planned test. We started early in the morning, transporting all the components to the beach. We cautiously inserted the foil arm spars through the hull, stepped the mast, bent on the main, and hanked on the jib. Everything fit.
A group of us walked the boat from the beach into deeper water. Marty swam to the bow and attached the bow foil and steering assembly, securing the pintles with their retaining pins. Our crude calculations indicated that the boat would work best with one person aboard. Accordingly, the three of us took turns hoisting the sails, adjusting the angle of incidence of the main foils, and attempting to sail.
Louis went first. The wind was light, at most 5-to-7 knots. The contraption sailed slowly but smoothly, proving that it could advance on all points of sail while in displacement mode. The rest of us watched eagerly from a Boston Whaler as a Louis maneuvered for about an hour without getting any lift from the foils.
Next came Marty’s turn with little additional success. The bow foil lifted the forward end slightly, but not much more. By the time my turn came, the wind had picked up to around 10 knots. I had trouble trimming the main and jib while simultaneously steering. I had Marty climb back aboard with me while I increased the angle of incidence of the main foils. We were getting desperate—time was passing and our naysayers were beginning to gloat.
While I was near the stern clenching the joystick and Marty sat amidships trimming the sails, the wind came up to 12 knots. The bow rose and Marty moved forward to correct the fore-and-aft trim, further optimizing the foils’ angle of attack. As he sheeted in both sails, I steadied our course on a beam reach. The boat accelerated smoothly in response. The hull pitched rhythmically in the chop. Distinct vortices formed along the trailing edges of the main foils.
Suddenly, as though by magic, the entire hull rose from the water and our boat shifted into another gear. The choppy ride instantly became smooth and swift as though gliding on ice. On the Whaler, Louis had the Super-8 camera rolling to document the event.
This flight only lasted a matter of seconds before another catastrophic main arm failure caused the hull to drop precipitously back to the surface. Nonetheless, we had done it! We had flown above the waves under sail with two people aboard. Louis, Marty, and I, as well as the two or three others who had witnessed the event were wildly ecstatic. During our simple proof-of-concept test, we had harnessed the forces of wind and water to accomplish a pioneering feat of physics. Although we never pursued our project any further, this event and the incomparable euphoria of our Wright Brothers moment live on as one of the greatest experiences in my life.
Mike Jacker is a retired orthopedic surgeon who lives in Highland Park, Illinois, with his wife, Laurie, their 30-year-old African grey parrot, Zeke, and their Brittany spaniel, Max. He cruises during the summer on Lake Michigan aboard JOLIBA, an Ericson 38, and also sails a Vanguard 15. In addition to sailing, Mike enjoys kayaking, flying sailplanes, boatbuilding, dancing, and photographing local wildlife. He recently published a book, Taken by the Wind, chronicling a year-long voyage to the South Pacific in 1976–77 aboard a 30′ sailboat before the advent of GPS.
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