|The Extra Mile|
of dollars...the latest equipment...diesel-fuel showers...
there's a lot entailed in putting together meaningful boat-test data.
By Capt. Bill Pike — June 2000
Here at PMY, there's more to testing boats than meets the eye. On one level, the process seems straightforward: The idea is to collect and present solid, independently derived performance data that's useful to readers. But doing the job well requires a complex step-by-step methodology that's structured, scientific, and time-consuming, especially since such a large part of PMY's editorial focus is large and complex diesel-powered yachts and sportfishermen.
A boat test typically starts with mechanical work. The PMY tester shows up alongside the test vessel on the appointed day and immediately begins bilge-crawling its engine room for 15 minutes or so, scoping out the powerplant installation and fuel system. Next, he breaks open the supply and return fuel lines (only one line if it's a gasoline engine) on one of the engines and installs fuel-flow measuring devices on each using a dizzying array of wrenches, nut-drivers, and other tools as well as a slew of hoses, tie-wraps, and fuel-absorbing pads.
With the fuel-flow meters in place, he now connects each of them to a cigar-box-size computer via cables and the computer to the vessel's batteries via another cable. If properly set up, the computer will convert electronic impulses generated by the fuel passing each meter into gallons per hour, do the requisite math, and display the instantaneous net fuel usage in gallons per hour on the computer's display. After hand-pumping out all the air from the engine's fuel system to prevent time-consuming air-lock horrors, he fires up the engine and checks for fuel leaks and other glitches.
Finally, it's time to test. The PMY tester cranks up the other engine (if there is one), gets behind the wheel--with computer, Stalker ATS radar gun, and sound meter at the ready--and with assistance from a chart and/or person with enough local knowledge to obviate a grounding, eases free of the slip and heads for the open water. There he will record fuel-flow figures, radar speeds (on reciprocal courses toward a fixed object like a bridge or rock outcropping), and sound levels at a variety of rpm settings. He will also measure acceleration using a sophisticated computer program linked to the radar gun, taking the average of four runs. The final step is the most enjoyable: wheel time. He puts the boat through a series of maneuvers to judge throttle response, seakeeping, turning radius, and other handling characteristics.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.