Ships – Spars – Masts and masting
Patent
1980-11-01
1983-01-25
Blix, Trygve M.
Ships
Spars
Masts and masting
114103, 114 39, 114108, 114 94, B63B 1500, B63H 910
Patent
active
043697267
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a sailboat mast of the essentially parallel two-piece type, one piece being fixed and held by standing rigging and the other being movable relative to the fixed piece.
Since the air stream along the leeward side of the sail stalls directly behind a conventional mast, a disturbance results at that point, increasing the drag. It is known to counteract this drag by selecting a suitable cross section for the mast or by other measures. Such other measures include making the mast rotatable, enabling the luff of the sail connected to the mast to be turned into the direction of the apparent wind (cf. Juan Baader, (Sailing Technique), published by Delius Klasing, 1973, pp. 68-71). It is also known to design the sail in such a way that it forms a pocket near the mast, thus forming sheet areas tangential to the cross section of the mast, at which the air stream does not stall. However these known measures reduce the possibility of rigging the mast to the hull by means of shrouds, because the pocket or the rotatability of the mast make it impossible to attach a spreader for the shrouds.
The invention has therefore the objective of designing the mast of a sailboat in such a way that it interferes as little as possible with the wind stream at the leeward side of the sail while allowing it to be rigged to the hull by means of shrouds and stays.
A further object of the invention is to enable the portion of the mast carrying the luff of the mainsail to bend aft at the top when that is desired to make the sail more suitable for particular sailing conditions.
Briefly, at or near the mast top, means are provided for guiding and guidably supporting at least the upper portion of the aft part of the mast, which carries the sail, and connecting that mast part to the upper portion of the forward mast part in such a way as to permit the aft mast part to be bent away from the forward mast part.
In one embodiment, the aft mast part is enveloped by a pocket or a sleeve formed from the sail, in which case the sail can lead off from the lee side of the mast to reduce drag from air turbulence without requiring the aft mast part to be rotatable. In that embodiment, the aft mast part may be of ovoid cross-section.
In another embodiment, the aft mast part is equipped with a slot or a track for attachment of the luff of the sail and is mounted rotatably about its longitudinal axis. In this embodiment, the aft mast part is preferably of circular cross-section.
The forward surface of the forward mast part is preferably of eliptical profile, with the major axis of the elipse lying in the longitudinal vertical mid-plane of the hull. Its aft surface is preferably concave to accommodate the aft mast part.
The means of guiding and connecting the aft mast part to the forward mast part at or near the top preferably takes the form of a cap fitting firmly on the top of the forward mast part with an aft extension containing a slot running astern from the mast center, so that the top of the aft mast part, shaped to provide a pin fitting into the slot, will be guided fore-and-aft therein. Lines and sheaves can conveniently be provided therein for trimming the top of the aft mast portion forward and astern for shaping the sail to meet wind conditions.
The invention is now described in greater detail by means of embodiments which are shown in the drawings, in which:
FIG. 1 shows a horizontal cross-section through the mast designed according to the invention and the sail forming a pocket, extending tangentially to the cross-section of the mast on the leeward side where it prevents the air stream from stalling behind the mast;
FIG. 2 shows a horizontal cross-section through a differently designed mast to which the main sail is attached by its luff in conventional manner, and wherein the luff can be moved either to the port or startboard sides of the mast;
FIG. 3 shows a horizontal section through the mast to illustrate the different widths of the zones of disturbance which result from different profile designs of the mast at the same an
REFERENCES:
patent: 133072 (1872-11-01), West
patent: 2561253 (1951-07-01), Coates
patent: 3835804 (1974-09-01), Jackson
patent: 3882810 (1975-05-01), Roeser
patent: 4112865 (1978-09-01), Carn
patent: 4143611 (1979-03-01), Hayhurst
patent: 4267790 (1981-05-01), Hood
Blix Trygve M.
Keen D. W.
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