Express 40
2007 May 5
May 2007
Class racerr
The Class 40-compliant Express 40 designed by Owen/Clarke was designed to compete in the Route du Rhum, Trasat Jaques Vabre, the Ostar and the Global Challenge. These are all singlehanded and doublehanded races. The Class 40 is a box rule that provides an "entry level" way of competing in these prestigious events. This boat was not designed for close course racing. This is an oceangoing speedster. Owen/Clarke has made a specialty of this type of design.
Box rules outline parameters, the "box" that the boat has to fit within. Often, as in the successful TP52 class, the rule constitutes a box within a box so there are limits to maximum dimensions and also limits to minimum dimensions. In this case the box describes only maximum dimensions and a minimum displacement. The idea is to provide boat-for-boat competition while leaving room for design innovation, as long as you stay within the box. This type of class is usually called a "development" class as it allows room for development. Examples of development-type classes you would be familiar with would include the current America's Cup boats, the meter boats i.e. 12-Meters, 6-Meters, etc., International 14s and the Moth. Box rules can be confining or, like the Moth class, wide open in terms of hull shapes for a fixed LOA.
The big, dinghylike hull of the Express 40 is almost all waterline, with a DWL of 39 feet, 5 inches, and a D/L of 74 and an L/B of 2.93. The displacement of this Class 40 design is just slightly over the rule minimum. The rule allows a max beam of 14 feet, 9 inches, but Clarke has chosen to stay below this. Draft is limited to 9 feet, 10 inches and there is a limit of two movable appendages. In this case there are two rudders. Water ballast is at the rule limit of 1,500 liters. There is no movable ballast other than the water and canting keels are not allowed. This general dishlike hull form is an effort to increase stability, and with it sail-carrying power. There is almost a chine showing up aft as the slablike upper section of the topsides meets the curved bottom aft. The designer wants to increase the immersed volume of the topsides aft when the boat is heeled.
The interior features the typical centerline nav station, sink and engine box you see on most boats of this type. All interior weights are designed to stay in the middle of the boat. Two berths are adjacent to the nav/galley module. There is an enclosed head forward of the main bulkhead. This design is not about cruising comfort.
The Class 40 rule limits sail area to 1,237 square feet of "true surface area." You can only carry eight sails for racing and the mast height is limited to 62 feet, 4 inches above the water surface. The E dimension is limited by making the boom stop 2 feet, 8 inches forward of the transom. If we use the rule-specified maximum sail area, and no Open 40 designer is going to leave any sail area on the drawing board, the SA/D is 41.99. You are allowed a 2-foot, 8-inch retractable bowsprit. Spreaders are swept 23.5 degrees with chainplates at the deck edge.
Twin tillers control the twin rudders. The mainsheet traveler is just aft of the tillers and the traveler has to be within 4 feet, 1 inch of the transom. All lines lead to the cockpit to facilitate short-handed sailing. The drawings show one mast-mounted winch. The foredeck is absolutely clean with only minimal toerails at the deck edge that extend all the way aft.
Carbon fiber is forbidden in this class, as are any Aramid fiber materials. Nomex or aluminum core is also prohibited. There are strict elements to this rule that are intended to keep the cost of the boat down. You can't even have a carbon rudder. The rule also sets very strict stability and safety requirements.
This will be a fast, athletic ride. But the fact that the rule is carefully written to keep the cost of these boats controlled does limit the complexity of the design and construction. In doing so the performance is restricted. Still, I would bet you this is a thrilling ride.
Class racerr
The Class 40-compliant Express 40 designed by Owen/Clarke was designed to compete in the Route du Rhum, Trasat Jaques Vabre, the Ostar and the Global Challenge. These are all singlehanded and doublehanded races. The Class 40 is a box rule that provides an "entry level" way of competing in these prestigious events. This boat was not designed for close course racing. This is an oceangoing speedster. Owen/Clarke has made a specialty of this type of design.
Box rules outline parameters, the "box" that the boat has to fit within. Often, as in the successful TP52 class, the rule constitutes a box within a box so there are limits to maximum dimensions and also limits to minimum dimensions. In this case the box describes only maximum dimensions and a minimum displacement. The idea is to provide boat-for-boat competition while leaving room for design innovation, as long as you stay within the box. This type of class is usually called a "development" class as it allows room for development. Examples of development-type classes you would be familiar with would include the current America's Cup boats, the meter boats i.e. 12-Meters, 6-Meters, etc., International 14s and the Moth. Box rules can be confining or, like the Moth class, wide open in terms of hull shapes for a fixed LOA.
The big, dinghylike hull of the Express 40 is almost all waterline, with a DWL of 39 feet, 5 inches, and a D/L of 74 and an L/B of 2.93. The displacement of this Class 40 design is just slightly over the rule minimum. The rule allows a max beam of 14 feet, 9 inches, but Clarke has chosen to stay below this. Draft is limited to 9 feet, 10 inches and there is a limit of two movable appendages. In this case there are two rudders. Water ballast is at the rule limit of 1,500 liters. There is no movable ballast other than the water and canting keels are not allowed. This general dishlike hull form is an effort to increase stability, and with it sail-carrying power. There is almost a chine showing up aft as the slablike upper section of the topsides meets the curved bottom aft. The designer wants to increase the immersed volume of the topsides aft when the boat is heeled.
The interior features the typical centerline nav station, sink and engine box you see on most boats of this type. All interior weights are designed to stay in the middle of the boat. Two berths are adjacent to the nav/galley module. There is an enclosed head forward of the main bulkhead. This design is not about cruising comfort.
The Class 40 rule limits sail area to 1,237 square feet of "true surface area." You can only carry eight sails for racing and the mast height is limited to 62 feet, 4 inches above the water surface. The E dimension is limited by making the boom stop 2 feet, 8 inches forward of the transom. If we use the rule-specified maximum sail area, and no Open 40 designer is going to leave any sail area on the drawing board, the SA/D is 41.99. You are allowed a 2-foot, 8-inch retractable bowsprit. Spreaders are swept 23.5 degrees with chainplates at the deck edge.
Twin tillers control the twin rudders. The mainsheet traveler is just aft of the tillers and the traveler has to be within 4 feet, 1 inch of the transom. All lines lead to the cockpit to facilitate short-handed sailing. The drawings show one mast-mounted winch. The foredeck is absolutely clean with only minimal toerails at the deck edge that extend all the way aft.
Carbon fiber is forbidden in this class, as are any Aramid fiber materials. Nomex or aluminum core is also prohibited. There are strict elements to this rule that are intended to keep the cost of the boat down. You can't even have a carbon rudder. The rule also sets very strict stability and safety requirements.
This will be a fast, athletic ride. But the fact that the rule is carefully written to keep the cost of these boats controlled does limit the complexity of the design and construction. In doing so the performance is restricted. Still, I would bet you this is a thrilling ride.
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