Steady as She Goes

Retrofitting a gyroscopic stabilizer improves a classic Trumpy.

January 26, 2011

Steady as She Goes

They say every boat is a compromise. Speedy boats suck fuel. Big boats need big slips. Slow boats aren’t made for weekend warriors. Every boat has trade-offs built into them. And if you want to host family and friends on a classic wooden Trumpy houseboat motoryacht with a shallow draft, you’re going to have to put up with a little rolling.

At least, that’s what Ted Conklin thought. As owner of America, a 75-foot Trumpy motoryacht built in 1965, Conklin realized the roll could be enough to put people off. “We charter her rather regularly and I use her personally,” Conklin says. “Her home port is Sag Harbor, New York, and when we go into the [Long Island] Sound — or up to Newport — we very often will have a beam sea, and it can, under certain circumstances, be a little bit uncomfortable.” Consider also that a boat like America, which also hosts events and dinner cruises, will draw guests who don’t have their sea legs.

Funny thing is, America’s stability was an issue before, so much so that she had fin stabilizers installed at some point in her history. A previous owner decided to remove them when he heard about another Trumpy with fin stabilizers that came to grief in the Intracoastal Waterway. One of the fins hit an obstruction and tore a 4-by-6-foot hole in the wooden bottom, sinking the boat.


“They’re vulnerable [fins] and you get into these older boats,” says Jim Moores of Moores Marine Center, a Beaufort, North Carolina-based yard that specializes in repair and upkeep of classic wooden yachts ( “A lot of times fin stabilizers are improperly installed. We took a set off of an 80-foot Trumpy and it had pried all the planking off the side of the hull.”

Moores and his crew have worked on many Trumpys, and Moores Marine is the service yard of record for America through five owners now. While Moores clearly loves these boats, he’s aware of their foibles. “These old boats are very long, and they don’t have a lot of buoyancy forward,” Moores says. “It’s part of the design. The reason for that is that they’re a cross between piercing technology and planing technology. They run through the water really nicely, but one of the problems with being narrow, like America, is you get into the right sea and the furniture will move from one side of the cabin to the other.”

Conklin wanted some form of stabilization, and he turned to Moores for advice. Moores had his own requirement: “I want stabilization that, if the boat goes through a light grounding, it’s not going to poke a hole in the bottom.”


Enter gyroscopic stabilization from Seakeeper. Simply put, this self-contained unit is mounted inside the hull and uses the energy from a rapidly spinning gyroscope to dampen the roll. No part of the Seakeeper M7000A protrudes from the hull. “We spin our flywheel inside a vacuum,” says Brook Stevens, inside sales coordinator for Seakeeper. “With no air friction we’re able to spin at much higher rpm, consuming a lot less power. It takes only 3 kW to spool the unit up to full speed and 1½ to 2 kW operating power.”

How does it work? If you recall playing with a toy gyroscope, the flywheel turns and maintains its orientation thanks to angular momentum. Since the mass of the flywheel and the rate it rotates determine the force generated, a heavy flywheel spinning very fast will be a powerful tool. Seakeeper uses hydraulics on its 1,000-pound M7000A to bring those forces into play to dampen the movement of the boat. “We actively control the rate at which it precesses to maximize the roll reduction throughout the whole roll period of the boat versus [using] a passive dampening system,” Stevens says. “If you look at our unit you see basically a hydraulic system on the side. We’re not driving the unit fore and aft, but we’re just controlling the rate at which it precesses to maximize the roll reduction.” Precessing means the gyroscope moves with its momentum, compensating for the motion of the hull.

It sounds like a solution. But on a yacht like America, one would expect the unit to exert forces on the structure far different from those intended by her designer and builder. “Trumpy houseboats of that era were built real light,” says Nathan Smith, project manager at Moores Marine and a master carpenter specializing in structural marine carpentry. “And they weren’t meant to have that kind of torque put on them.” The team at Moores Marine looked closely at the structure of America around the installation site.


“We’re having to beef up the area that this thing is going into,” Smith says. “We took out the sawn ribs that were in the boat, and we’re putting laminated ribs into it. So we’re giving it quite a bit more strength in there. There’s laminated floor timbers in there also, which gives it more strength. Before, they had plywood knees where the chine was, where it punctures the ribs. We’re putting oak knees in there now to give it more strength in that area. We’re actually laminating the oak together as well.” Smith and his team also cut the floor timbers down to accommodate the precession of the ball. The installation of the $84,000 unit took six weeks.

Seakeeper suggests spreading the forces out. “The standard mounting is epoxied in place so you’re able to spread that load across the entire saddle beam and the entire surface area of the U-shaped channel that runs on either side of the gyro,” says Pete Blanchet, supply chain and service manager for Seakeeper. “So you’re taking a lot of load but are able to spread it across the larger surface area, and that helps dissipate the force.”

“We’ve been able to get more strength using today’s adhesives,” Stevens says. “We don’t want to worry about bolts after time wearing and pulling through.” Hardware would merely focus the forces on the connection points, while a broader adhesive area spreads them out.


The unit is relatively compact, but Seakeeper wanted to make sure it’s also a good neighbor, since retrofitting may mean placing it near the accommodations spaces. It needs to be relatively cool. “Our unit is liquid-cooled where others are air-cooled,” Stevens says. “It can get into some tighter spaces without excessive ventilation systems.”

Of course, quiet operation is a must. “We’re checking every gyro for excessive vibration before it’s shipped,” Blanchet says. “If you’re in a boat that’s operating a genset, the gyro is going to be hidden in the background noise.” The gyro operates at 70 decibels.

Because of space constraints, the gyro on America was placed directly beneath a berth in a guest stateroom. “I forgot that we had it running, and I asked some guests, ‘How’d you sleep?’” Conklin says. “And they said, ‘It was wonderful; there was this beautiful, very slight hum and it helped us go to sleep.’ You can’t really hear it at all.”

Conklin seems happy with the installation, and the result. “It’s all about the pleasure of being on a boat, and if you’re waked in a harbor it’s no fun,” he says. “It solves that problem, and if you’re at a dock and it’s a bit of a blow, you can have a comfortable dinner or evening on the boat at the dock because the boat is absolutely flat. And if you’re uncomfortable in a three-foot beam sea, it acts like you’re in a one-foot beam sea. It’s a winner.”

That Certain Feeling
Here’s how America’s stabilizer feels in action.

How would you describe the motion of a boat? Here’s what Jim Moores of Moores Marine center had to say about the stabilized hull motion of America. “The best way to explain this is that, if the boat is rocking back and forth, the stabilizers say no…no…no. it tightens and tightens and tightens and tightens,” he says. “so what happens is, on the first roll it rolls; then, as [the gyro] starts precessing back and forth, it’s like check…mate…check…mate…check…mate. That’s a very cool feeling. If you’re standing on the deck, it almost feels like the boat lifts out of the water.”

“We were on the 3rd of July up in Sag Harbor, and the captain and I were running the boat along, and Ted had a whole party of about 12 people on board. And the captain and I are just watching everybody, and the boat has all this white carpeting and everyone’s drinking red wine,” Moores says. “I guess this is the real test here. Nothing slid; nothing dropped.”

“The other nice thing is that when we were in Newport Harbor we left it on,” Moores says. “There were a couple of good-size wakes, and she just sits right there and she works at zero speed. That’s something the fins don’t do well. I mean they say that they do, but they kind of swing back and forth and the boat will go forward. The whole idea of being able to sit out on the hook … and the gyro is quiet, it’s as quiet as a Cruisair air-conditioner.”


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