Ships – Spars – Masts and masting
Patent
1996-06-28
1997-11-18
Swinehart, Edwin L.
Ships
Spars
Masts and masting
114107, B63B 1500
Patent
active
056876661
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The invention concerns a design of a mast for a sailboat, wherein the mainsail's mast rope is inserted into a hollow profile on the outside of the mast.
In most existing mast designs the position of the mast profile in front of the plane of the sail causes turbulence or the creation of a back eddy over the sail's lee side. Wing sail rigs with a rotating mast have almost no turbulence, since their aerodynamic design is very good, but this rig is only suitable for multi-hull boats. The field of turbulence is extremely wide and extends over the entire height of the sail, and turbulence in this area results in very poor tractive power for this part of the sail. The aerodynamic conditions are highly unsatisfactory.
SUMMARY OF THE INVENTION
The object of the invention is to improve these conditions and thereby provide increased power to the mainsail of a Bermuda-rigged sailboat.
By means of the solution according to the invention an aerodynamic design is obtained which is close to ideal. The field of turbulence is completely eliminated and the construction provides full tractive power over the sail, and in addition tractive power over the actual mast construction up to the foremost point on the mast. The construction approaches the most ideal aerodynamic design, the bird's wing shape.
The construction consists of a round mast tube about which an aerodynamically shaped profile can rotate within a sector of 180 degrees, and inside which are various fastening alternatives for the mainsail, in which roller reefing on the inside of the profile is a possibility. This a further advantage which is achieved with the special design according to the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail by means of an embodiment which is illustrated in the drawing:
FIG. 1 is a side view of the uppermost part of a mast designed according to the invention,
FIG. 2 is a detail drawing of the top of the mast viewed from in front,
FIG. 3 is a side view of the lower part of the mast,
FIG. 4 is a view from in front of the mast with a fastening device for shroud and horns of the crosstrees,
FIG. 5 is the mast viewed from above in a section A--A in FIG. 1,
FIG. 6 is a cross section through mast and profile at the intersecting line A--A in FIG. 1, and
FIG. 7 is a cross section along line D--D in FIG. 3 through boom and mast/profile.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The mast design is illustrated in the drawing where FIG. 1 shows a side view of the mast's 1 uppermost part down to and including the fastening device for shroud and horns of the crosstrees. The horns of the crosstrees are only shown as a cross section where they are situated in the centre of the bracket. The uppermost part of the profile is illustrated in a "transparent" manner, the roller stay and the attachment of the sail being visible, since this version of the profile is designed internally for a roller mainsail.
FIG. 2 illustrates the top of the mast viewed from in front. The top shrouds are attached to a transverse beam in order to provide space for the rotation of the profile.
FIG. 3 illustrates a side view of the lower part of the mast from the neck of the sail down to the attachment on deck. Details will be presented in the following description.
FIG. 4 is a view from in front on an enlarged scale of the fastening device 24 for shroud and horns of the crosstrees 23.
FIG. 5 illustrates the mast on an enlarged scale viewed from above, from a section through A--A in FIG. 1. The ring with which the profile is attached is not included, nor is the inside of the profile. Through the horns of the crosstrees 23, which are made in one piece, can be seen the stippled attachment bracket 24 to which the horns of the crosstrees 23 are screwed. On the underside on each side of the bottom shrouds can be seen. The profile has been swivelled out the maximum distance to the port side, and the turning sector and the profile's position to starboard are illustrated as
REFERENCES:
patent: 3345969 (1967-10-01), Purvis
patent: 4149482 (1979-04-01), Hoyt
patent: 4930434 (1990-06-01), Clausin
patent: 4949660 (1990-08-01), Despries et al.
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