Without a Prop|
David S. Yetman
Dog Ear Publishing, 120pp, 14.95
I may be the most inappropriate boating writer to review David Yetman's Without a Prop, being an American Lit major who had to take high school geometry twice. But I am curious by habit and my interest was piqued by being aware that the Hinckley picnic boats that grace our Maine waters every summer are jet powered. These sleek and graceful symbols of "top of the heap" human achievement are far and away more impressive than any penthouse or private compound to me. Mr. Yetman offered me the opportunity to delve into the elegance of jet drive, if I could only fathom his book.
It all starts out well. Yetman states that he is a self-taught writer, engineer and inventor who has enjoyed a lifelong fascination with Benjamin Franklin. Turns out that Franklin sketched and described a water jet boat in his 1785 masterwork, Maritime Observations (which even in my narrow academic concentration, I never read). But Franklin was a postscript in the long and winding tale of the development of the jet drive we employ today. The first recorded evidence of the idea is attributed to Hero of Alexandria who left designs, in that city's great library, of various curiosities which included an "aeolipile", a combination working jet drive and steam engine.
Though Sir Isaac Newton never built a jet, his 1687 Third Law, "For every action there is an equal and opposite reaction" describes how such a machine would work. This axiom, combined with the notion that mechanical pumps are involved, helped the light to dawn on Marblehead for me. Keeping these to facts in mind, I read on about increasingly sophisticated experiments with water, temperature and pumping devices.
Virginian, James Rumsey showed General Washington a variation on the theme in 1784. In 1786 Rumsey tested a water-tube boiler system on the Potomac. It was so efficient it blew itself up. Tinkerers persisted. Finally, in 1931 Keenan Hanley of Detroit built the first practical commercially available water jet boat, used by city fire companies. By the early 1940s he was supplying the Coast Guard with fire fighting boats. (The steel hulls were designed by Sparkman & Stevens.) But jet powered boats didn't really get exciting until a New Zealander named Hamilton decided that jet drive technology was just what was needed for traversing the country's shallow and rocky streams. Hamilton's boats were built of plywood and sported a new type of propulsion, "an engine driven centrifugal pump which forced a jet of water out of a submerged nozzle" according to a 1953 article in Popular Mechanics. (I think I've got it!)
The most action packed chapter in the book describes the testing of little fiberglass runabouts driven up stream on the Colorado by similar engines. That test brought great attention to the new system and the rest is pretty much history. Today we have, on one hand, those lovely picnic boats elegantly jetting by and the swarms of jet skis buzzing around like angry hornets. They sure are fun but why can't they be muffled?
Without a Prop was a fun read for me, in spite of my trepidation. No mechanical description was unfathomable, schematics and diagrams were clear and simple. Yetman writes with a straightforward liveliness. What I feared would be an impenetrable foreign language was an eye opening education. And, wait 'til you see the photos of some of the turbo boats built in the 1950s and '60s, especially the Rumble, a 24-foot Virgil Exner (of Studebaker and Dodge Charger fame). She's powered by a 426 cubic inch Chrysler V8 driving a 3-stage Hamilton jet. She was discovered in a Montreal junk yard in pieces and faithfully restored.