— By Capt. Bill Pike
— August 2003
|This well-crafted 48-foot convertible offers engineering, performance, and conservative good looks.|
From the cushy comfort of the helm chair on the flying bridge of Silverton’s 48 Convertible, I eyeballed conditions to the east with anticipation. Things looked pretty sporty out there beyond the St. Augustine sea buoy, sporty enough to give just about any vessel, barring an aircraft carrier maybe (or a nuclear attack submarine), a decent wring-out. A wind shift had started the melee. With a profusion of six- to eight-foot swells continuing to roll up the Florida coast, seas were starting to build from offshore.
Not long after overtaking a big, twin-engine Coast Guard RIB in the channel, with four wet youngsters onboard, all of them grim-faced and hanging on for dear life, I aimed an interrogative look at the Silverton rep sitting next to me. “Go for it,” he responded with the confident, enthusiastic smile of a guy who’s headed for a little weather while snugly ensconced within a nice, dry, optional Strataglass enclosure. I eased our DDEC electronic throttles ahead, slowly transitioning the test boat—a prototype equipped with a set of 825-hp MTU diesel inboards—from a laid-back lope of 12 knots all the way up to a full, Katie-bar-the-watertight-door cruise. Within minutes, the Raymarine RL80C Plus radar/plotter on the dashboard was reading 20 knots, and the head seas we were charging at were whooping over the tips of the outriggers!
“Don Blount designed the running surface,” yelled the rep as I swung the 48 into a long, graceful arc, first letting her beeline a couple of deep troughs and then steadying the bow up so the mixture of swells and seas were more or less abaft the beam. Blount, an increasingly popular designer with a background in military patrol boats and high-speed recreational planing craft, had done a superb job from what I could tell. The boat continued down-sea at approximately 20 knots with such unwavering steadiness, I found I could actually take my hands off the wheel for long intervals.
“Dang,” I marveled. Had Blount been onboard at the time, I’m sure he’d have attributed this performance to the savvy placement of the boat’s longitudinal center of gravity, or LCG. Then, with characteristic fervor and attention to detail, he’d have undoubtedly gone on to state that he currently situates most LCGs on high-speed planing boats like the 48 at a point “at least two percent of the projected chine length aft of the lifting center of the hull bottom,” to quote from one of his most recent technical papers. The benefits of applying such a seemingly prolix rule of thumb to the 48’s design were obvious to me at the time, but to fully explain the rule now and describe its origin goes well beyond the scope of this report, although the accompanying diagram (see below) may clarify things.
Prior to returning the 48 to a dock behind the Luhrs/Silverton plant in St. Augustine, I backed her into a nearby slip to familiarize myself with her close-quarters quirks and characteristics. Handling was easy, predictable, and quick, thanks to a set of 28x35 4-blade Nibral props with plenty of torque behind them and the smoothness of electronic engine controls. When I ultimately squeezed in behind the plant—alongside a floating dock between two other brand-new boats—I discovered the sightlines from the bridge were excellent both forward and aft. Moreover, the fact that there was a set of backup mechanical engine controls nearby—a safety feature that should be mandatory on all boats with electronic controls, I think—inspired confidence, as did the fact that the gauges and electronic instruments in the wraparound, tripartite steering console panels in front of me were easy to see and figure out.
This article originally appeared in the July 2003 issue of Power & Motoryacht magazine.