MV Woods Hole glitches rooted in propulsion system

The ferry employs the only controllable-pitch propeller system in the SSA fleet.

The ferry Woods Hole will miss several runs Saturday night. – File photo by Rich Saltzberg

Updated April 24

Beset by glitches since grounding on March 15, the MV Woods Hole returned to service on April 6 after an international team of technicians was assembled by SSA officials to fix malfunctioning valves and propulsion controls. Both fixes were related to the ship’s complex controllable-pitch propulsion system. The MV Woods Hole, the newest Steamship Authority (SSA) ferry, is the only vessel in the SSA fleet with controllable-pitch propulsion, which affords the vessel increased maneuverability and stopping power. But the mechanical and operational complexity of the system also appears to be contributing to the ferry’s recurring woes.

Explaining the controllable-pitch propulsion system to The Times, Commodore Bradley Lima, senior vice president for academic affairs at the Massachusetts Maritime Academy, said the blades on a traditional boat propeller are fastened to a hub in fixed positions, like blades on a fan. If the fan were constructed like a controllable-pitch propeller, each fan blade would be able to rotate 180 degrees.
Initially there seemed to be a difference of opinion in what exactly went wrong with the MV Woods Hole propulsion system.

Steamship Authority general manager Robert Davis said that the valves that failed on the MV Woods Hole control the hydraulic fluid that pivots the blades on the propeller.

However, Mogens Christensen, managing director of Hundested, the Danish maker of the propulsion system, told The Times the failure was in a gearbox.

“Yes, the Woods Hole had a mechanical issue with one of the reduction gears,” he wrote. “A broken pin in a check valve results in slower than normal propeller pitch [pivot] adjustment. The vessel does not stop, nor is it out of control, but an alarm is triggered.”
Commodore Lima told The Times a reduction gear is a mechanism between the engine and the propeller shaft. Essentially, he said, propellers turn more efficiently at low speeds, and marine diesel engines operate more efficiently at medium to high speeds. The reduction gear bridges the torque between the two.

Davis reconciled Christensen’s diagnosis with his own in an email Tuesday evening.

“I am informed that the check valve is contained within the reduction gears,” he wrote.

Both managers agreed pins inside valves broke. Davis said four pins “snapped” in one propeller shaft. “Upon inspection some of the valves in the other shaft showed signs of failure and were replaced at the same time,” later wrote.  On Wednesday afternoon Davis clarified pins aren’t repaired in of themselves but replaced with the valves they’re part of.

On Monday, April 23, Christensen confirmed eight valves were replaced in total.

“We redesigned the pin and made it out of stronger material,” Christensen said.

Davis said redesign changed the pins from a tapered shape to a stepped shape.

When Hundested was contacted for the emergency repairs, the work was evidently done on short order.

Christensen said the Steamship Authority called for assistance on Friday evening, March 28.

On March 29, Hundested sent an engineer from Mexico to the Steamship Authority’s Fairhaven facility to install the valves, and dispatched a DHL courier with the valves, Christensen said.

On April 23 Christensen elaborated on the logistics, recalling that the Steamship Authority informed Hundested DHL may not be swift enough, so Hundested dispatched a staffer from Denmark with a separate set of valves.

The parts arrived in Fairhaven midday Saturday, Christensen said. “It took two hours to install.”

The valves transported by DHL didn’t arrive until Tuesday, Christensen said.

Davis said Steamship Authority engineers collaborated with Hundested’s engineer on the installation. Asked why SSA personnel didn’t install the pins, Davis said it was more efficient to work with the Hundested engineer.

EPA and ‘meantime between failures’

Ferries, as Brian King, vice president of engineering at Elliot Bay Design Group and former project manager for the MV Woods Hole, put it, are reflections of their engines. “They’re largely designed around the engines,” he said.

King’s firm also designed the MV Island Home, a traditional-propulsion ferry built in 2005 and put into service two years later. Elliot Bay couldn’t design the MV Woods Hole around engines identical to the MV Island Home because changes in Environmental Protection Agency (EPA) emissions standards no longer allowed that type of engine. To fit the new standards, Elliot Bay selected 2680 hp MTU diesel engines. These engines could not handle the torque of a traditional propulsion system, but worked well with a pitched propulsion system, King said, hence pitch propulsion was used.

A major side benefit of the propulsion system in the MV Woods Hole is the ability to swiftly stop the vessel in an emergency by throwing it in full reverse “without fear of stalling the engines,” King said. Emergency stops in vessels with traditional propulsion are slower and more complicated, and run the aforementioned risk, he said.

Commodore Lima agreed. Lima said a warship like an Arleigh-Burke destroyer can employ controllable-pitch propellers to achieve a full stop within two lengths of the ship. Many commercial vessels with traditional propellers need miles to do the same, he said.

But Lima noted benefits like stopping power and “a much larger degree of maneuverability in a much shorter time” can be offset by the costs associated with such a mechanically demanding propeller system.

Between 1977 and the mid-1980s, the Massachusetts Maritime Academy owned the Marathon, a 165-foot Vietnam-era gunboat that featured controllable-pitch propellers. Despite its value as a training vessel, the academy couldn’t afford to keep it. “The cost associated with keeping the controllable pitch operational was too steep,” Lima said.

The academy needed a full-time mechanical crew to upkeep the propulsion system, he said. Lima cited the military term “meantime between failures” (MTBF), a measurement of how reliable a piece of machinery is, to describe how often the Marathon required servicing. “Unfortunately, the MTBF on that vessel would be measured in hours, not days,” he said.

Evidently, not so with the MV Woods Hole. Davis noted it posed no problems for the first 19 of 20 months in operation. “By all accounts it’s a great vessel,” he said.

Conrad built a good boat,” Christensen wrote. “SSA chose good equipment to be installed.”

Hundested Propeller and Conrad Shipyard were found to be well-regarded in a Times review of maritime trade publications.

19 of 20 months-ish

As The Times reported in August 2016, the newly delivered MV Woods Hole came with a design flaw that created unreasonable bow wake at high speed or in shallow water. Earlier that summer, a photo of the vessel showed it nosing out of Oak Bluffs Harbor with a downward-tilted bow. Former Steamship Authority general manager Wayne Lamson said at the time that the bow wake phenomenon caused captains to trim their vehicle loads to offset it. Elliot Bay Design Group modeled changes to the vessel’s bow bulb, but ultimately recommended changes to the spray rails. The Steamship Authority appears to have made the spray rail modifications on its own.

“Every ship is a prototype,” King said. “There’s a certain amount of fine-tuning that has to take place in any ship design.”

Stick shifts and ‘comfort zones’

Operation of a controllable-pitch-propulsion vessel is markedly different from a vessel with traditional propulsion, Commodore Lima said. He likened the differences to standard and automatic cars. For a captain who’s never been at the helm of a vessel with controllable pitch propulsion it’s like getting behind the wheel of a stick shift for the first time, he said — it will take time to learn.

The senior chief engineer and senior captain had responsibility for training the MV Woods Hole captains in the use of the controllable-pitch propeller system when the vessel debuted, Davis said. Now captains assigned to the vessel shadow the operating captain in the wheelhouse and ask questions to get a handle on the system, he said.

In a report to the Dukes County Commissioners on April 4, Steamship Authority board member Marc Hanover, the Vineyard’s representative, noted different captains of the MV Woods Hole operate the vessel differently. “You know on the Woods Hole — we’re having issues with the Woods Hole — they found out three different captains were operating the boat in three different modes. I don’t know if all of this has been mechanical. I think some of this has been training. This is why I want to bring somebody in from the outside,” he said.

Later, when asked about variance in how captains operate the MV Woods Hole, Davis said, “Each captain operates in their own comfort zones.”

Asked if captains had a training manual for the MV Woods Hole, Davis did not answer directly, but said captains have been able to consult with technicians in recent weeks from Hundested Propeller and Prime Mover Controls, a Canadian controls and instrumentation maker.

In an interview Tuesday, Hanover reiterated his wish to tap a consultant who could review SSA training and management to see where improvements could be made. Hanover said the SSA has a diligent, dedicated workforce, but the ferry service’s logistical scale and technological complexity may have outpaced those workers in recent years.

At the Dukes County Commissioners meeting earlier this month, it was suggested to Hanover that he also lobby for an electronics consultant. “I hear what you’re saying,” he said referring to issues with the MV Island Home, “but these electronics are made all over the world. And like this gentleman from Denmark, they wouldn’t give the codes to get into the system; they sent their man, which makes no sense. We’ve had issues with the engines before, and the engine manufacturer will call up and give you the codes to get in so you can correct it. These people would not.”

Hanover told The Times on April 23 it may not have been the engines. He was unsure what component of Island Home required codes but said the fact Steamship Authority personnel could not fix the problem on their own troubled him. Davis said on April 23 the technician Hanover referred to was from bow thruster manufacturer Tees White Gill, an English company. The technician did travel from Copenhagen, likely because another client was receiving service there, Davis said. Tees White Gill technicians had attempted to install software previously, Davis said, but the install failed. They dispatched the technician from Copenhagen to effect a reinstall and to address some other bow thruster issues, Davis said. Tees White Gill has since given the Steamship Authority the software for the bow thrusters to facilitate in-house troubleshooting, Davis said.


The slow-speed grounding of the MV Woods Hole on March 15 stemmed from a loss of control when steering was transferred from the wheelhouse to the bridge wing, an exterior balcony a vessel can be piloted from. Technicians from Prime Mover Controls were summoned shortly afterwards to suss out what might have happened. An ongoing Coast Guard investigation, which is expected to take months, is attempting to do the same.

Prime Mover Controls general manager Michael Combs declined to comment about the MV Woods Hole or MV Island Home.

Steamship Authority problems notwithstanding, King described Prime Mover Controls as a “quality outfit.”

Asked if valve failure contributed to the grounding, Davis said, “We’re still investigating what, if any, role it may have had.”

Concerning the valve pins, Christensen said, “Normally it is something you’d never touch in a lifetime.”

Davis said on April 23 that the Steamship Authority is also investigating what role Prime Mover Controls components played in the grounding. He described the control components and the valves as interrelated aspects of the MV Woods Hole.

Like many Vineyarders have done in recent weeks across social media, Marc Hanover reflected fondly Tuesday on the old service days of the MV Islander, an analog vessel considered doggedly reliable even in ugly seas. In contrast, Hanover lamented the advent of increasingly complex and sophisticated ship systems all over the world.

Commodore Lima said simplicity is the benchmark with boats: “The less moving parts, the higher the reliability.”

On April 23 Christensen described Hundested’s controllable pitch propeller system as “the world’s simplest.” While they’re only used on the Woods Hole in the Steamship Authority fleet, he said Hundested controllable pitch systems are in widespread ferry use in America and Europe, including in most Washington State ferries. He also said while certain military ships may be able to execute 180 degree propeller blade rotations, the Woods Hole propeller blades only rotate plus or minus 30 degrees or 60 degrees in total. Christenen said he will be flying to Massachusetts in a week or so to consult with the Steamship Authority.  

Editor’s note: There are multiple parts of this story that have been updated and clarified. The story has also been updated with new information.