Humphree Electric Fin Stabilisers and Interceptors Retrofit to Grand Banks 47 Heritage

The Grand Banks 47 Heritage EU is a classically styled, luxurious, and highly capable long-range cruising yacht. Its extended upper deck and spacious flybridge offer exceptional comfort and protection while underway, while the expertly crafted teak interior provides a peaceful, self-contained sanctuary. Robust, refined, and elegantly timeless, it is a boat built to voyage far in comfort, confidence, and style.

This particular example arrived at Proyacht’s work sheds at the Boat Works on Queensland’s Gold Coast for a Humphree Electric Fin Stabilisers and interceptors retrofit, along with an extensive refit for its new owner. The owner had recently purchased the Grand Banks via Alexander Marine brokers, who recommended Proyacht for the work. It all lined up: The Humphree Electric Fin Stabilisers and Interceptors were already chosen; Alexander Marine knows Proyacht’s quality of craft very well; and Proyacht is the approved specialist installer of Humphree Electric Fins and Interceptors on the Gold Coast.

The owner, an experienced open-water sailor, chose the Grand Banks 47 Heritage for its long-range cruising ability, exceptional passenger comfort, and elegant design. Before taking delivery, he outlined a series of projects to meet his high standards for the vessel. A major refit was needed, including achieving a high-quality, pristine finish throughout and installing state-of-the-art Humphree stabilisation technology.

The Brief: Humphree Electric Fin Stabilisers

Humphree Electric Fin Stabilisers and Interceptors were the owner’s choice for several reasons. First and foremost, he needed a highly effective stabilisation system to minimise vessel movement at anchor and underway. Equally important is their use of 24 Volt DC power. Their efficiency, coupled with a suitable battery setup, allows the stabilisers to run overnight without an auxiliary generator, ensuring near-silent operation.

The owner had done his research. The dual advantages of highly effective stabilisation with near-silent operation at rest completely transform the boating experience for everyone on board. Sea trials on a wide range of vessels between 40 and 70 feet show that rolling motion is reduced by 70-80% while underway and 60-70% when at anchor. Additionally, a quiet boat overnight ensures all luxuries and practical features are available in a nearly silent environment.

The transformation level that Humphree Electric Fin Stabilisers offer cannot be understated for boating enthusiasts and their passengers. In terms of comfort, this system can reduce roll by at least 50% in open water, making the boating experience more enjoyable, especially for those less familiar with boating or sensitive to motion sickness. It can encourage more frequent, longer-lasting outings for husbands, wives, and families to enjoy together.

Humphree Electric Fins Stabilisers also work in harmony with Humphree Interceptors, automatically adjusting trim and supplementing stabilisation when underway. Humphree calls this ‘total stabilisation’. The result is improved stabilisation during navigation, especially in pitch control. The interceptors alter the hydrodynamic performance of any hull shape to match current conditions, thereby boosting the vessel’s cruising efficiency and fuel economy.

“Humphree’s reputation in Australia is unmatched, with the widespread use of Humphree technology across commercial fleets, highlighting its effectiveness and dependability in all conditions. Value for money is also an area where the Humphree system truly excels.” said Steve Dittmar, Director, Proyacht.

Installation by Proyacht

 Retrofitting stabilisers, whether fins or gyros, is a significant project that demands careful planning and design. A bespoke, high quality of work at this stage is crucial to the outcome in terms of performance, reliability, and safety and Proyacht is ideally suited to the task.

At 47 feet, the Grand Banks 47 Heritage is on the smaller end of the spectrum for a fins retrofit. The engine room is relatively compact, with limited space for extra hardware. A key advantage of the Humphree Electric Fin Stabiliser system is that it requires minimal inboard space, making a Humphree fins retrofit easier to perform than many alternative systems. However, careful engineering planning is necessary to reinforce the hull to handle the additional loads from the fins.

Proyacht collaborated with Grand Banks during the planning phase to gather all necessary drawings and specifications. It is fair to say that some concerns existed about whether the project could be successfully completed, largely due to past experiences with hydraulic fin systems. But barriers to a successful implementation were soon overcome.

After initial design work, a 3D replica of the Humphree Fins servo actuators was created to help refine the design approach practically. The vessel’s fuel tanks and engine were temporarily removed, and the exhaust was temporarily relocated to gain access for the systems’ installation.

Hull strengthening involved increasing the hull thickness in the specified areas to 86mm using solid fibreglass.

The Humphree system retrofit was also paired with a 24V lithium battery system upgrade to run the fins overnight and provide a greater window for generator-free operation of powered systems on board.

The Proyacht Approach to Major Refits

Proyacht has an approach that is purpose-built for complex retrofit projects on luxury boats. It is a comprehensive process that emphasises understanding their customers, their goals, the specific nuances of the boat, and then carefully planning and delivering perfect results.

“With customers, we listen, ask the right questions, communicate regularly, and make sure everyone knows what’s happening at every point of the project”, said Steve Dittmar.

“Of course, the most important aspect for safety and performance is the engineering work. It begins with the mindset that there is always a way to achieve the customer’s goals and we just figure out the best and most cost-effective approach using the highest industry standards”. Supported by persistence, expertise, and determination, Proyacht focuses on the intended result using workable solutions – from concept to completion.

Finally, quality depends on every small detail that ensures structural integrity, optimal performance, and the level of fit and finish that owners of Grand Banks and other luxury motor boats demand.

The Result

The Grand Banks 47 Heritage looks stunning and has recently been relaunched, awaiting sea trial and the arrival of her delighted owner.

The appearance, both inside and out, is just as Grand Banks would have delivered as new, with the Humphree Fins and Interceptors seamlessly and meticulously in place, ready to work their magic.

We’ll update this story once the sea trial is finished. Proyacht also has two larger 60+ foot Grand Banks boats scheduled for Humphree Fins retrofits, with one already in their work shed.

For more information, contact Steve Dittmar at Proyacht today.