New Balance Rig sail?

THEN LINK TO PAGE:

http://www.balancedrig.com/designer.html



The BALANCED RIGTM is a self-tacking, free standing, balanced rig. This reduces the need for deck hardware as it is a self-contained sail frame. The rig is balanced, creating less load on the main sheet.

By using end plates at the top and the bottom of the rig, we have made the sail more efficient. The end plates guide wind over the powering part of the sail, increasing the sail’s efficiency and power. The low center of effort and the reduced height of the mast creates less heeling moment and reduces the need for deep draft and heavy ballast.

The engineering principles of the BALANCED RIGTM give you a mechanical advantage increasing sail control and ease of tacking. You can have all these advantages with a cost comparable to a custom rig. The ease in handling and fast tacking make it amazing.

Easy
Easier to sail than a traditional rig. One control line for both sails. Self-tacking and self-tending with just a turn of the tiller or wheel. The sails can be furled and reefed similar to a traditional rig.
>

Improved Performance
End plates generate more power. Self tacking jib makes for fast tacking and controlled gybing. This power is
balanced and the sheet load is reduced by %50. The low center of effort and the reduced height of the mast creates less heeling moment and reduces the need for deep draft and heavy ballast
>

Less Maintenance
The BALANCED RIGTM requires less rigging, sails and deck gear – reducing maintenance and downtime for repairs.
>

Safer
The BALANCED RIGTM is balanced, reducing force loads on the sails and rigging, and lightening the load on the single control sheet. This makes for a safer, more reliable and more enjoyable sailing experience.The free-standing BALANCED RIGTM means that there is no standing rigging to fatigue or fail.
>

The BALANCED RIGTM also allows excellent forward and all-round visibility under sail for maneuvering, navigation, safety, and sailing enjoyment.


boat building
Included on this page is information from the designer's notebook that may be of interest. The following text and graphics are excerpts from the book:

Aero-Hydrodynamics of Sailing
C.A. Marchaj
Dodd, Mead & Company • New York, 1979

The additional notes and highlights in overlay were made by
the inventor of the Balanced Rig™.
"The foot of the average mainsail is trimmed at angles of attack of 20 degrees or more. Thus, the flow over the lower chords is potentially separated. As we move up the mast we see that the chord angles of attack gradually decreases to values which are below the stall point. concomitantly, the thrust-to-heel ratio becomes more favorable.

One more glance at Fig. 2.130 may convince us that, contrary to these popular suppositions, the upper not the bottom part of the sail is potentially prone to an early stall. The old saying, 'what the eye doesn't see the heart doesn't grieve over', partly explains why the induced flow effects are underestimated by sailing people.
main sail
'For all its aberrations, the evidence of senses is essentially to be relied upon, provided we observe nature as a child does - without prejudices and preconceptions, but with that clear and candid vision which adults lose and scientists must strive to regain' - (Sir Peter Medawar)

In order to decrease the induced drag of a triangular sail, we should more nearly approach elliptic loading and this ... would mean making the upper half of the sail more heavily loaded. With this end in view, it would be necessary to have higher angles of incidence near the sail top than near the boom. However, with current sail control arrangements this is very difficult, if not impossible, to achieve. For an ordinary, highly tapered, triangular sail such setting is impossible.

It appears that by their very nature triangular sails penalize light crews greatly in conditions when the 'spilling' wind technique cannot be avoided.

jib
The Bermudan rig ... consisting of triangular sails, having a maximum chord at the foot and tapering almost uniformly to a point at the sail head, although very simple from a practical point of view is, from the standpoint of aerodynamics, inferior ... Very severe tapers may lead to aerodynamic characteristics much inferior to those of rectangular sails such as, for instance, that incorporated in the rig of Pen Duick III shown in Fig. 2.122.

If the potential possibilities in developing more power with relatively low heeling moment are appreciated, the long passage ocean racing of 'Around the World' type might well lead to an entirely different concept of offshore racing rig - something along the Pen Duick III line (Fig. 2.122) with lower aspect ratio sail of various planforms.
If the potential possibilities in developing more power with relatively low heeling moment are appreciated, the long passage ocean racing of 'Around the World' type might well lead to an entirely different concept of offshore racing rig - something along the Pen Duick III line (Fig. 2.122) with lower aspect ratio sail of various planforms.

Where the close-hauled course is not the most important performance feature and the maximum available lift coefficient becomes of preeminent value, low aspect ratio gaff-headed or even square sails may prove superior.

sail
The examination of figure ... 2.131 reveals, for example, that the rectangular foil, as compared to triangular ones, has more uniform distribution of the local lift coefficient, c1, and its tip parts, operating at lower effective incidence angles, produce lower c1 than the remaining part of the foil. By allowing a certain amount of washout, to which every sail has a natural tendency, a relatively close approximation to the elliptical loading, may in the case of a rectangular sail, be easily achieved. These characteristics of a rectangular planform are exactly opposite to those of a triangular one.
... another way of approximating an elliptic planform [is] by means of curved spars. The same effect can also be achieved by employing more efficient planforms than triangular, such as rectangular and trapezoidal shown in figure 2.122 ... It is rather a pity that gaff-headed sails have become almost completely ousted from the sailing scene. Certainly, the rating rules have in this respect a more profound effect on the shape of sails than the aerodynamic requirements or wind in all its moods. The penalty incurred for example by the sail measurement system on the width of headboard of the mainsail or length of its top batten is so high that it virtually precludes any attempt to improve the aerodynamic effectiveness of the modern tall rig. Those curious prohibitions, which after years of enforcement became part of sailing tradition, effectively discouraged ocean racing people from making experiments with unorthodox rigs which could have led to the development of less tall but more efficient rigs. So triangular sails prevail.
example by the sail measurement system on the width of headboard of the mainsail or length of its top batten is so high that it virtually precludes any attempt to improve the aerodynamic effectiveness of the modern tall rig. Those curious prohibitions, which after years of enforcement became part of sailing tradition, effectively discouraged ocean racing people from making experiments with unorthodox rigs which could have led to the development of less tall but more efficient rigs. So triangular sails prevail.
In practice, foils have a definite span and two or perhaps one free tip (as in the case of a spade rudder or fin keel attached to the bottom of the hull). No matter how the foils are mounted, vertically on the hull like sails or fin keels, or more or less horizontally like hydrofoils or wings, fluid in motion follows the universal inclination to flow from high pressure to low pressure regions by every available path. Examination of the flow pattern round any foil of finite span ... shows that at the foil tips the air or water tends to flow round the end from the underneath (or windward) surface where the pressure is higher than the ambient pressure, to the upper (or leeward) surface where the pressure is lower. The result of this is threefold:
sailing
boat building
1. The foil surface near the tip is much less efficient at producing lift.

2. This decrease in lift is accompanied by an increase in drag.

3. An additional disturbing air movement developing towards the tips modifies the direction of the oncoming flow near the foil, hence the effective angle of incidence along the foil span changes, as do lift and drag.
When the endplates are removed, the flow will tend to spill over the free ends, as indicated in the right part of Fig 2.84 B, i.e. from the side where positive pressure exists to the suction side distinguished by negative pressure. Such a flow wipes out the pressure differences at the tips and reduces it over the entire span of the foil.


Lanchester clearly understood this phenomenon when in 1897 he secured patent No 3608 covering the use of end plates, called by him 'capping plates', at the wing tips to minimize the pressure losses there - six years before the Wright brothers' flight. In the patent specification Lanchester describes the capping plates's action, to stimulate as far as possible the condition of a foil operating two-dimensionally in order to minimize the dissipation of pressure.
(fig 51) This sail A was demonstrated to be superior to a similar sail without end plate B, since the total force Fta was inclined forward of Ftb. This is equivalent to saying that the induced drag was less by an amount delta D, resulting in sail A having about 15 - 20 percent more driving force than sail B.

Triangular sails, as we shall see are thus notable examples of the worst planform from a purely aerodynamic point of view.



WELLYDECKHAND

 

It's really nothing new. Herreshoff used flat booms a century ago. I also saw that rig in use in the late 70's in multihulls. It is efficient within a narrow angle of sail. For different angles of sail the trim angles should also change. In beating, reaching and running the aerodynamic requirements change. With sails that can't be trimmed, the efficiency is the same or less than a square rig. I can't see any major advantage compared to the square rig.

 

I agree that a sail shaped like a simple triangle is very inefficient aerodynamically, however with the advent of full length sail battens in big boat sails as well as dinghys, who have had large roach/head sails for decades, we are seeing more elliptical shaped mainsails. Compare recent America's Cup boats with those of the 80's. It might have evolved earlier but for the problem as to what to do with usual single backstay on earlier large yacht rigs.
The Balanced Rig as you show will be useful in some situations, (cruising, I would think), but is unlikely to catch on to any great extent.

 

Someone should have done *all* the homework ...

There are good references about what size the end plates have to be to make them work, the ones shown in the photos look too small to be very effective.

In order for the plate to work the foils must be sealed to the end plate, gaps are no good.

In real life, sailboats require a variable area sailplan. I don't see any provision for reefing.

This looks like another RGYD to me.

If they had spent as much time with the science as they did with the slick website they might have a design that would work. Gotta love bears of small brain that launch half baked ideas based on partial understanding, every now and then they come up with a winner. This is not one of those times.