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The Volvo Ocean 70 Explained

Volvo Ocean Race organizers put the design parameters in layman’s terms

September 8, 2003
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Today, Volvo Ocean Race organizers released details of the new Volvo Ocean 70 Rule and a lengthy Q&A; explanation.

Q – Why a new boat?

A — Since its inception in 1993 the boats that have been produced under the Volvo 60 rule have been developed and refined to the limits. With each event the boats have evolved rapidly and proved to be quicker than their predecessors. The sailors and designers agree that after several design cycles and after three events spanning nine years, technology has progressed such that faster boats would be possible if the rules were relaxed. Starting again from afresh rather than trying to make an existing rule fit a new breed of boats was believed to be the logical step.

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Q — Why make the boats any bigger?

A – Faster boats are generally more comfortable to sail and live aboard. Bigger boats are usually faster too. A small increase in length means a proportional increase by the square in sail area and by the cube when it comes to volume. This means that the power from the rig increases rapidly with length, as does the volume available to create more comfortable living space.

Farr Yacht Design’s early vision of the new VO70. Courtesy Farr Yacht Design/Volvo Ocean Race

Q — So how can these bigger boats be sailed by fewer crew?

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A — Even in the short time since the last race, new and proven technology has meant that designers and builders can create lighter boats, while at the same time increasing the power available. Sail furling systems are a good example and will be allowed aboard the new boats. Being able to roll away a sail temporarily is far less physically demanding on the crew than the conventional system of lowering and bagging a sail each time.

Q — Why are the boats 70.5ft (21.5m) long?

A — We studied cost vs size vs performance comparisons and 21.5m came out on top.

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Q — What are the main factors that govern the new boats under the new rule?

A — In broad terms the main influencing factors are maximum overall length, a minimum and maximum beam, maximum draft, a displacement of between 12.5 and 14 tonnes and a minimum bulb weight of 4.5 tonnes?

Q — How will the new boats compare with the Volvo 60s?

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A — At 21.5m the new boats will be 2m longer but as much as 1000kg lighter. The Volvo Open 70 will carry up to 60 percent more sail area downwind in the spinnaker alone. The mast will be 4m taller, the boom a metre longer and the mainsail 28 per cent bigger than on the 60s.

Q — How much quicker will the new boats be?

A — Expert predictions suggest that the new boats would be 21 days quicker around the world than the Volvo 60s if they were to sail the same course. An improvement of 18 percent.

Q — How fast will the Volvo Open 70’s have to travel to achieve this?

A — The current 24-hour record set by Illbruck in the last race stands at 484 miles. Most of the Volvo Open 70 boats in the fleet should be able to beat this and achieve 500-mile days. To do this they will need to maintain an average speed of just under 21 knots. This will mean peak boat speeds of around 35 knots.

Q — Who set the limits for the new rule?

A — The Royal Ocean Racing Club’s Rating Office were contracted to produce the detail of the rule but the overall concepts were drawn from a committee including some of the most experienced designers and technicians around the world. These included designers, Farr Yacht Design, Rob Humphreys, Jim Pugh, Juan Kouyoumdjian, Hugh Welbourne, Rolf Vrolijk and the Wolfson Unit in Southampton.

Q — Apart from increasing the length and the sail area of the new boats, are there other changes in the rule that will contribute to the increase in performance?

A — The new boats will be more powerful because they will be proportionally lighter. Non-metallic rigging is now allowed for the standing rigging, (the stays that support the mast) which could save as much as 100kg in weight aloft. Canting keels are now allowed and provide a more efficient means of reducing the heeling. Sailing the boat more upright develops more power.

Q — What is a canting keel and why is it more efficient than water ballast?

A — Using hydraulic rams mounted inside the boat, a canting keel can be swung to one side to reduce the heeling of the boat when under sail. The water ballast systems as used on the former Volvo 60s meant that up to 2.5 tonnes of water had to be pumped up onto the high side of the boat to help reduce the heeling. With the water on board the boat was then up to 2.5 tonnes heavier and therefore slower.

Canting keel systems increase performance without the boat having to put on weight. The angle that the keels can be swung to one side is limited for safety reasons to 40 degrees either side of the centre line.

Q — Why limit the angle that the keels can be canted?

A — The restriction is to do with the balance between safety, performance and cost issues. Greater canting angles increase the load in the structure, increase the costs of the system and can give rise to several safety concerns.

Q — Do canting keels provide any further advantages?

A — Pumping water ballast from side to side required plenty of electrical power for the high speed water pumps aboard the Volvo 60s. The hydraulic rams to power the canting keels aboard the new 70s will require less power which in turn means that less fuel will need to be carried. Less fuel means less weight and better potential performance.

Q — Is any water ballast carried aboard the new boats?

A — Water ballast may be used to change the fore and aft trim of the boat in order to make the Volvo Open 70s easier to handle downwind. Up to 1200ltrs of water will be allowed in a tank mounted on the boat’s centreline. Pumps are not allowed and the tanks have to be filled using a scoop mounted under the boat.

Q — What is a self-righting test and why do yachts have to carry out one?

A — Each boat will have to prove that it can be righted from upside down if necessary. This will be achieved by turning the boat upside down in a safe location. A number of crew who will be inside the upturned boat will have to demonstrate that by canting the keel from inside, the boat will right itself.

Q — What other changes have been made to the underwater details of the new boats?

A — The Volvo Open 70s will be allowed any number of foils or rudders in any position, so long as they only have one axis of movement. Configurations such as twin rudders, forward rudders, canards and dagger boards will be allowed.

Q — What are canards and dagger boards and why would they be necessary?

A — When the keel is canted to one side to help reduce the heeling of the boat, the keel foil can no longer stop the boat from sliding sideways. A canard or dagger board is a retractable foil that looks like a keel but without the ballast bulb at the bottom. The additional foil acts as if it was the foil of the keel and prevents the boat from sliding sideways.

A canard is a single foil mounted on the centreline of the boat usually forward of the mast. Dagger boards come in pairs and are usually fitted either side of the centreline, in the vicinity of the mast and where only the leeward foil is used at any given time.

Q — Why would a designer choose to go for a twin rudder system?

A — Twin rudders offer several potential advantages. Each of the pair of twin rudders usually draws less than a conventional single rudder. When the boat is heeled only one rudder is in the water, reducing drag. The rudder’s position towards the lowest part of the hull when heeled and the fact that the rudder is aligned to be closer to the vertical plane when the boat is heeled makes the foil more efficient.

Having two rudders is also considered by some designers to be safer in the event of a collision as it is less likely that both rudders will be damaged.

Q — Will the new 70s have engines and propulsion units?

A — Yes, boats will have to have engines and prop systems with 120ltrs of fuel for emergencies in order to allow them to motor to a safer location, be it a harbour or a major shipping lane.

Boats will be allowed to have retractable prop shafts, which will reduce drag and increase performance. With props tucked away when sailing boats will have more efficient props for motoring than the low drag small bladed types that have been preferred in the past when the props and shafts were not allowed to be retractable.

Q — How much fuel will a Volvo Open 70 carry and what is it used for?

A — The minimum fuel tank size is 230ltrs. The fuel is used mainly to generate power for the navigation and instrument systems, lights, keel movement, communications, the water maker and the media equipment.

Q — What will the new hulls be constructed from?

A — Carbon fibre will be allowed in the construction of the hull and deck. Previously carbon was prohibited and the previous VO60s were constructed from aramid and glass fibre sandwich laminates. The new laminates will also be sandwich construction using a foam and/or Nomex core.

Q — What will a Volvo Open 70 weigh?

A — The hull, deck and rig will weigh approximately 6,800kg. The keel fin and bulb will weigh 5,700Kg making an all up total weight of 12,500kg.

Q — How many sails will each team be allowed?

A — Sail wardrobes have been reduced in order to help reduce campaign costs. Just 24 sails are allowed in total, 11 for any given leg, or in-port race, are allowed aboard each boat not including mandatory storm sails. VO60s were allowed 18 sails per leg last time. However the rules on modifying sails during the event has been relaxed to take account of the smaller total sail wardrobe.

Q — With inshore races now forming part of the overall event, will teams have inshore and offshore suits of sails?

A — Unlikely as the total number of sails allowed is not sufficient to provide two full ranges of sails. Deciding on where to place the emphasis in the sail wardrobe will be an important task for the teams’ sail makers.

Q — How does the mast differ from that of the VO60s?

A — Apart from being taller the new Volvo Open 70 masts will be very similar in their overall concept and construction. Masts will be made from carbon fibre and are expected to use similar sections to those used aboard America’s Cup boats. The proportions of the new rigs and the loads that will be generated were aimed at levels that would allow America’s Cup spar makers to utilise the moulds already available for mast sections.

Q — Why do boats use halyard locks in the masts?

A — Locking a halyard at the top of the sail reduces the compression in the mast and the stretch in the halyard. Less compression makes the masts more stable in extreme conditions as they are less likely to buckle under load.

Q — Will the interiors of the boats be different?

A — Apart from more space for less crew, the new rules specify minimum bunk sizes as well as a minimum of 10 individual berths. Fewer crew means more emphasis on crew comfort and safety below decks. Galleys will be better positioned and equipped. A navigation station separate from the media station will be required under the new rules and the toilet facilities will be improved.

Q — Will spectators and those following the race see any differences in the footage that comes back from the boats?

A — Each boat will have seven fixed cameras on board and teams will have to supply 20 mins/week of footage. Previously this was 8mins/week. Better editing facilities will allow crews to control the cameras and even edit the footage from a portable machine on the weather rail!

There will be a red button on deck that can auto-capture on video dramatic moments as they happen. From triumphs to disasters, all the crew has to do is hit the red button and the video system takes over automatically and records the event.

Q — Will the racing be broadcast live?

A — The satellite transmission rates in the Southern hemisphere are in the order of 64kbs. Standard television transmission rates are 270mbs. Low transmission rates mean that it is only possible to stream low resolution images live. Nevertheless, on board video compression software will allow edited highlights to be beamed back from the boats.

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