NOW SOLD – 2021 Ultimate Boats X-Class 11m RIB

Grabau International is delighted to confirm its successful sale of the 2021 Ultimate Boats X-Class 11m RIB ‘STORMBIRD’.

Using technology from the Valkyrie supersonic bomber of the 1960, the Ultimate Boats, John Moxham designed a hull that differs from all that have gone before. Exploiting a design principle where water is entrapped below the hull, rather than thrown out to the sides, the boat rides on a cushion of entrapped water. This cushion provides hydraulic lift, giving a much flatter trim than a normal RIB, as well as offering blistering performance, unrivalled handling and surprisingly smooth ride.

The Ultimate Boats X-Class is the Rolls Royce offering from a builder normally focused on commercial craft. Built for a discerning owner STORM BIRD has been fitted out to the highest standard with a packed inventory including highlights such as:

• Twin Suzuki DF350 Petrol outboard engines
• Single station electro-hydraulic steering system
• Zipwake Interceptor Dynamic Trim Control System
• Exalto digital windscreen wiper control system
• 2x Raymarine Axiom PRO 16” MFD displays, fully configurable
• Raymarine Quantum digital radar scanner
• Raymarine CHIRP fishfinder transducer
• Raymarine CAM300 Eyeball Day and Night camera, displaying on Axiom MFD
• Raymarine RAY63 VHF
• Raymarine AIS700
• Fusion RA770 touchscreen marine stereo system with Airplay 2 software and Wi-Fi streaming
• Fusion Signature Series 3i speakers with LED backlighting

PRESS REVIEW:

The name may sound rather hubristic but thanks to a revolutionary new hull design it may not be far from the truth. Simon Everett drives the Ultimate Boats X-Class.

The 1950s and 1960s were a time of great innovation, driven by the race to the moon and the Cold War, which, believe it or not, is where the Ultimate Boat Company’s new range of rugged high-performance RIBs has its roots.

The Ultimate Boats may be a relatively young Scottish-based yard but its talented team of designers includes a highly experienced naval architect by the name of John Moxham.

Back in the 1960s Moxham worked on the XB70 Valkyrie, a high-altitude supersonic bomber capable of flying at Mach3.

It flew higher and faster than any fighter plane of its era. The key to its performance was specially shaped wing tips that trapped the air to give the increased lift and stability required to keep it flying in the thin atmosphere at 70,000ft.

The hull of the Ultimate Boats X-Class uses the very same principle. Instead of throwing the water out sideways, it rides on a cushion of entrapped water held there by Moxham’s specially shaped ‘retaining rails’.

It is counter-intuitive but the compressed water also acts like a shock absorber, helping to soften the ride. In Moxham’s own words: “When a boat is moving at speed, tonnes of water are moved to either side of the boat in the form of wash. Viewed from above, this wash forms a V shape.

“The new hull has vertical retainer rails which prevent the wash moving away from the hull. As the water is unable to move sideways or downwards a hydraulic force is formed which lifts the boat upwards, hence the principle of hydraulic lift.”

Another noticeable side effect is that the X-Class trims much flatter than most planing craft, 2-3 degrees instead of the usual 5 or 6 degrees, due to much of that enhanced lift being at the stern.

The compressed water beneath the hull also has another benefit, giving more bite to the props even during extreme turns, resulting in virtually no detectable side slip or cavitation and minimal loss of speed.

For a boat aimed primarily at the commercial and military markets, its main focus is on comfort, stability and payload capacity rather than maximum speed. But it’s no slouch either. There is virtually no bow rise when accelerating, it simply slides up onto the plane without any discernible hump and can hold that planing aspect at just 11 knots.

The special chines, or Moxham retaining rails, are more than simple reversed chines. Starting fine at the unusually high stem to provide bow lift during a plunge, they increase in size towards the stern where vertical dams entrap and compress the water.

Coupled with a deep 25-degree deadrise angle at the transom, it helps explain its remarkable ride and handling.

I tested a prototype 7.5m version of the X-Class in a 4-5ft swell with white tops and, despite testing hundreds of RIBs over 30 years in the industry, I can honestly say it left my eyes wide open in amazement. This much larger 11.0m version is even more capable.

The strength and rigidity that Ultimate Boats engineer into each craft doubtless helps that impression of indestructibility. There are no fewer than six hefty resin impregnated foam longitudinals with similarly constructed cross beams every metre helping to deliver a very robust hull and a pleasantly quiet ride.

The owner of this boat specified a Hypalon covering that looks like an inflatable tube but it’s actually a rigid polyurethane collar that can be colour matched to the hull. The rigid collar has several benefits; it uses less internal space than an inflatable one, it cannot deflate and it is harder wearing.

This boat was commissioned for transporting guests across from the mainland to the isle of Tiree off the West Coast of Scotland, hence the Scotseat suspension units for Ultimate Boats’ own bucket seats to ensure a comfortable ride even when things cut up rough, as they do quite regularly up there!

The wheelhouse has a hinged screen that can be opened in fine weather or dogged shut for cooler, inclement days. There is also a canopy system aft for weather-proofing the entire cockpit. In essence it is a high-speed water taxi with a few nods to hospitality for day trips, such as the fridge and space for a galley fitment.

The high bow and freeboard provide seakeeping commensurate with the conditions. Enclosed side decks give a safe walkway forward o the deep bow cockpit with its 80cm of internal freeboard. Three steps up to the foredeck are set into the chain locker hatch where the anchor is held in a dedicated rack.

The twin 350hp Suzuki outboards are steered electronically and linked to an Optimus 360 joystick control system for close quarters manoeuvring and holding station using a GPS lock. Moving an 11m RIB sideways, without bow thrusters, is a very clever piece of vector thrust control but it does seem to work.

The props are still being tweaked for optimum performance but during our test they pulled to 5700rpm giving a top speed of 45.5 knots. There will doubtless be a few more knots to come when the engines are able to reach maximum revs.

Motor Boat & Yachting – October 2021

We wish her new owners fair winds and following seas.

For those that missed out, Grabau International has several other similar yachts available for sale, including:

Invictus TT460 – full details here

Red Sky 29 Antibes – full details here

Golden Cut 28 G – full details here

Do you have a yacht like this to sell? Grabau International is always looking for new high-quality cruising yacht listings in the UK and internationally. For further information about our tailored brokerage services, please look here