October 22, 2015

When boatyards built engines

IT’S ALMOST EXACTLY 100 years since one of the most famous American small-boat architects designed and built a wooden boat called  Cabrilla. William Atkin and his boyhood friend Cottrell Wheeler were the owners of a small boatyard on Long Island, New York, and Cabrilla was the largest boat they built there. She was a high-speed express cruiser, 115 feet in overall length.

But one of the most interesting things about her was the fact that young Atkin and Wheeler themselves designed the twin V-8 gasoline engines that powered her. Not only that: they built the engines, too, and installed them of course.

Atkin said later in his book Of Yachts and Men:  “Reviewing those days . . . I am astonished at the work we undertook and produced. The design work on Cabrilla was no small item.” This, naturally, was long before the days of computers, or even calculators, and all the work was done with pencil, paper, drafting ink, and the human brain.

Atkin described those engines as “big fellows of more than usual interest.” Each was of V-type with eight cylinders. The cylinder bore was 8 inches and the stroke 14 inches. Each bank of four cylinders was cast en bloc and, to insure perfectly even cylinder walls, was cast without the water-cooling jackets; the jackets were fitted to the cylinder blocks after all the machine work was completed.

In his book Atkin says: “The crankshaft was a steel casting and turned on Hess-Bright ball bearings, three bearings to each engine. To give some idea of the size of the crankshaft: the races of the bearings ran on balls having a diameter of 2 3/4 inches. The inlet and exhaust valve sets were made of heat-treated steel and were removable. The exhaust-valve stems were cooled with sodium. All the reciprocating valves were closed by positive cams rather than by compression springs. The crankcase was of skeleton form, cast of vanadium bronze and had 1/16th-inch-thick Tobin bronze plates to cover the openings.”

Atkin used outside contractors to manufacture several parts of the engine to his designs, but hundreds of other parts were made and assembled in his own boatyard basement.

“Yes, shipmates, Cabrilla’s engines were big fellows,” Atkin reflects, “and when, in these later years, Cottrell and I contemplate the fading past, we marvel at our youthful courage in tackling this job, which then seemed very simple, but which if attempted now would embarrass the engineering department of a large corporation.

“Cottrell designed all the mechanical and electric fittings for the hull, the disk clutches and reverse gears, and supervised their construction. The design of the engines was my contribution to the work then in hand. All this we accomplished within nine months and without the assistance of draftsmen or additional help.

“Fortunately, Cabrilla was designed before the days of expeditors, industrial efficiency, inspectors, personnel managers, safety engineers and all the other complicated and expensive claptrap of present-day production confusion. If we had had the fellowship of today’s industrial top-heaviness and discord, the yacht might never have been launched at all.”

Today’s Thought

Often ornateness goes with greatness;

Oftener felicity comes of simplicity.

William Watson, Art Maxims


“Man, I never realized how short of living space the world has become.”

“What makes you say that?”

“Well, I came home early last evening and found a strange man living in my wife’s wardrobe.”

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)


Kevin Vigor said...

"The exhaust-valve stems were cooled with sodium."

Methinks these fellows could have used at least a *little* help from a safety engineer.

Jack said...


57 Degrees North said...

Safety engineer? Exhaust valve stems filled with a liquid sodium solution was a relatively common technique of creating a heat path to keep the valve face cool, allowing you to run higher compression ratios and thus higher exhaust gas temperatures. (In all, probably far less hazardous to machine/produce than melting lead for keels for Gossake.)Certainly far less dangerous to the public at large than the leaded fuels which served essentially the same function...