New gyro stabilisers that won't rock the boat

New gyros were installed under the aft cockpit to level the ride without adding to drag.
Martin Flory
You spend all this money refitting a superyacht and it still rolls like a drunken sailor… it’s enough to make you sick. Literally.

In the case of MY Banyan, a 31-metre Palmer Johnson cruiser that was built in 1980 but extended, repowered and refurbished in 2009, help was at hand in the form of twin M7000A Seakeeper gyros.

The vessel can now travel in bigger seas to remote anchorages for her owner and charter guests, and is more stable at anchor.

The owner was very conscious of ambient noise onboard so the new system needed to be quiet. Banyan's twin 33 kW gensets serve well but amperage draw needed to be conservative.

'Hydrodynamics were a big issue for Captain Andrew Grego, having gone to the trouble of extending the hull by 4.3 metres to gain speed and fuel efficiency. With 875hp C18 CAT turbo diesel pushing top speeds of 22 knots, and 14.5 knots at cruise, he didn't want anything below the waterline that could reduce the efficiency or alter the boat's handling.

'Seakeeper required just a simple wire run. It's almost no amperage draw on the boat at all when the gyros are spooled up,' he said. 'Everything else on Banyan was first-rate technology. We thought the Seakeeper gyros provided more modern technology than a fin system.'

The two Seakeeper M7000A gyros combined produce an impressive 14,000 newton meter seconds of angular momentum, with each using a flywheel operating inside a vacuum. This aerospace-inspired technology creates powerful righting forces, whether a craft is underway, at low speed or at anchor.

One nagging problem from Banyan's extension was that the boat had more buoyancy aft than desired. Installing the Seakeeper units under the aft cockpit created an additional value by helping level the yacht.

'After a run to the British Virgin Islands it was obvious the gyros definitely make a difference,' Capt Grego said. 'At anchor, the system dampens roll by 73%, which is pretty considerable, and cruised 57 hours straight in 2.7 to 3.6 metre swells the entire way, and it was comfortable.

'I definitely see a trend toward more vessels, whether new builds or retrofits, opting for zero-speed stabilisation.'

Accommodating up to eight guests, Banyan cruises the Bahamas, Caribbean, U.S. East Coast, Newfoundland and Nova Scotia. The completely refurbished yacht includes a new cockpit, lazarette storage area and BBQ.

It offers an extensive array of electronics and entertainment in a luxurious setting, as well as snorkeling and fishing gear, Vespas and water toys.

Yacht Banyan website