Login| Sign Up| Help| Contact|

Patent Searching and Data

Document Type and Number:
WIPO Patent Application WO/2021/005420
Kind Code:
A segmented, unstayed rotating mast of sailing ships is extended and retracted like an automatic antenna. During reefing, each sail element folds centrally at the joints between two battens dividing each sail segment and lies down behind the underlying yard (and downwind of the underlying sail) or at the bottom of the sail bag. The mast including the sailbag can be rotated at the base, e.g. via a worm gear.

More Like This:
Application Number:
Publication Date:
January 14, 2021
Filing Date:
July 03, 2020
Export Citation:
Click for automatic bibliography generation   Help
International Classes:
B63B15/00; B63H9/08; B63H9/10
Foreign References:
Download PDF:

1. Telescopic mast for sailing boats and ships, which is designed to be unstayed and central- ly rotatable, wherein the mast is divided into segments which can be Telescopically pushed into one another.

2. Telescopic mast for sailing boats and ships as to claim 1 , wherein the mast segments are extended and retracted by means of semi-flexible racks or shear connectors

3. Telescopic mast for sailing boats and ships as to the above requirements, wherein the racks can be extended by guiding them in a helical slotted guide and rotating them.

4. Telescopic mast for sailing boats and ships as to claims 1 and 2, wherein the Telescopic mast elements are jointly extended and held in a vertical position by internally guided, adjust- able tensioning lines.

5. Telescopic mast for sailing boats and ships as to claim 1 and 2, wherein each mast seg- ment with its yard is individually operated with a semi-flexible rack.

6. Telescopic mast for sailing boats and ships as to claim 1 , wherein each mast segment is assigned a yard with a sail segment attached thereto.

7. Telescopic mast for sailboats and ships as to claim 1 and 2, wherein the yards are con- nected to the respective mast segment in a spaced manner by means of outriggers.

8. Telescopic mast for sailing boats and ships as to claims 1 to 3, wherein a respective sail segment is guided between two yards.

9. Telescopic mast for sailing boats and ships as to claims 1 to 4, wherein the sail segments have a central division, which are connected by two horizontal sail battens with a bead linking them.

10. Telescopic mast for sailing boats and ships as to claims 1 to 4, wherein the mast is rotat- ably mounted in the mast foot.

11. Telescopic mast for sailing boats and ships as to the above claims, wherein the rotation of the mast with the yards is effected mechanically with a worm gear.

12. Telescopic mast for sailboats and ships as to previous claims, wherein the rotation of the mast is carried out with a hydraulically operated extension arm at the lowest mast segment.

13 . Telescopic mast for sailing boats and ships as to previous claims, wherein the mast profile and mast elements are concentrically arranged one into each other and have an oval cross-section.

Telescopic square sail device

FIELD OF THE INVENTION The invention relates to a sailing device with a rotatable, unstayed, telescopically retractable and extendable mast with frames attached to each Telescopic element at a distance and with sails divided in the middle by two sail battens connected in an articulated manner, which are otherwise comparatively stiff.


Sails on boats and ships must be reduced in size (reefed) in high winds to prevent capsize or breakage of the rigging.

Various systems are known for this purpose, but so far the mast remains in one piece on all of them. On the one hand, this has the disadvantage of higher wind resistance, on the other hand, the increased centre of gravity and the springy masses of high masts cause unfavour- able sea behaviour, especially pitching in high seas.

Mast height is a decisive factor for the performance of sailing ships and yachts. The develop- ment of modem sailing yachts is initially aimed at improving propulsion in directions "close to the wind" [at an acute angle to the wind] with slim slup rigs and high masts. However, high masts mean high constructional and economic effort and they have disadvan- tages in seakeeping, especially due to increased pitching when the natural frequency of the mast system resonates with the immersion in wave formations.

Moreover, there is increased wind resistance during motoring, and masts and sheets maybe a source of noise when anchoring or berthing.

Really high masts and large sail areas therefore are only applied on competition boats, where differentiated sail setting and reefing is managed by a qualified large crew. in order to give masts sufficient strength at lowest possible weight, they are usually provided with bracings often outwardly (fore-, aft-, backstays, etc.) and inwardly (diamond stays, spreaders).

Stays, however, have the disadvantage of wind resistance and restrictions for possible sail positions, in addition to their expense. With modem laminated sails they also represent a permanent risk of obstruction and damage to the sails during manoeuvres. On the other hand, there are also masts without stays, e.g. on American Catboats. The dis- advantage of unstayed masts so far, however, is their strong deflection (under load) to lee- ward or a disproportionate thickness with the disadvantage of unfavourable wind resistance and turbulence, as well as the high weight of the mast, including the resulting constructional consequences.

Another problem of sailing ships is that masts cause increased air resistance during motor- ing: Sailing yachts with motor drive are therefore inevitably slower and less fuel efficient than motor yachts of comparable hull shape. In addition - due to the higher centre of mass - un- favorable seakeeping occurs due to stronger pitching and rolling, especially in swell, as well as increased wind noise while berthing.

Handling of sails with sheets and halyards seem to be old-fashioned, but so far without alternative. Particularly the handling of a main boom, which even on modem boats has to be adjusted with the help of sheets and bull pendant, foot tensioner and dirk or kicker, and still only allows a limited directional stability and sail trim, seems questionable.


In order to overcome these disadvantages, the task of the present invention is to find a sys- tem which limits the mast height to the respective requirements of sailing, i.e. which allows large mast heights and sail areas in light winds, but which limits the mast height in strong winds to the height required for a reefed sail and which keeps the mast as low as possible during motoring or anchoring etc. - and which also combines this with good sailing character- istics.

For this purpose, a system with an unstayed Telescopic mast is proposed, which is only fully extended in light winds, but retracts Telescopically as the wind pressure increases.

In the present invention, this is achieved by combining one Telescopic mast element each with spreaders attached to it at a distance.


Telescopic masts are already well known, initially as tubes inserted into each other, usually with a toggle lock on the upper edge of each tube element, to which the extension is fixed. However, this means that the mast would have to be extended to the desired height and fixed before it could be erected.

However, this would be insufficient for this and other applications. It must be possible to gradually raise the mast from its base. A simple form of this is known as a so-called crank mast, especially for mobile antennas.

Here a steel cable runs from the top of one segment around a pulley to the base of the next segment, from there to the top of the next segment and so on. By pulling on the rope the seg- ments are pushed apart and thus pushed up.

For this purpose, the pipe elements must either be manufactured with a distance between their diameters, or they must have formed beads so that the traction cables can run between the pipes - or they are guided along the outside of the pipes by deflection pulleys, which makes the structure difficult to transport and susceptible to faults.

Similarly problematic are rack and pinion lifting systems, such as used in some mobile cranes which - especially in the case of possibly cascaded lifting elements - require even more space between the pipe segments that are guided into each other On the other hand, it is also possible to keep the mast elements airtight and extend them with pneumatic or hydraulic pressure. The limits can then be set by bracing - which is neces- sary in some cases anyway. However, these are not applicable for the present case of an unstayed rotating mast. For heavy masts, such as on big mobile cranes, on the other hand, a hydraulic thrust ele- ment is usual (e.g. as to US 3,688,455 and US 4,489,838), which first pushes out one mast segment, couples this segment to a second one, then moves that segment and so on until all elements are extended. The effort involved here comprises the necessarily remote-con- trolled coupling elements, for which alone a group of patents has been applied, such as US 2,858,154 and US 3,464,169. However, the operation inevitably is time-consuming and thus not adequate to sailing maneuvers.

Not dependent on such coupling elements are designs with several, central rotary spindle elements, for example as to US 4,062.156, which, however, might be problematic due to their weight and the difficult to maintain toothed spindles located in the tubes and about whose actual design nothing was found out.

Furthermore construction and control of extension and retraction of Telescopic masts are also known, of automatically extendable antennas (e.g. as to DE 689136343 T2 resp. WO 88/11167): This is usually carried out by a semi-flexible toothed rack, which in retracted state is wound up in a rotatable, helical gate, and by rotation of it is extended and deflected into the mast and pushed up.

Telescopic masts for sailing ships are known in principle (e.g. US 4,998,498), although not yet for actuation during sailing. It is conceivable, however, that they were attempted, but failed (as to reports by Herreshoff in 1912) due to the problem of restricted mobility under load and inappropriate connections of mast and sail. Several attempts have been made, however, to design the yards in a variable way; conven- tionally by additional spars already in 19th century Tea clippers, as well as Telescopically as to US 5,146,864, but there is no information on how the corresponding sails should be reefed in and out (probably by curtain folding with rails or keeps [guide grooves] on or in the yards).


The inventive step here is to make the mast telescopic and rotatable.

For this purpose, the sails are attached in segments to frames in the same way as on classic tall ships, whereby the frames are each connected to the upper edge of their respective Tele- scopic mast segment via an extension arm. The individual sail segments are guided between the frames with variable tension, preferably by variably restricting rods inside the mast

This is done in such a way that the mast is extended to a desired height in its centre by a semi-flexible, toothed rod just like an automatic antenna or a guided pushing chain and turned by a worm gear at the base of the mast, . A steel cable is pulled along for each mast or for each mast element, which runs over a seg- mented reefing drum, which is released or tightened [put under tension] for reefing [reducing or hauling in the sails] depending on the desired pre-tension of the sails.

The sail elements, which are preferably stiff in themselves (although they may have a slight curvature) and for this purpose have a division in the middle with a flexible area between two sail battens, can then be pulled onto the respective yardarm below with separate reefing lines and fixed there; at the foot of the mast they are fixed in a sail holder (similar to a lazy bag), which acts like a lowermost yardarm and is turned with the mast. The possible rotation as well as the variable mast height require a mast that is designed with- out any bracing ropes. This is disadvantageous with regard to its load-bearing capacity and thus the maximum usable wind pressure, but this is compensated for by the possible quick adaptation to it (e.g. by anticipatory LIDAR measurement and integrated strain gauges) and by the better handling.

In addition, modem materials allow slim and highly resilient constructions. The mast can be turned to the wind together with its frames at the base of the mast, because it is unstayed, and the ship or boat can therefore be sailed high up in the wind [at a narrow angle to the wind] together with flat-trimmed sails.

This also makes it possible to“hold back” [position of the sail against the wind], which is oth- erwise only possible manually with small dinghies, and allow simple and agile manoeuvres - e.g. when mooring - which can be carried out even without motor ship propulsion.

The mast - here preferably designed with oval cross-sections of its elements - can be rotated, together with the lazy bag at the base of the mast, e.g. hydraulically or via a worm gear.


With this construction, the frames can also be slightly curved, which has recently proved to be very efficient, e.g. on the large yacht“Maltese Falcon”.

However, it is also possible to extend the individual mast segments at the top of the follower element by means of hoists deflected there (such as antenna crank masts), or to assign a telescopically extendable hydraulic element to each mast segment, as is the case with large mobile cranes.

It is conceivable here to assign a thrust mechanism to each mast element and thus to each yard in the form of a separate push rod or chain thrust element in the mast and thus to deter- mine the sail tension in a differentiated manner.

It would also be possible to design the tension of the sails differently, e.g. to make the lower sails more bulbous as required, while at the same time trimming the top sails flat.

In addition, it is of course possible to attach trimming lines at each yardarm [outer end of the yard] or at the ends of the battens, which hold the yard down against the drive of the racks or hydraulic cylinders and thus determine the tension of the sail.

However, this would make handling more difficult, requiring several helpers and a well-re- hearsed team. The adjustment of the sail surface and tension to the wind pressure can be done manually as to the sailor's feeling. Preferably, however, it is automated or at least supplemented with an- emometers and sensors - e.g. with laminated strain gauges for mast deflection - but prefer- ably with LIDAR systems calculating the expected wind pressure in advance to compensate for gusts.

Whether the actuation is electric or hydraulic depends on whether a hydraulic system is already provided or available in the ship (for drive, winches, anchor chain etc.) and can be extended accordingly. Basically, the trim of the sail can be determined by the tension of each yard in relation to the one underneath, so the sails can be trimmed flatter or more bulbous. The tension of the sails between the yards can be determined individually by one halyard [hoisting and tensioning line for sails] per yard (preferably guided in the mast), whereby the halyards end together on a tension plate at the foot of the mast, where they are fixed in a line stopper, curry clip or on a small, self-tailing winch. A joint change in sail tension is then effected by moving the tension plate vertically, e.g. with a crank drive.

In a preferred design, however, each mast segment has a separately designed retraction and extension device, whereby these are - electronically controlled - connected to each other. Here, one segment after the other is extended or retracted with a yardarm or sail batten and the sailcloth is laid on top of each other during reefing - e.g. folded centrally in alternating directions - on the lower yardarm in the sail holder, which is rotatably arranged with the mast at its foot.


The preferred embodiment of the invention is explained in more detail in the drawings Fig. 1 to Fig. 3:

Fig. 1 shows the mast 1 with its segments 2 to 7 in retracted condition, here with the attach- ments for the yards 17-22, the turning mechanism 15 and the sail holder (or lazy bag) 14.

Fig. 2 shows the mast with sails on yards in extended condition