Drag reduction
When it comes to analysing the drag reduction benefits of elliptical rigging, Duval says the windward- facing rigging isn’t the main issue. ‘One of the concerns about an elliptical shape is that people think it presents a wide profile to the wind on the windward side of the boat. However, a great amount of drag is coming from the leeward side too, in the slot between the jib and the main, because you've got this massive wind tunnel. That's where the drag comes from. The air is accelerated through the slot by at least 50 per cent, so despite the angle of airflow being narrower, this increased air speed means that the drag generated on the leeward side shouldn’t be disregarded. Therefore a good balance between both sides is required to reduce drag forces. ‘AEROsix brings benefits in both of these scenarios. Its extended ellipse leads to minimum drag in high speed and low wind angle leeward side. Whilst the rough surface also provides exceptional aerodynamic performance for the range of angles of airflow on the windward side. This makes AEROsix the best solution to date. We’re going to be running some VPP analysis to put some hard figures on just how much wind reduction we’re looking at.’
Spreader attachments
Spreader attachments and terminals for AEROsix have been designed to the same specification as ECsix, making it straightforward for existing ECsix rigs to be swapped out for AEROsix. ‘Some people have been concerned about the robustness of the plate,’ says Duval. ‘However, the plates are engineered to be able to resist impacts and to achieve this robustness we developed a special resin and placed special carbon reinforcements in the required places. The key thing is that each plate goes from the top of each diagonal to the bottom of the cable, so there are no plate joins along the cable. When we manufacture the cables, we ensure that the strain on every single element of the rigging is the same. So when the cable is working in tension at working load, the strain on the rods and on the plates is identical - everything works together. The tension is spread equally across all elements of the rigging. The combination of all those points means that AEROsix will stay as robust as the ECsix product.’
The bonding surface for the cone
Duval says the cone has been designed to have the same break strength as ECsix. ‘For our existing
Above: these three images show the results of CFD analysis that backs up Future Fibresʼ VPP findings. Top: the velocity
profile around a round rigging section
(independent of the angle of attack). Middle: the velocity
profile around a 2:1 elliptical rigging section at a 20º angle of attack. Lower: the velocity
profile around a 2.7:1 elliptical rigging section at a 20º angle of attack
customers it’s important to be able to easily replace their ECsix rigging with AEROsix if they choose to do so. This is what happened with Magic Carpet because they've got the two setups, they've got both EC6 six and AEROsix. We have therefore designed the cone so that the compressive pressure on the cone is operating at the same level.’
Coilability and ease of transportation
One of the major limitations of solid carbon rod rigging is the near impossibility of being able to coil it. This makes transportation of rigging very difficult. Multi-strand rigging on the other hand is easy to coil – and AEROsix too can be coiled, according to Duval. ‘With ECsix we have two types of carbon rods, 1mm and 2mm diameter. The 2mm rods require a bigger coiling radius when you coil them up for transport. With AEROsix, we’re looking at a coiling radius close to the 2mm ECsix because of the thickness of the blades within the AEROsix structure.’
While it’s still early days for AEROsix in the real world, all the signs are very encouraging from the early adopters, not least the Wallycento Magic Carpet 3, the IRC52s Beau Geste and Ichi Ban, and the Gunboat 66 Mach Schnell. ‘AEROsix has met all our expectations,’ says Gallican. ‘It does what it says on the tin. It was straightforward to set up on the boat, and it sets up really well. It all went
together pretty nicely and we had very good backup from Future Fibres.’
www.futurefibres.com
Greg Monks, owner’s representative, 60m performance cruiser
Greg Monks is leading a new-build project for a 60m performance sailboat, which is in construction at Royal Huisman.
Chiming with Juan K and Danny Gallichan’s enthusiasm about minimising vibration, Monks sees this as a major selling point for AEROsix. ‘For superyacht captains and anyone who knows the industry, you don't want resonance going through the boat, you don't want owners to be upset by having noisy rigging. It’s an important comfort and performance factor, to be able to get rid of those vibration and resonance issues.’
Monks has every confidence that AEROsix will deliver, based on more than eight years’ experience with ECsix. ‘We’ve sailed around the world, on occasion in very severe conditions and we’ve found ECsix to be superb in terms of reliability. From the service side, we were in New Zealand when we did our five- year service period. Packaging it up, sending it away and having it serviced in Spain was easy. That ease of transportation is important to us and it’s one of the appealing factors of AEROsix.’
SEAHORSE 81
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