Sail and rigging for a sailing-apparatus

The sail is formed by a structure of stiffening elements comprising ribs r over which a sail-cloth zd is tightened to constitute a substantially stiff wing-like sail. The ribs r and girders l give the sail the correct profile and shape. The symmetrical sail is arranged to rotate and be mounted on top of the mast m on which it is able to hinge. The mast m is secured to the sailing-apparatus zt and able to hinge in one or more directions. The steering and control are done by exercising a moment around the centerpoint of the windforces by the sailor with the aid of handles or bows b. The mast m can be omitted and its functions fulfilled by the sailor, except when steering takes place with the aid of sheets. The sail can be composed of more than one profile and also be equipped with tails and fins. One variation has an adjustable angle between sail and mast m that can be locked in a chosen position. Another variation has a sail to mast connection sliding along the sail that can be locked in a chosen position.

The invention is concerned with a sail for propelling a sailing-apparatus 
over a surface, said sail having a frame, wherein a sailing-cloth is 
tightened over said frame and whereby the underside and the upperside act 
as windwardside respectively as leeside, and may be formed by separate 
cloths, wherein the sail is rotatable and hingeable with the aid of 
steering means in all directions with respect to a supporting body like a 
mast or so. 
The classic sail has a fixed mast rigged on a sailing-apparatus. For the 
purpose of tightening and positioning the sail, usually stiffening means 
like for instance a boom, and sheets are being used. 
A disadvantage of a fixed mast and a sail positioned with sheets is that 
when the ship lists under the influence of the wind, the sail moves to a 
different position, relative to the wind in the sense that the resultant 
of the windforces acting on the sail is not any more parallel to the 
surface of the water but has a downward component, or when an upward 
component was existing, this component is reduced. 
When rigging a sailboard, the mast is placed with a flexible joint allowing 
it to hinge in all directions. The sailor must keep the mast in an upright 
position. A split boom is used to tighten the sail between the mast and 
the end of the split boom, at the same time it serves as a handle by which 
the sail is steered. Because of the O-shape of the split boom, room has 
been created for the sail to curve in the desired manner under the 
influence of the wind. Because of this rigging, it is possible to give the 
mast such an inclination that the wind exercises an upward directed force 
on the sail so that notably the sailboard experiences less resistance in 
the water. 
To this method of rigging some drawbacks are attached: 
To have the sail functioning optimally it is necessary for the wind to 
approach the sail over its maximum width. This means that the mast must be 
positioned rectangular to the wind-direction. This cannot always be 
achieved, a classic sailing-boat for instance looses this position when it 
starts leaning to the wind and a sailor would have to move his mast 
forward or backward which would also result in moving the reaction of the 
windpressure on the sail and hence would result simultaneously in luffing 
or falling. In fact steering of a sailboard is being done by moving the 
mast in one of these two directions. 
By reducing the angle between the mast of a sailboard and the 
water-surface, measured in a plane perpendicular to the wind-direction, 
the vertical component increases and the horizontal component, responsible 
for the driving-force, decreases. The angle is determined by the sailer by 
less or more leaning overboard whereby he compensates with his own weight 
the moment exercised by the wind on the sail. The angle is therefore also 
determined by the strength of the wind and cannot be chosen independently. 
When gybing or going about, the two sides of the sail change function and 
consequently the sail must be able to belly out in two directions, making 
it difficult to optimize the sail-profile and in fact virtually only 
single cloth profiles are being used. 
For existing sailboards, going-about creates more problems than for an 
ordinary sailing-boat with a fixed mast and boom, because the sailor 
cannot duck in a simple manner under the sail; he has to walk around the 
mast or tilt the sail much forward and manipulate the sail over himself. 
In both cases the manoeuver requires time and skill. 
Alternative rigging devices and sails have been proposed. U.S. Pat. No. 
3,455,261 describes a "kite board" whereby the sail is replaced with a 
flat triangular kite-type sail with a T-shape frame connected to the 
sailing board, or not. The sail is held in position with ropes as is done 
usually with kites. 
German Offenlegungsschrift No. 28 33 616 describes a rig for a sailboard 
with a triangular sail with booms in the two leading edges and a 
connecting framework. 
French patent application No. 7922941 describes a triangular sail with a 
T-shape frame and a kind of mast with either an extremely forward or 
backward location. 
A triangular sail with a strong V-shape of about 60.degree. between the 
left wing and the right wing with a frame consisting of booms situated in 
the leading edges, a central boom and interconnecting framework has been 
published and demonstrated. 
In all cases the triangular sail is held by its frame and finds a point of 
support and pivots on top of a mast, if any. 
Above triangular sails may have improved going-about features, but lack 
properly curved and shaped sails and have insufficient steering facilities 
which becomes apparent later. 
This invention provides for the ultimate sail and rigging to the extent 
that an optimum sail shape and profile is achieved resulting in the 
highest efficiencies possible yet stable and equipped with complete 
steering facilities enabling the sailor to direct and hold the sail in the 
position he wishes, rectangular to the wind, manoeuvering the sail for 
stability reasons without sacrificing the angle of inclination under which 
the sail provides the required lift and free to choose a ratio between the 
vertical and horizontal component. 
The sail according to the invention is characterized in that said frame is 
formed with one or more ribs and girders, which together with the cloth(s) 
form a substantially stiff wing-type sail, in that the point of support 
coincides with or nearly with the point forming the design-pressure center 
of the windforces acting on the sail when sailing, and in that said 
steering means to be controlled by the sailor are formed by stiff bows 
and/or handles or the like, fitted to the frame and situated in a plane 
substantially parallel to the sail and distant from said point of support 
and said centerpoint of wind-pressure and distant at opposite sides of 
said points, whereby said points are arranged to be adjusted freely with 
respect to the sailing apparatus, for which purpose said supporting body 
like the mast or so is placed hingingly in at least one direction on said 
sailing-apparatus. A sail as described maintains the required aerodynamic 
wing-type profiles independent of the windforce, by means of a 
substantially stiff framework of ribs and girders and the cloth(s), in 
which the profiles and inclinations may change slightly towards the 
sail-ends and may have moderate V-shapes if any. 
To achieve an acceptable shape and the required profiles, a minimum of two 
girders and one rib or one girder and two or more ribs are foreseen. 
In principle, ribs and the sail can have any type of profile and varying 
from a single-cloth sail to a double-clothed profile. Also can be chosen a 
composite profile, composed of more than one profile, and for instance 
air-gaps. Various constructions of tails, fins and steering-areas can be 
added. The sail can be made symmetric with respect to the centre-rib. One 
or more ribs and girders give the sail its required stiffness. In case a 
mast is used, the sail will be secured to the top of the mast on or near 
the location of the design-pressure centre of the windforces acting on the 
sail, in such a manner that it can rotate and hinge in all directions. The 
point of rotation can be at any location between the sail and the 
sailing-apparatus. 
The mast may be of a stiff construction for instance made of a stick or a 
hollow pipe, or for instance to able to absorb a pulling force only, when 
constructed like a chain, spring or rope, or for instance be able to 
withstand tension and some pressure forces, but is resilient to bending 
moments, for instance by having an elastic body around a limiting chain or 
rope-type construction and a series of hollow cylinders, thus allowing the 
mast to bend when loaded in that manner, so that injury and damage will be 
avoided. The mast may be of a telescoping structure with end stops, 
fixation means and be possibly preloaded by a spring or so. The bottom of 
the mast is placed on the deck for instance with a universal joint or for 
instance only hinging forward and backward if some steering limitations 
are wanted. If desired the mast may even be omitted and its functions 
taken over by the sailor. 
The steering and directing of the sail can take place in various ways. For 
a sail of the dimensions of for instance a sailboard, direct steering can 
be done by the sailor with the aid of handles or bows or any device 
connected with the sail in such a manner that any moment can be executed 
around the pressure-centre of the wind-forces acting on the sail. 
Therefore handgrips or other means have a stiff connection with the sail 
and are located in a plane substantially parallel to the sail and distant 
from said point of support and said centerpoint of wind-pressure and 
distant at opposite sides of said points so that a moment in all planes 
perpendicular to the sail area can be executed without relocating hands. 
For larger sail-apparatus sheets can be used to position the mast and the 
sail. 
The most important parameters for positioning the sail can now be set 
independently: By moving the mast backward and forward, luffing and 
falling can take place without changing the relative position of the sail 
to the wind, so that the sail will maintain the optimum position. 
By rotating the sail around a vertical axis the correct position of the 
sail in relation to the wind direction can be found and the correct angle 
of inclination by rotation around an axis parallel to the sail. 
By rotating the sail around an axis parallel to the wind direction, the 
horizontal and vertical components of the resultant of the windforces on 
the sail will change in opposite directions, so that an independent choice 
of the relative size of these components can be made. 
By hinging the mast sideways, that is to port or starboard, while moving 
the sail parallel to the wind, a variation in the moment executed by the 
sail around the length-axis of the sailing-apparatus will result, so that 
the stability can be achieved independently of the aforementioned motions. 
Warping of the sail can be counteracted by the sailor by placing the hands 
on the right location or with the use of bracing-wire. If desired, warping 
can be introduced in a similar manner. 
Going about has been simplified with the introduction of this sail and 
rigging, the sailer tips the sail to the other side, the lower end becomes 
the higher end and vice versa, while the sailor hardly has to duck when 
passing the sail or moving the sail over his head. 
As a consequence of the distribution of the windforces over the ribs and 
girders, these components can be made light, the mast is subjected only to 
tension and possibly some pressure and can thus be light. Convenient 
profiles can be chosen for the girders and the ribs, suitable for the 
expected windforces and required stability, and for instance to reduce the 
drag, to make posssible simple connections between the parts, to achieve 
the correct bending stiffness for the sail, to attain simple methods for 
assembling and for easy change of parts, etc. As material for these parts 
can be used for instance wood, metal, synthetic material or composite 
material. 
By shortening the mast slightly under half the length of the sail, jamming 
of the sail on the sail-apparatus is avoided when for instance the sailor 
looses has control over the sailing-apparatus. 
The hinging connection between the mast and the sail can be made sliding 
along a girder or a rib and if desired equipped with a locking device, so 
that the point of support can be adjusted with regard to the sail. 
Damages can be avoided or reduced if the handles or bows required for 
steering can hinge away from the mast. In order to maintain the proper 
position during steering, limiting means are applied to limit the turning 
angle towards the mast, executed for instance with bracing wires. 
Since fixed steering devices such as handles or bows are used that are also 
capable in withstanding pressure forces, the mast can be omitted and the 
sailor can take over its functions. By also dispensing of deck and 
sailing-apparatus all connections between the sail and the surface over 
which the sailor wishes to move, are replaced by the sailor. For the 
purpose of transmitting reaction-forces such like for instance derived 
from the wind and weight-forces, to the carrying surface, the sailor can 
make use of for instance floaters with a fin mounted under his feet in 
case of moving over water, or skate-like structures for instance mounted 
under his feet in case of moving over ice, or structures with wheels for 
moving over other hard surfaces.

Other characteristics or details of the invention are described in the 
claims and in the following description of prefered embodiments of the 
invention. 
Of a sailing-apparatus with a wing-type sail as described above, some 
samples are given in the following FIGS. 1 through 5. In all drawings the 
mast is marked with m, girders marked l.sub.1, l.sub.2, etc., ribs marked 
r.sub.1, r.sub.2, etc., bows for steering marked b.sub.1, b.sub.2, handles 
marked h.sub.1, h.sub.2, bracing-wire s.sub.1, s.sub.2, etc., the 
sail-cloth marked with zd. 
FIGS. 1a and 1b show a wing-sail with a sail-cloth stretched between a 
front-girder l.sub.1 and an end-girder l.sub.2. The sail is put in the 
right profile by three ribs, r.sub.1, r.sub.2, r.sub.3. By lifting the two 
ends of end girders l.sub.2 slightly upwards, the profile of the sail 
turns slightly towards the tips of the sail. The sail is tightened by use 
of a wire running through eyes in the end-leech of the sail and around the 
end-girder, any other method of stretching the sail-cloth can be used. The 
front-girder is placed in the front-leech of the sail, in order to reduce 
the drag. Bows for steering are secured to the ribs r.sub.1 and r.sub.3 
with hinges. The pins of the hinges of each bow are running in line with 
each other. Bracing wires s.sub.1 and s.sub.2 are holding the bows in 
position during sailing. In the example as shown in FIGS. 1a and 1b, the 
sail has a single cloth which can be secured to the ribs with the aid of a 
rope or canvas sewed to the sail such that a casing is formed fitting the 
rib. Examples of such constructions are given in the FIGS. 3 and 4a to 4d. 
Point of hinging is marked p on all drawings. Rotation of the sail is made 
possible by rotation of the top half of the coupling in its slot sl in 
such a manner that pulling forces are absorbed by a removable ring. 
Instead of a sleeve-bearing, for instance a ball-bearing or roller-bearing 
can be used. 
FIGS. 2a, 2b and 2c show a plan without an end-girder but with a 
main-girder instead, running through the entire span of the wing-sail. 
Tightening the sail-cloth can be arranged for instance by tightening a 
rope or wire which runs through the aft-leech of the sail over the ends of 
the girders and ribs. With this construction, a reduction of the drag is 
achieved. Here also a single or double cloth can be used. For steering two 
handles h.sub.1 and h.sub.2 are shown. A side-view of the middle-rib shows 
that the handles are mounted with hinges to the middle-rib. Bracing-wires 
ascertain that the handles can execute the required couple around the 
point of the resultant of the windforces, the sailor will pull the handles 
towards himself, so towards each other. 
FIG. 3 shows a wing-sail with sailboard zt in action sailing close to the 
wind. In this plan the main-girder is simultaneously the front-girder, 
while a shorter girder maintains the distances between the ribs near the 
second and aftermost bow. 
FIGS. 4a to 4d show in three views a more complex but also dismountable 
wing-sail. Ribs r.sub.e1 and r.sub.e2 at the tips of the sail are 
end-ribs, forming a sail-rim and connect the girders. The risk of damaging 
the sail is now reduced, it opens also the possibility of using a special 
end-profile. The shape of the profiled ribs is illustrated in FIG. 4c. The 
sail-cloth is double and tightened at the tips of the sail and along the 
aft-leech via the ends of the ribs. The ribs are locked in by 
cloth-profiles sewed to the sail. The sail-cloth is cut partially at one 
end so that the ribs can be inserted in their chambers, after which the 
chambers can be laced up, closed by hooks or closed in any other fashion, 
if required under a cloth cover to reduce the drag, see FIG. 4b. The 
possibility of an uninterrupted cloth does exist, the ribs are inserted in 
chambers for instance, made of cloth not tapered towards the opening, see 
FIG. 4d. For instance with a rope, wire or thread, with or without 
elasticity, the chambers can be closed. The main-girder is also inserted 
in a cloth-chamber as well as through openings in the ribs. The ribs are 
connected to the front-girder for instance with a pin. The end-ribs 
r.sub.e1 and r.sub.e2 are secured to the girders for instance with pins 
and screwed tight if so required. Subsequently the double cloth can be 
tightened between the end-ribs, along the ribs and along the aft-leech. 
Mast and bracing-wires are not shown in FIGS. 4a to 4d. 
The Examples given are kept simple, V-shapes of the wing-sail, complex and 
composite profiles, tails, fins and steering-areas for instance are not 
shown. Many variations on the given examples are possible based on the 
same principle. For instance a reduction in the degrees of freedom can be 
accepted without effecting the advantages of this sail and rigging 
notably. For instance the angle between the mast and the sail can be 
secured in a chosen position. 
In FIGS. 5a and 5b is given as example a bracing-wire sd running from one 
wing-half to the other through a bracing wire guides such as a 
locking-device k of a conventional structure situated in the mast m which 
can be activated or released with a motion of a foot or hand.