Magic Carpet 3 & the 100 footers

written by François Chevalier. Translated from Jacques Taglang's blog.

As soon as she hit the water, Magic Carpet 3 took a flying start. Her designer delivered a real winner thanks to her very special lines. Whether in light airs or in a sustained breeze, she has outclassed her competitors.

sailplan, body plan, sheer plan, half-breadth plan and deck layout of Magic Carpet 3, courtesy © François Chevalier

Naval architects John Reichel & Jim Pugh had exhaustively developed the narrow yacht with Wild Oats XI, which, throughout her career thus far, has received all possible appendages, including a canard in her original CBTF configuration. By raising the "progressive" hard chine of the new Magic Carpet 3, her designers have significantly reduced the waterline beam when the yacht is level, thus keeping the wetted surface to a minimum. As the Wally class rule forbids canting keels, Reichel/Pugh opted for a relatively large displacement, with a large quantity of the overall weight placed in the finkeel ballast. When the yacht is heeling, the hull sails on a flat surface as well as the hard chine (which provides lateral resistance) and starts to plane at the slightest of breezes. The same hull shapes can also be found on the latest generation of the Open 40 class yachts, which have proved to be more complex to optimise than their predecessors.

Magic Carpet 3 (WallyCento class rule)
Designer: Reichel/Pugh
Builder: Wally, Ancona (ITA)
Build material: Carbonfiber
Length of Hull: 30.48m (100ft)
Load Waterline Length: 29.49m
Beam: 7.19m
Waterline beam: 4.70m
Draught: 6.20m / 4.50m
Displacement: 50 tonnes
Lifting keel
Air draught: 45.00m

sailplan, body plan, sheer plan, half-breadth plan and deck layout of Wild Oats XI in her 2012 configuration, courtesy © François Chevalier

Wild Oats XI is a much narrower yacht than Magic Carpet 3 with a waterline beam of just 4.10m. Her lines features a slightly rounded bilge, flaring topsides, and a moulded depth positioned forward of the keel fin. When heeling, the waterline is as long as the full length of the yacht, the wetted surface is reduced, but the flaring topsides do not provide lateral resistance like more recent yachts with chine-bilged hulls like Magic Carpet 3 or Rambler 100 (Juan Kouyoumdjian design, formerly Speedboat).

Wild Oats XI
Designer: Reichel/Pugh
Builder: McConaghy's, Sydney (AUS)
Date of launch: December 2nd, 2005
Length of Hull: 30.48m (100ft)
Length Overall: 33.83m
Load Waterline Length: 29.70m
Beam: 5.40m
Waterline beam: 4.10m
Mast length: 44.10m
Draught: 5.50m
Weight: 32 tonnes
Ballast: 14 tonnes
Sail area, mainsail: 382m²
Sail area, jib: 228m²
Sail area, genoa: 505m²
Sail area, spinnaker: 880m² 

sailplan, body plan, sheer plan, half-breadth plan and deck layout of Rambler 100 in her 2011 configuration, courtesy © François Chevalier

The shape of Rambler 100 (formerly Speedboat, now Perpetual Loyal 100) is similar to that of a motor boat. Her hull lines are very sleek and it is difficult to read the shape of her aftersections. Because of this, her horizontal sections (which are parallel to the waterline) all stop abruptly at the transom. Generally, the beamier the vessel, the larger the developed surface of the hull and deck, incurring extra weight to the yacht. But the closer the overhead shape of the deck is to a triangle, the lesser this developed surface actually affects the hull weight and Rambler 100 is very close to a triangle. Half the yacht's weight is located in the canting keel, which is swung to windward. When the wind strengthens, 8 cubic metres of water are pumped to the windward liquid ballast tank, which provides Rambler 100 with a huge righting moment.

Rambler 100 (formerly Speedboat, now Perpetual Loyal)
Designer: Juan Kouyoumdjian

Builder: Cookson Boats, Auckland (NZ)
Date of launch: April 17th, 2008

Length of Hull: 29.99m
Load Waterline Length: 29.99m

Beam: 7.00m

Waterline beam: 4.95m
Draught: 5.70m

Air draught: 46.50m

Bowsprit: 3.60m
Displacement: 30.6 tonnes

Ballast: 15 tonnes

Liquid ballast tanks: 8,000 litres
Sail area, upwind: 630m²
Sail area, downwind: 1,340m²

sailplan, body plan, sheer plan, half-breadth plan and deck layout of François Chevalier's Maxi Scow proposal

My 100ft Maxi Scow proposal features hull lines which are close to those of a surf board. This increases the drag in the light airs compared with a narrow yacht like Wild Oats XI, but gives her greater ability to plane in the puffs. When heeling, the wetted surface is reduced and the angle between the heading and the centerline of the yacht is smaller than on any other maxiyacht. Furthermore, her shape stability is also greater.

Maxi Scow
Designer: François Chevalier YD
Proposed builder: either Multiplast (France), Green Marine (UK) or Cookson Boats (NZ)
Length of Hull: 30.48m (100ft)
Load Waterline Length: 26.70m
Beam: 7.20m
Waterline beam: 5.40m
Draught: 5.60m
Displacement: 38 tonnes
Canting keel
Air draught: 46.00m
Sail area, mainsail + jib: 628m²
Sail area, mainsail + gennaker: 1,110m²

A stand off between these four Maxi yachts in a New-York Bermuda, a Fastnet or Sydney-Hobart would be an educative and unforgettable spectacle.

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