High-Tech Boat Testing

Boat Tests


  • Donzi
  • Donzi Roscioli R-73
  • 2017
  • Sportfisherman
  • 2/Cummins Onan 27.5-kW
  • 73'0"
  • 19'6"
  • 5'0"
  • 86,000 lb.
  • 2/2,000-hp MTU 16V-2000-M91s
  • 2,400 gal.
  • 320 gal.


Air temperature: 85°F; humidity: 80%; seas: 2'; wind: 6-8 knots


1,700 gal. fuel, 100 gal. water, 5 persons, 800 lb. gear.


2/2,000-hp MTU 16V-2000-M91s

ZF 3055A w/ 2.03:1 gear ratio

38 x 50 5-blade CNC-cut NiBrAl Michigan Wheel Marlin Series

The Numbers

Roscioli Donzi R-73 - Final Boat Test Numbers:
600 7.0 7.4 204.3 0.3
1000 11.3 35.0 697.0 1.9
1500 21.0 95.0 477.0 3.4
2000 33.0 163.0 437.0 3.7
2075 35.0 178.0 425.0 3.5
Speeds are two-way averages measured with Racelogic V-Box. GPH taken from MTU engine display. Range based on 90% of advertised fuel capacity. No sound levels measured. Sensors not available at time of sea trial.

Why isn’t your new yacht making her contract speed? Why are her turns to starboard tighter than those to port? Answering such questions definitively has been virtually impossible over the years.
Not any more.

Scientific Expert Analysis, or S-E-A Ltd., is an American enterprise that’s been doing forensic analysis and investigative research for more than four decades. Today, S-E-A has approximately 260 employees, most of them highly credentialed engineers and scientists who deal very precisely with a variety of concerns, from the vicissitudes of hydraulic fracking to the safety of candles for sale on the open market. 

Although S-E-A is a multidisciplinary player, the venerable company has remained quite focused over the years. It performs automotive-related rollover and crash simulations and testing for the National Highway Traffic Safety Administration and other governmental agencies. It designs and sells sophisticated testing equipment to corporations like Ford, General Motors, Nissan, and Toyota. It investigates accidents arising from mechanical, chemical, metallurgical, electrical, and fire-related causes. And it provides expert legal testimony, relating to a host of topics, all over the world.

Eric Sauer Eric Sauer wires up S-E-A’s data-acquisition module in our test boat’s engine room.

Recently, however, a new wrinkle’s been added at S-E-A, albeit one that arises from its forensic roots—a high-tech boat-testing program that promises great things for custom and production boatbuilders, high-end yacht buyers and owners, engine and propeller manufacturers, and even naval architects and marine designers. The program is headquartered in an office and laboratory complex in Ft. Lauderdale, and staffed by a cadre of former professional mariners, retired U.S. Coast Guard and Naval officers, and salty young mechanical engineers. And it’s outfitted with a veritable arsenal of super-sophisticated data-acquisition equipment.

“We’re focusing on yachts with this program—big boats,” says ­S-E-A spokesperson Capt. Chris Karentz, a Massachusetts Maritime Academy graduate who holds an unlimited tonnage, open-oceans master’s ticket. “I mean, think about it. If you’re planning to drop a few million bucks on a very technologically advanced vessel, or you’ve already purchased such a vessel and she’s underperforming, doesn’t it make sense for us to come in and do some testing for you, using a level of technology that is also advanced?”

Extraneous Variables? No Sir!

the box Racelogic’s V-box on the Roscioli Donzi R-73’s flybridge.

Karentz and I had dinner together last year, during one of the big boat shows, because a mutual friend thought we’d hit it off. After all, we’re both maritime academy graduates who worked at sea professionally before switching to different but related careers. And we’re both very interested in boat testing or, more particularly, forms of boat testing that are up to date, scientific, and innovative.

“S-E-A’s doing a practice or demo sea trial on a new Roscioli Donzi R-73 later this coming summer—Roscioli’s partnering with us, making fuel, a skipper, and time on board available,” said Karentz toward meal’s end. “It’ll showcase all our data acquisition system’s bells and whistles, or most of ’em. The idea is to check out the boat and our new equipment at the same time and see how everything works. You should join us. See what you think.”

I jumped at the chance. The R-73 is a solid, mainstream sportfisherman, with a nicely proportioned propulsion package (two 2,000-hp MTU 16V-2000-M91 diesels) and an excellent pedigree dating back to a 1998 introduction. Karentz had chosen her, he said, because of her predictable nature—he wanted a test platform that would produce reasonable, odds-on performance information that could be used to validate (or disqualify) both the boat and S-E-A’s whopping array of equipment.

“No sense fooling around with a problem boat at this stage of the game,” he said, “because then we’d get results that would be all over the place, which would mean having to chase a whole bunch of extraneous variables and maybe miss out on some good baseline data.”

Here’s just a bit of the data we recorded on the R-73, graphically represented.

turning radiusA disparity in turning radius is probably indicative of rudder issues.
Acceleration Curves An optimal acceleration curve with no performance-robbing bumps means the R-73 is nicely balanced.

(Click on image to enlarge)

Behold: The VPM

I arrived dockside at Roscioli Yachting Center in Ft. Lauderdale at 7 a.m. on a warm day last August to find S-E-A’s Bryan Emond (a retired U.S. Coast Guard commander and Naval Postgraduate School mechanical engineer) already at work on the foredeck of the 73. Emond was setting up three, suction-cup-accoutered antennas for a Racelogic V-Box system. S-E-A uses V-Box (with its super-fast, super-accurate differential GPS) to very accurately measure and record vessel dynamics under way, like speed, running attitude, acceleration, turning radius, G-forces, yaw, pitch, roll, and heel in turns. I was familiar with the technology—automotive magazines have been using it to test cars for years. In fact, I’d used V-Box to sea trial a few boats myself, but finally taken a pass on it due to cost and the time-consuming complexity of even a temporary installation. 

“The V-Box is a big part of what we call our Vessel Performance Mapping System, or VPM,” explained Emond as he plugged in a long, gray CAN data cable with a military-spec connector. “And the other big part is the multi-channel data acquisition module. Eric Sauer’s wiring it up right now, down in the engine room.”

When I first caught sight of Sauer, he looked like a mad scientist in the midst of a crazy experiment. He hunkered over a large Pelican case, on the walkway between the MTUs, amid the multi-hued auras of blinking lights and infrared-tachometer beams, apparently securing strain gauges to the 73’s two Seatorque propeller shafts. The gauges, he explained, would measure and record the exact amount of physical twist each shaft would endure at numerous rpm settings during our upcoming sea trial. These findings would be used to quantify the amounts of power available to the props at all the settings, so those numbers could be compared with actual engine outputs, to discover any and all parasitic power losses within the reduction gears and other aspects of both drive trains.  

“These Seatorques caused a little complication,” said Sauer, looking up from what he was doing. “Had we been dealing with plain, solid shafts made of Aquamet 22 or the like, we could have simply done some calculations to get the baseline info we needed for the strain gauges to function properly. But because the cross-sectional area of a Seatorque is not uniform from a materials standpoint, we had to put an actual Seatorque system under physical load at our lab here in Lauderdale a couple of weeks ago to establish the baseline.”

The phantasmagoria of components and cables Sauer was installing looked pretty darn complicated as well, I told him. Beyond the Pelican case’s foam-cushioned engine-data gateways, panels, connectors, and MFDs, I eyed a veritable slew of thermocouples, pressure transducers, potentiometers, and other sensors mounted about, all set to instantaneously record (at a rate of 20 times per second) exhaust-gas pressures and temperatures, air temperatures and pressures, relative humidity, and thousands of other parameters.

“We’ll also be capturing all the data that each engine’s ECM [Electronic Control Module] spits out,” Sauer said, by way of acknowledging my observation,  as he removed a plug in a giant exhaust elbow so he could secure a small, jewel-like thermocouple. “And we’ll come away with hard, recorded data, not just the live stuff that momentarily appears on the instrument panels topside.”

High Tech on the High Seas

Max Heel in Turns Modest levels of heel, and modest G-forces as well, mean high-speed turns were both transversely stable, comfortable, and safe.

Getting the 73 ready for our offshore jaunt took Karentz, Emond, and Sauer, as well as a couple of other guys, a little over six hours. And the actual sea trial, with Roscioli’s Capt. Richie Koch at the helm, was quite similar to the sea trials Power & Motoryacht routinely does, with straight-shot reciprocal runs generated by specific data points, 360-degree turns to port and starboard, and a variety of S-curves dependent on sea state. But hey, there was a whole lot more high-tech equipment on hand, way more guys doing the testing, and, last but certainly not least, a wholly stunning accumulation of rock-solid data that quite literally brought the whole affair to the cutting edge of 21st-century boat testing.

S-E-A’s V-Box, for example, had determined that the 73’s average turning radius during high-speed (34 to 35 knots) turns was 572 feet when going to port but only 490 feet when going to starboard. Karentz addressed the sizable difference after our sea trial. “It’s possible that a variation in operator input is responsible, something we can rule out with an Automatic Steering Controller or ASC at a later date,” he said. “But I’d say it’s more likely that a steering-hydraulics issue is keeping the rudders from achieving full travel to port. We’ll see.”

And then there was the exhaust issue. Because of a slight disparity between the exhaust-gas pressures recorded on each diesel during our sea trial, S-E-A’s engineers discovered a balancing problem that was subtly affecting the 73’s sophisticated Von’Widmann underwater exhaust system. “When they even out the two sides,” said Karentz, “that’ll impact the longevity of the MTUs in a positive way. And it may even improve performance.”

And finally, two very basic performance parameters seemed to be  pointing out an age-old problem. The 73’s top speed of 35 knots at a WOT rpm of 2075 was well below optimum. “Most likely bottom fouling is the cause,” said Emond after the test. “We should have done closer to 40 knots at 2300 rpm. The pitch of the props could be off as well. Further testing’s indicated.” 

Once we’d finished up that afternoon, Karentz and I had a heart to heart. And it turned out we were in total agreement concerning two major aspects of S-E-A’s new boat-testing program. First, there’s no question that the program’s complexity—and the time required to manage it—precludes an average boater’s involvement. Three guys spent approximately ten hours (that’s thirty man-hours) sea trialing the R-73. Although Karentz maintains that a total of eight hours (and sixteen man-hours) will likely do the trick once things are more streamlined, we’re still talkin’ a hefty chunk of pricey time here, at least for an owner of a 30-footer or even a considerably larger boat.   

And how about the expense? 

“It’s hard to say exactly how much a test is going to cost,” said Karentz, “because you don’t know what you’re going to run into. But I guess it’s safe to say that performing a full trial on a boat like the Roscioli Donzi R-73—which is a very good [translate: very easy-to-sea-trial] boat, given the minor nature of the few issues that came up—is going to cost something like $10,000.”

A considerable sum? Indeed, but then again, if a guy’s thinking about spending several million bucks on a yacht, or maybe seriously concerned that said yacht is not performing the way she needs to, it’s altogether possible that Karentz and his buddies at S-E-A are absolutely right. A day or two of high-tech boat testing may be well worth the investment.

S-E-A, 888-771-0591; www.sealimited.com

Click here for Donzi’s contact information and index of articles ▶

This article originally appeared in the February 2017 issue of Power & Motoryacht magazine.

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