Sunday, November 12, 2006
A Brief Lesson in Marine Engineering This little memory just popped into my head this weekend while watching efforts to recover a Fire Department air boat in a nearby town. It's a short tale with a bit of a cautionary message to any aspiring marine engineers or designers. This would fall into the "lessons learned the hard way" school of thought. The photos above show a little of the building and operating of a small "hydroplane" style boat that is fairly easy to construct and operate. Usually. When I was about to go into high school, uncle R let up a little on the chores and allowed me to do a couple jobs away from the farm to earn some pocket money. At that time, labor laws were really non-existant or loosely enforced. I was already delivering a number of daily papers every morning while my aunt delivered milk. As soon as R told me I could look for an additional part-time job for the summer if I so desired, I was off and running. By the evening of the first day of job hunting I'd secured a job in a local hot dog stand that was regionally famous for its meatball style sandwiches. These consisted of a sausage-shaped meatball in a hot dog bun with spaghetti sauce and cheese. There was also the usual variety of hamburgers, hot dogs, etc on offer. That, however, is unimportant to this story, other than the fact the stand employed another lad who was a friend of mine. This other lad lived on the lake we had our summer cottage on, only he was a bit farther down in another part of the lake and lived there year-round. He and I had known each other for years in school, although we were never close as we were a year apart in grades. As a result of his living so close to the farm and working with me, we struck up a close friendship and started spending a lot of the few free hours we had together. One thing led to another, and soon he was helping me on the farm and with my paper route in exchange for guaranteed transportation to and from town to work in the food stand. The pay wasn't high, but we had simple tastes and it included all the food we wanted to eat at work. One neat rule was that you "ate your mistakes". After work and on days off, we found ourselves spending many hours together. One thing about two young fellows with a combination of spending money, access to a machine shop, access to a garage with a woodworking shop, and free time, is that they will eventually find a way to combine all these factors to amuse themselves. We were no different. As I started spending some time at his house, we got nosing around his dad's woodshop. His dad was a truck driver and often gone for weeks at a time earning a living. This left the woodshop at our mercy. Eventually, while poking around in the stack of magazines in the shop, we stumbled across an article that detailed plans for constructing a hydroplane. What a great idea. We had a lake, woodshop, time, and ability. What a wonderful thing we'd decided to do, construct a hydroplane and use it with his dad's little outboard motor. The plans called only for things we had at hand, and we felt we were blessed with more than adequate building talent. As luck would have it, his dad had a generous supply of marine quality plywood sheets of various thicknesses. Uncle R had all the raw materials required to construct the engine mounting fittings, steering components, and other assorted metal parts in his machine shop. He even had the steering wheel of an old tractor somebody gave him hanging on the wall. My friend's dad had glue, fasteners, caulk, clamps, work benches, etcetera. We were good to go. Over the next two weeks or so, our desires, energy, talents, and a lot of trial and error, resulted in the completion of a small hydroplane similar to the one shown above. We were walking on air and filled with excitement as late one evening, having determined the craft was water worthy, we wheeled it on his dad's utility trailer across the lawn from the shop to the dock. His mom, sisters, cousins, and uncle were all there to see the launch. Actually they were simply swimming, but we took their presence as a ready-made cheering section as we manhandled the little boat to the edge of the dock and into the water. Success, it really floated. Having this good fortune buoyed our egos and we decided we'd tie it to the dock and wait until the following day, a Sunday, to add the finishing touches and give our little marvel a proper test run in the daylight. It being a Sunday, and himself in a really good mood, uncle R and F decided to come see the terrific little boat I kept going on about. As soon as morning chores were completed, we were off in the old farm truck. My pal's dad had a small aluminum fishing boat with a gas tank and ten horsepower outboard motor. Just the exact thing our creation was designed to have as the maximum sized power plant. We put the gas tank full of fuel in its holder first. Still afloat. Add driver, still good. Last touch, uncle R helped me transfer the outboard from one boat to the other. Miracle of miracles, still on top of the water with driver, fuel, and motor. What a coup this was. My friend started the motor, sat at the wheel, reached back and shifted into gear, and slowly added power. The little craft moved smartly away from the dock. Now gaining in confidence, he gradually put the boat through its paces, testing its limits and agility. Everything was a great big success. After zipping around the cove for about ten minutes he pulled up to the dock grinning from ear to ear. He gave me a quick rundown on the finer points of the handling aspects and I was aboard and off. What a sensation! This thing was a true marvel of marine construction. We spent the rest of that day playing with our new toy and showing off our expertise. All was well with the world and all things in it. Monday was a work day with no time to play on the lake. We still went to his house in late evening to admire our little vessel. On arriving at the dock, we found our boat had been joined by another, larger craft. Seems my friend's uncle had just bought a sixteen foot run-about with a forty horsepower Mercury outboard. We checked it all out, started the motor, and generally ignored our own smaller toy. The following day we both had free time after chores and decided to resume playing with our new gadget. On arriving at his house we found a note from his mom saying they'd all gone to the city and would return the following day. This set the stage for the disaster that was soon to befall us that sunny day. After playing with our boat and discovering we could operate it at its maximum limits of power easily, we started doing that most dangerous of all things for young boys to do. We started speculating and theorizing about how to get more performance from the little boat. We discussed and discarded several ideas before hitting upon the obvious solution that stared us in the face. Bigger motor, more performance, maximum fun! His uncle's boat with its slim, sleek, enticing, forty-horse Mercury was just begging us to notice it. As it was, we both hit on the idea simultaneously. A few quick calculations, completely ignoring the instructions about ten being maximum horsepower for the hydroplane, and we were all set. The motor would fit, it didn't seem much bigger than the bulky motor with less power, and we were certain it would be fine. Having convinced ourselves of our genius, we quickly made the motor swap. This was a true stroke of genius! The first thing we noticed, which would have tipped off wiser heads to a problem, was that the little boat was a tad rear-heavy. As my friend started to assume the driving position, the back of the boat crept perilously down in the water. He promptly exited the boat and we started brainstorming how to solve the problem. After a few minutes of discussion, we decided the solution was for myself to carefully hold up the rear of the boat until sufficient power was added to propel it forward. We had decided, correctly as it turns out, that once in motion the plane blades and propeller would eliminate the sinking tendency caused by the heavier motor's weight. We were true mechanical and boatbuilding whizzes! The best! Sure enough, as he started the engine and gradually added power in gear, the weight lessened on my arms from supporting the thing. As I felt it safe and let go, the little boat smoothly pulled away from the dock. Soon my pal was having the time of his life guiding our now high performance craft about the lake. After about ten minutes of watching I signalled for my turn at the helm. Seeing my signal, my friend abruptly swung the boat about to return to the dock. As he did this, he hit the waves from his own wake at an angle, allowing a large quantity of water to enter the craft. This in itself wasn't fatal to the little vessel, but my pal's inexperienced reaction was devastating in its effect. He abruptly pulled back on the throttle lever, thinking to slow down & recover control. Unfortunately, this, in combination with a sudden sloshing of water over the engine, was enough to cause a sudden stoppage of all motor activity. And yes, fifty feet from the dock, in about thirty feet of clear blue water, our little jewel found its way under the surface of the lake. My pal, wearing his bulky life preserver, slowly made his way ashore, and there we sat. Two shell-shocked young boys, with absolute knowledge that when the uncle returned we were goners. That was one of the most miserable afternoons in my memory. We were so totally devastated that we sat there long past evening chore time. When I failed to show for chores, F came seeking me out. When we told him what had happened he abruptly sat down on a lawn chair speechless. My pal's uncle had much the same reaction. Although we recovered the little boat and paid for repairing the engine, neither of us recovered enough from our mistake to resume our budding careers as marine designers. Until next time, take care.
Posted by Mike S at 9:32 PM