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42' and 50' Cruising Sailboat DesignsSuper-shallow, super-fast sailboat hull design |
This design has been assigned US Patent #7752986 B2
Below is an ad I ran In latitude 38 magazine.
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The above shown super shallow, super fast, radical hull at DWL 50 ft is the optimum length to surf well developed ocean swells and also is an excellent cruising sailboat. This hull has no keel, no permanent ballast and no conventional rudder.
The design lends itself to sailing craft to about 300 ft, motor vessels up to 500 ft for both inland and coastal use. As a surfing platform it can be designed in lengths of 25 ft to about 85 ft. It must comfortably fit on the forward slope of the swells it is designed to ride as a surfing platform.
The bottom of the hull can be fabricated using conventional methods in monel or copper-clad steel, aluminum or conceivably fiberglass. The reason for copper-clad is that the bottom must always be as smooth and clean as possible in order to get all the speed producing innovations to work right. The metal alloy monel has sufficient copper in its alloy to prevent marine growth.
The hull will go over 50 knots at
sustained speeds with sufficient wind and/or tradewind like swells.
This particular hull design (LWL of 50 ft) is 18 ft wide at the turn of
the bows into the sides and the beam continues to increase from the bows
at about a 4o angle with respect to the centerline to reach a beam of
about 21 ft at the stern. The bottom is substantially flat. The hull has no keel, no
permanent internal ballast, and it has no conventional rudder.
The flat bottom incorporates two steering and course stabilizing rotors on which sets of fins are mounted. These rotors are in lieu of a rudder. They are also used in special tandem routines while planing or surfing the hull.
The bows sections and the intersections of the bottom with the sides are equipped with multiple sets of pressurized air nozzles and the hull is equipped with multiple sets of crosswise venturi slots that suck air under the hull in great quantities as the hull speed increases above10 knots. The venturi arrays have much more sophistication to them but I can leave that discussion out of this epistle. The compressed air nozzles are needed to quickly bring the hull to planing speed. It must quickly crawl out of the water into planning attitude so a lot of air is needed to get her quickly up to speed and planing.
The venturi air flows can be controlled by damper valves so that the boat can be slowed down and not slide into the trough in front of the wave on which it is surfing.
The stern is equipped with large trim surfaces to help keep the stern configuration above the water at high speed to prevent wake turbulence while planing or surfing.
Along the straight flat sides (having 3.5o tumble home) are sets of water ballast scoops that are filled with water from the lee side just before the boat tacks so that the ballast water taken in ends up on the high side after the tacking maneuver has been completed. In this manner between 0 and 10,000 lbs can be taken on board as is needed according to the wind force and sails flown. Just before the next tack is negotiated this water is dumped and water is again taken on at the lee side just before the boat tacks. This disposable ballast weight is the equivalent of having up to 50 people sitting on the high rail. Idle crew members can also ride on the high rail. The wide-beamed and very stable boat thus can carry enormous amounts of sail and still retain a minimum heeling angle.
The idea is to keep the boat as level as possible to trap the air under the hull as long as possible. A 5o heel should be the maximum allowed. Tacking into the wind, however, should be exercised at low speed so that the relative wind comes more from the upwind direction allowing the boat to point steeper into the wind. The sides have a 4o angle with the lengthwise centerline of the hull; so that the lee side becomes keel when she heels. When the boat sails on the wind the boat is thus moving upwind at an increased angle of 4o; or really, creating a 0 o drift angle.. This is an advantage over any other sailing vessel.
Steering is done by rotors. Two rotors are used; one up front and one near the stern. The helmsman only has to turn the rotors about half the angle of a conventional rudder. The great advantage of these rotors is that one can turn both rotors upwind while sailing close to the wind causing the boat to crab or crawl upwind while yet retaining full efficiency of the sails.
The water ballast tanks are also important in trimming the hull while surfing. The stern should be a little deeper in the water for good steering and planing stability. While surfing large ocean swells the stern rotor is locked into mid position to serve as a course stabilizer while the front rotor and/or the outer trim surfaces at the stern can be used to control the heading angle with respect to the movement of the swell.
This hull can climb onto the front of a swell and ride it all across the ocean in the trade wind sections of the world or at the fringes of heavy storms, and then it is making between 45 to 55 knots over long stretches. Since this hull can surf any time during bad weather there is never a chance of it capsizing. It is always under full control while riding with the brute forces of wind and swells.
In mono-hull design it is in a super class by itself.
This super shallow, super fast hull
design was derived from my 42 ft cruising hull design. I had a 1/8
scale radio-controlled model made of this 42 ft LOA, cruising boat
that has forward and stern rudders. That model hull did go to windward as
anticipated; although it is a very difficult task to perform with a
radio-controlled sailing model.
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Page created on 12 16 2009 - last revised on 07-18-2010
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© 2006 Copyright Johannes P. and Carol A. van Krieken. All rights reserved. |