Pyramid masts

Abstract

Embodiments of the inventive technology provide a sail powered craft having a high power to weight ratio. A preferred embodiment may involve three masts connected together at the top of the craft and spread apart at the bottom to form a pyramid. Each mast may have a corresponding sail. In at least one embodiment, the front windward sail uses the craft's angle of attack to provide downforce on an upwind surfboard. The downwind front sail may create lift and forward thrust, thereby preventing the downwind board from submarining. Certain embodiments may also include an upside down main sail with a flying boom.

Description

BACKGROUND

Most sailing vessels in the past have used stand-alone masts, located along the centerline of the boat. This requires very stiff and heavy masts, along with cables to help maintain the masts upright position. This construction technique limits the boats design, and increases the weight of the boat significantly because of the structure necessary to hold the heavy mast vertical. When the masts are self supporting and centered they have to be much heavier, given the high wind forces exerted on them. The heavier the mast; the heavier the boat structure needs to be, the heavier the keel needs to be, and therefore the greater the water drag. I goes without saying that; the greater the water drag, the slower the boat.

The biggest advance in the average speed of sailboats, over the last thousand years, has been the development of multi-hulled sailboats. Multi-hull designs are faster for two reasons: 1) the righting moment resisting the wind has better leverage with the wider stance, allowing for more sail area for a given weight; 2) the narrow hulls or out riggers have lower water drag. This increase in speed has changed the dynamics of sailing and there is no going back.

The weakness of current state of the art in high-speed sailboat design is; the fact that the boats are still too heavy. This excess weight generates too much water drag and prevents maximum speed from being attained. This weight comes from the boats structure required to resist the huge wind forces, being exerted on a central vertical mast, which is held in place by wires under tension. The force from the tension on these wires needs to be resisted by a strong beam in a bending moment. This design philosophy requires a very heavy beam or hull design, in order to work properly with any durability. This design philosophy is what I have changed with my new design.

Best Method:

There are three questions that came to me that prompted this new design:

• • 1) Why not resist or counter the righting forces of the wind on the main sail (the forces that try to tip over the boat) with more wind force, instead of the typical water forces that cause significantly more drag? If you can create counter forces and thrust forces together you can create more total thrust with less water drag.
  • 2) Why does a mast have to be vertical, a wind surfer does not hold his sail vertical when he/she is at maximum speed? In fact, the wind surfer uses the angle of the sail to lift the his weight and that of the board out of the water which reduces water drag and allows a faster maximum speed.
  • 3) How can I triangulate all the wind and water forces on a sailboat, in order to eliminate most structural bending moments, in order to reduce weight? This can't be done without triangulating the mast itself.
    The purpose of this new sailboat design is, to provide a very high (wind) power to weight ratio for a sailboat or any sail powered craft. The key to this design is the triangulation resulting from a three-sided pyramid structure, or tetrahedron shape. This is a very common shape found in nature, mostly at the molecular level, because of its inherent stability. The triangular tetrahedron structure provides the highest rigidity for the lowest weight, by transmitting most forces through compression and tensile forces on the masts and base triangle tubes themselves. The total triangulation minimizes bending moments of all tubes, allowing them to be much lighter than typical sailboat masts and structures.

By using three masts that are connected together at the top and spread apart at the bottom, in the form of a pyramid, the resulting triangulation reduces the weight of each mast as well as the weight of the entire boat. The outside corners of the base triangle of the boat are its strongest points. By spreading the masts out to each corner of the boats base the masts are connected directly to the strongest points. This eliminates the structure normally needed in the middle of the boat to support the single vertical mast that is attached to a normally heavy cross beam under heavy bending moment from the wires that hold the mast vertical.

Pyramid masts create large triangles that strengthen the boat above the water line reducing the weight of the boats hull structure. With the triangulated structure of the masts, each having their own sail, the boat can have a greater sail area for a given mass. The greater sail area will increase wind forces increasing the speed of the boat. The lower weight of the boat will reduce its water drag, also increasing the speed of the boat.

The front windward sail(13), uses the structures angle of attack, to provide downforce on the upwind surfboard(19). The downwind front sail(14) creates lift and forward thrust, preventing the downwind board(16) from submarining. This way both front stabilizer sails(13 & 14) resist the righting moment of the main sail(10), while providing additional forward thrust.

Wind surfing sailboards(16, 19 & 20) are designed to plane the surface of the water and provide very low water drag. The base triangle(17) provides a very wide stance at the front of the boat and narrow stance at the rear, effectively giving the boat a wide track and long wheelbase. The rear sailboard(20) is to be used primarily for steering, but the front two boards(16 &19) can be steered as well, to change the entire structures angle of attack to the wind.

The base triangle provides a big trampoline(8) for the enjoyment of multiple passengers. Though, the buoyancy of the surfboards(16, 19 & 20) may need to be increased in order to support a large number of passengers, at least when the boat is stationary. The base trampoline(18) will have to be designed to fold up. It will be too big in all dimensions to be transported in a normal vehicle, when open.

A unique aspect of the design is the upside down main sail(10), with the flying boom(12). This allows the top of the sail to be let out for better control of its angle of attack to the wind. The flying boom(12) can be made to rotate with the wind forces, to provide a more aerodynamic shape to the wind. This is similar to a normal rotating mast found on a catamaran. In this design, the boom(12) is the highest structural beam catching the highest velocity wind, therefore aerodynamics are most important for this part. The flying boom(12) is the only beam used primarily in a bending moment, but it is not part of the structure of the boat.

All the sails used in this design are very common shapes and easily attainable. The front two sails(13 &14) are just large windsurfing sails. The main sail(10) is just a conventional sail, used upside down. This aspect of the design makes it very easy to find existing sails, for testing different size versions of the boat, and for low cost of production. The triangular(21) structure around the front sails is similar to the conventional boom on a wind surfer. This triangle(21) is used to tension the front sail(13) and control its angle of attack to the wind.

By using three masts that are connected together at the top(11) and spread apart at the bottom, in the form of a pyramid, the resulting triangulation reduces the weight of each mast as well as the weight of the entire boat. The outside corners(15) of the base triangle of the boat are its strongest points. By spreading the masts out to each corner of the boats base(17) the masts are connected directly to the strongest points(15).

The tetrahedron shape is a triangle on all its faces; which makes it the strongest open structure known to man. Given we need the wind to blow through the structure on a sail boat, in order to power the sails, it is the best choice for the structure. This choice of structure is not obvious to the designers of sail boats because; sails at different angles to each other not easy to understand how to control because they can shroud the wind from one another. It is not obvious because in the past masts have always been vertical, for simple aerodynamics and good controls in varying wind conditions, in both directions. This design has the potential to break the world speed record for sailboats because of its power to weight ratio and its stabilizing front wing effects.

With three sails in combination, the sail area can equal that of a much heavier boat. The very high power to weight ratio of the boat will make it accelerate very fast. Top speed will be limited by the drag of the trampoline. A speed record attempt, with this design, will not have a trampoline net. It will use a driver's seat in the back of the base triangle.

Using a conservative design and built with aluminum spars this boat is expected to weigh only 600-700 pounds total. The rigidity of the structure can support sail surface area normally seen on a 3000 pound boat. If it were made from carbon fiber poles and had no trampoline the total weight could be less than 400 pounds.

This boat has the potential to be very fast. Along with that potential, from its high power to weight ratio, comes instability in gusty winds. One possibility to reduce the chances of flipping in wind gusts would be to have a crew of 2 people to control the boat. This way the main sails control and steering, can be handled by one person. The second person can control the two front sails, so that in significant gusts of wind the main sail can be let out and the stabilizing sails can be pulled tighter by the second crewmember to resist the flipping moment.

It is expected that one-person could sail this boat. The pilot or skipper could maintain control holding two ropes in one hand from the two front stabilizer sails, while holding the main sail rope or cord in the other hand. The steering would be best accomplished through a foot pedal mechanism. In a very large version of this design a computer may be required to control the three very large sails, in order to maintain stability in varying winds. The control system would work like the computer on a jet fighter; where the plane would be unflyable without it.

This boat is designed to be extremely transportable. It can be dismantled into its component masts. The trampoline can be hinged in the middle of one beam and be folded up. Together with the three surfboards, the masts, poles and trampoline can be put on a set of roof racks above the normal automobile. All the associated linkages, ropes and sails could be transported in the trunk of the car.

As for costs in high-volume, this boat could actually cost less than a catamaran of similar length. Using mostly standard components, like sails, surfboards, masts and poles, the cost to develop and test variations on the design, is also very low. Only the triangular trampoline and angled joints are unique to this boat. A dagger board slot does need to be added to the surfboards.

This boat is designed to be a very exciting and faster alternative to today's catamarans. A future version will be designed to go after the world speed sailing record. The basic design provides the power to weight ratio needed to beat the current world speed record. Given that second place overall, in the speed sailing record books is held by a wind surfer, this boat has all the elements needed for success at high speed.

Claims

1) Any sail equipped vehicle with two or more masts connected together at the top where two or more of those masts connect to the body structure or hull(s) of the vehicle off the center line of the vehicles direction of travel.

2) Any sail equipped vehicle with two masts connected together at the top and attached to the hull(s) of the boat off the center line at or near its widest structural points.

3) An vehicle of claim 2 where those two masts are attached to one or more other masts near the top to form a self supporting structure that does not require any other means of support to keep it standing under load.

4) Any sail equipped vehicle with one or more stabilizer masts, where the upper end of the stabilizer mast is connected to the main mast and the lower end of the stabilizer mast is connected to a structure off the center line of the vehicles direction of travel.

5) Any sail equipped vehicle with a tetrahedron like structure.

6) A vehicle of claim 5 that carries two or more sails.

7) Any sail equipped vehicle with a pyramid like mast structure that carries two or more sails.

8) An apparatus of claim 1, 2, 4, 5 or 7 where a mast is defined as any beam, post or pole, made of any material that can be put under tension and compression along its length, that can carry a sail.

9) An apparatus of claim 1, 2, 4, 5 or 7 where the vehicle can be defined as a boat, hydroplane, surfboard, car, sled, skate, plane, train or truck.

10) An apparatus of claim 1, 2, 4, 5 or 7 where the vehicle could have one or more hulls, or wings (hydroplane), or surfboards, that touch the water, ground or surface upon which it is riding.