The advent of modern stabilisation systems is an innovative advancement for many Riviera owners. Being able to significantly reduce the roll of a motor yacht and provide even greater comfort is opening the experience of luxury boating to the whole family, sea legs or no sea legs.
Historically reserved for ocean liners, tankers and super yachts, active stabilisation systems are now readily available for all-sized recreational motor yachts, with two technologies leading the market – gyroscopes and fins.
Riviera offers both of these equally impressive systems with a range of Seakeeper gyroscope (gyro) and Humphree fin stabilisers.
Both can be optioned on new selected Riviera yachts. It’s only the size of a motor yacht and its intended use that might persuade a Riviera owner to opt for one system or the other.
The Riviera 64 Sports Motor Yacht is among the larger Riviera motor yachts that can be optioned with either the Seakeeper gyroscope or the Humphree fin stabilisers
How stabilisation works
A boat has six degrees of freedom – these are the different directions it can move in and, while they may all contribute to motion sickness, roll is the most significant, followed by yaw (vertical rotation) and sway (side-to-side motion).
Both gyros and fins work by exerting force against the motion of a boat and have electronic sensors that determine the extent of force required. It’s the mechanics of how they create this opposing force that distinguishes the two systems.
Fin stabilisation by Humphree
Humphree carbon fibre fins are mounted lengthwise to an external flange aft on both the port and starboard sides. They work by using water flow on the fin to generate an opposing force. When a boat rolls in one direction, the fins are angled to counter this motion and the boat stabilises. The fins are designed to rotate a full 360 degrees.
The greater the speed the more water flow there is, and the more force is created to counter motion. Because their potential force increases with speed, fins are well suited to faster ocean-going motor yachts.
At zero speed, the fins require manual engagement. To combat anchor walking, the fins rotate 180 degrees to gently pull or swim away from the anchor, keeping the anchor line tensioned for minimal sway.
The Humphree stabiliser fins are fitted to the exacting standards of the manufacturer by Riviera’s master boatbuilders
Their electronic actuators are powered directly from the motor yacht’s power bank with 24V DC, which means there’s no need to run a generator while underway, again making them appropriate for longer-range cruising when fuel economy is front of mind. Humphree fins use a passive cooling system: heat is conducted away from the flange and fin as it passes through water.
The system is a compact, lightweight solution in general, with each fin weighing around 150kg and the actuators placed inside the hull requiring only 300mm of head room.
The unique flange mount of Humphree stabiliser fins is designed for easy installation both for retrofits and new builds
Notably, all Riviera motor yachts are fitted with transom interceptors (trim tabs), and these are Humphree for yachts 64 feet and over, or Volvo Penta for yachts under 64 feet. The key here is the native integration between the Humphree interceptors and fins and the ability to combat pitch, roll and yaw simultaneously, thus optimising the running trim and list angle while underway.
Installation and maintenance are convenient. The unique flange mount has been designed for easy installation both for retrofits and new builds. It even allows for the removal of the fin under water. And while additional external appendages may make some skippers nervous, Humphree fins are engineered to break away on strike, taking the fin out without affecting the boat.
Humphree fins are available on all Riviera motor yachts 68 feet and larger, and on 64-foot yachts by request.
Gyroscopic force by Seakeeper
Seakeeper is a completely internal and computer-controlled system. It’s a modern technology that also uses universal forces of nature.
Encapsulated in a vacuum sphere is a flywheel that spins continuously at speeds of up to 9,750 RPM. This spinning creates a gyroscopic effect that maintains a steady axis – imagine a spinning toy top and its vertical axis.
When a boat rolls, the Seakeeper’s sensors are activated and the sphere is tilted fore or aft, referred to as gyroscopic precession. This creates gyroscopic torque – or more precisely, angular momentum – which exerts force to port or starboard to counteract the roll and stabilise the boat. The greater the precession, the greater the stabilising force.
Inside the Seakeeper gyroscope with its flywheel that spins at speeds of up to 9,750 RPM within a vacuum sphere
Crucially, a Seakeeper is completely effective at zero speed and this makes it ideal for families who love to spend time at anchor. It’s also a relief to skippers whose cruising grounds are shallow as the Seakeeper has no external appendages, reducing the risk of strike or entanglement.
Being sealed in a vacuum allows the flywheel to spin faster while reducing its weight and energy requirements, although it does require 240V power and therefore a generator to operate.
The Seakeeper gyroscope system is situated aft in the engine room for minimal noise
Also sealed within are its bearings and the motor, completely isolating these critical components from the marine environment. An effective cooling system removes heat from the enclosure and disperses it through a combination of seawater and glycol.
A Seakeeper, for example the SK16 that is crafted for 60 to 69-foot motor yachts, weighs around a tonne. It’s a neat unit that can be retrofitted to any sized Riviera, and is situated aft in the engine room for minimal noise.
Through these stabilisation systems available on select motor yachts, Riviera has provided greater versatility and reassurance for owners planning boating escapes in a range of on-water conditions.
