Introduction
The Aegean rigging in a sailing boat is a
simple arrangement that provides for maximum driving force by use of the total
surface of the boom sail as a perfect airfoil. As such, exploiting new
materials, it can ultimately enable a friendly to the environment design of a sailing boat free of a
carbon content fuel.
A flat main sail rigging, consists
of a rigid boom with an embedded guiding rail with its runner-camber controller
(figure 1). The runner is controlled by a chain attached to it, moving via rotating
wheels at both ends of the boom. It can be stabilised at any position. Rotating
power is delivered to the wheel near the mast end of the boom by an outside power
source (by electric motor or manually). A flat surface sail with in-mast reefing
feature is attached to the runner at its clew end. The boom is positioned via the
main sheet at its optimum angle of attack to the apparent wind direction. The
sail camber is regulated by the position of the runner-camber controller according
to wind speed, so that the air flow around the whole surface of the sail is as
linear as possible. This layout also ensures the stability of the sail to wind
parameters variations.
In larger vessels, boom position and sail camber
are determined by a computerized system controlled by sensors at the leech end
of the sail. It adjusts the boom angle of attack and the cumber of the sail in
accordance with the apparent wind parameters for the attainment of a close to
linear air flow.
The Aegean
Rigging itself requires negligible electrical power and stored energy and
none in case of manual handling.
Claim: The
Aegean rigging, as described above as an arrangement around a flat sail is
new according to EPO Article 54.
The proposal, as opposed to a fully attached boom sail
rigging, delivers an optimal airfoil shape for the whole sail surface and
significant reduction of wake turbulence due to the pressure differential
between its two sides at the boom end. More importantly by streamlining its
lower part, it provides significant increase in the effective sail surface. These
modifications result in an increase in propulsive power and a lowering of the
sail’s center of effort.
When compared to a vessel equipped with a traditional
rigging arrangement, and for the same sail area, the invention provides relative benefit from:
·
The effective use of the whole surface of a flat main sail.
· The possibility to use modern sail materials including solar cells
imbedded foils.
·
A boat righting couple reduction due to lower
sail center of effort.
·
Sharper tacking behavior, due to an increase of
the effective sail surface.
· Smaller ballast and thus lighter and faster boat.
The system can be incorporated
on new boats and larger commercial vessels utilising this particular
rigging of boom supported sails to augment their propulsive
power but can also be
deployed with moderate modifications on existing vessels delivering a significant gain in sail
power.
Prior Art
An example (figure 3) illustrates how sails are typically arranged on an
sailing boat with one mast. The design shown consists of sails attached to the
mast, located ahead of amidships. A triangular sail ahead of the mast is raised
or pre-hoisted along a forestay which is braced approximately from the bow to
near the mast tip. The clew as the free end of the leech and foot of the sail
is hauled tightly by means of a jib sheet so that the sail can adopt the most
favorable possible aerodynamic profiled shape to take advantage of the apparent
wind.
The draft of this head sail also energetically intensifies the lee flow of the subsequently positioned mainsail.
This ensures the most extensive possible
wind deflection without the lee flow becoming separated from the mainsail,
and thus minimises the risk of creation of complex
wake turbulence, which would result in an important loss
of
sail
driving force.
The characteristic configuration of the sail profile and its angle of attack is crucial
for the specific propulsion power per square meter of sail area. Utilising
current practices and current sail, mast and boom technology, the maximum
production of driving force is achieved in the upper part of
the boom sail. In the area near the
boom, the propulsion-bringing flow profile is
increasingly deflected - and ultimately interrupted - by the turbulence produced by the boom.
Neither the angle of attack in the luff zone of a well-positioned main sail, that is close to the incoming
wind direction, nor the
outflow angle at the leech following the forward-driving flow deflection inside the sail are
similarly directed to the angle of attack
of the boom attached to the sail. Thus, appreciable power losses occur
in the transition zones from the sail, even when profiled as correctly as
possible, in the upper region, to the straight connected boom. Modern sails design has reached its limit in remedying
this deficiency. This problem is accentuated as the otherwise usable
downdraft of the head sail does not meet an ordered lee flow on the rear side of the main sail.
In conclusion, when the main sail is attached
to a standard profiled straight rigid boom head, in addition to serious wake turbulence formed along the foot of the sail,
caused by the exchange
of air from the luff-side to the lee side
with the boom’s presence, more important
turbulence losses result from the distortion of the linear flow on
the sail surface near the straight boom at serious expense of drive energy (figure 4). Wind tunnel research confirms
this situation.
Description of the invention
The proposal, described hereinafter as the Aegean Rigging, is designed
to address and minimise the effect of
the aforementioned
disadvantages. It also creates a boom sail
rigging that ultimately
will be decisive for the design of a sailing boat free of a carbon content fuel
and thus friendly to the environment
The generic concept is demonstrated in figures 2.
The invention consists of a rigid sail boom with an embedded
guiding rail with its runner-camber controller. The boom, as driven by the main
sheet, is positioned at optimal angle of attack to the apparent wind. The
runner is moving via rotating wheels at both ends of the boom by a chain
attached to it on both sides. It can be stabilised at any position. Movement
and positioning of the runner is secured by the wheel near the mast end of the
boom that is rotated by outside power source (figure 2). A flat surfaced sail
with in-mast furling feature is attached to the runner-camber controller at its
clew end. The aim
of the runner is to achieve, under given apparent wind speed, the most efficient airfoil shape of the total surface area of the sail thus maximising propulsive
force. Optimum efficiency is attained through the use of modern foil materials
for the sail, including foils with impregnated solar cells. This provides the possibility
for additional energy stored during daytime and the use of a complementary
electric propulsion plant, avoiding a combustion engine.
Other runner-camber control mechanisms can be arranged to achieve its
generic control function.
In its complete form, the rigging includes a computerised control
system that determines and positions the boom
and the guiding rail runner according to apparent wind parameters.
The above description broadly only reproduces the more important features
of the present disclosure.
As a simple package, the system can easily be
installed on existing vessels. In this form, the invention requires no
modifications to the remaining sail rigging systems and results in significant gains in
sail power.
Given the generic basis of this proposition, the embodiments of the disclosure are not restricted to this description and the outline of the
example construction. Other
embodiments can also be implemented within the scope of the invention as defined by the claim and executed
in different ways. Furthermore, it is understood
that the phraseology and terminology used is only used for the description and not as a restriction
as it does not demonstrate finer details of the system’s design deemed
unnecessary for the purposes of this application.
The exemplary embodiments
of
the
invention
are
explained in more detail with reference to the
drawings.
List of Figures
Figure 1 shows the Aegean rigging layout
Figure 2 shows the main sheet and runner-camber controller details
Figure 3 shows a prior art arrangement
Figure 4 shows a wind tunnel experiment
Description of the drawings
Figure 1 shows proposed
arrangements of the boom rigging. The boom spar with its kicking strap is attached
in the usual manner to the mast and controlled by the main sheet. The sail is
attached forward to the mast via a reefing gear and to the boom via the runner,
the position of the latter controlled by the guiding rail mechanism.
Consequently, the boom angle relative to the apparent wind is controlled by the
main sheet and the camber of the sail, adjusting to the wind strength, is
controlled by the position of the runner. Need for minor adjustments of the
boom to control the leech shape is taken care by the kicking strap.
Figure 2 shows the main sheet and runner-camber controller details. The
main sheet is attached to the boom in the usual manner. The runner of the
guiding mechanism is attached to the clew of the sail.
Figure 3 shows a prior art arrangement. Sails are
typically arranged on an average sailing boat with one mast located ahead of
amidships with sails attached to it. A head sail ahead of the mast is raised
along a forestay. Its clew is hauled tightly by a jib sheet and this helps the
sail to adopt an aerodynamic profiled. The draft of this sail also intensifies the lee flow of the subsequently positioned mainsail.
This ensures the most extensive possible
wind deflection without the lee flow becoming separated from the mainsail.
The characteristic configuration of the sail profile and its angle of attack is crucial
for the specific propulsion power per square meter of sail area. Utilising
current practices and current sail, mast and boom technology, the maximum
production of driving force is achieved in the upper part of
the boom sail. In the area near the
boom, the propulsion-bringing flow profile is
increasingly deflected - and ultimately interrupted - by the turbulence produced by the boom. Neither the angle of attack in the luff zone of a well-positioned main sail, that is close to the incoming
wind direction, nor the
outflow angle at the leech following the forward-driving flow deflection inside the sail are
similarly directed to the angle of attack
of the boom attached to the sail.
Figure 4 shows a wind tunnel experiment. It is apparent that when the main sail is attached
to a standard profiled straight boom head, in addition to serious wake turbulence formed along the foot of the sail,
caused by the exchange
of air from the luff-side to the lee side
with the boom’s presence, more important
turbulence losses result from the distortion of the linear flow on
the sail surface near the boom at
serious expense of drive energy.
Figure 1
Figure 2
Figure 3
Figure 4
