the historic implement of world exploration, has within itself many
new horizons that beckon for pursuit, but you have to be willing
to venture past charted waters." -
quote from Gary Hoyt has never been more illuminating than today,
when I introduce a new motorsailing design that sports 'another
unusual sailing rig'. An inventive and resourceful gentleman, Tom
Perkins, has 'ventured past charted waters' to bring us a modern
version of the old square-rigger, the DynaRig. He has done it in
a big way with a real-life 'proof-of-concept' aboard his innovative
and fabulous new 290' superyacht, Maltese
prior 'mast-aft ketch' had elicited notable resistance among members
of the conservative sailing community, but I retain that discussion
here on the website for those who can't grasp the newest concept
of a free-standing, square-rigger. The DynaRig's application to
a multihulled vessel is addressed under the new section, "DynaRig
MotorSailer". The selling this new design and rig should be
quite a bit easier following the prototyping provided by Maltese
Soar With Us Into The Future
a Mast-Aft Sailing Rig
by Brian Eiland
five years ago, I was a younger fellow aspiring to become a sailing
yacht designer. I was particularly interested in ocean going, cruising
boats. I would devour every reference I could find on what made
sailboats work. With keen interest I followed new developments on
the racing circuits, believing that this was the incubator of fresh
new ideas to speed our progress across the seas. Surely this breeding
ground would bring significant evolution to the sport of sailing
and the art of designing.
contraire", I became disillusioned so soon. Bruce King's fantastic
twin, asymmetrical, bilgeboard development, disappeared in little
over a year. Prof. Jerry Milgrams cat-ketches were afforded a similar
welcome. Truely different sail rig innovations were totally discouraged,
and numerous other design innovations were "rated" out
of existence by handicap racing rules. Ocean
going boats were not being designed to "mother-ocean's
rules", but rather to some arbitrary, man-created, racer/cruiser
thanks, let me look elsewhere. A group out of England, AYRS, Amateur
Yacht Research Society came to my attention. A relatively new group
of multihull enthusiast and their new publication, "Multihulls
Magazine", also caught my attention. Here were some sources
of true experimentation, innovation, and creativity; and subsequent
evolution of the art of sailing, unbridled by handicap rules.
Today, look at the French and their fantastic ocean racing boats
both mono- and multi-hull; exciting innovation.
nature's onward march to better itself by slowly rejecting less
efficient characteristics of the whole, and either replacing them
with more efficient offspring, and/or redefining the whole as an
entity. Change comes so sloooow in traditional sailing. Look
how long it took the traditionalist to adopt the fully battened
mainsail that multihulls have long been exploiting for the better
part of 25 years. Did they just resist acknowledging it because
it was foreign to them, or was it the handicap rules. I suspect
both, but there is no doubt to its superiority; ah evolution!
before you get too comfortable with this full-batten mainsail idea,
realize that I do here intend to lay seize upon the sacred mainsail
of the Bermudian rig.
of the most influential books I had read was, "Sailing Theory
& Practice", by C.A. Marchaj. He subsequently published
another, "Aero-Hydrodyamics of Sailing". Both of these
books are the definitive technical source of what makes a sailboat
sail. And one other book, "The Art & Science of Sails",
by Tom Whidden and Michael Levitt, correctly describes the slot-effect
between the jib and main sails as explained comprehensively by the
aerodynamicist Arvel Gentry. In other words almost all the other
sailing books are wrong, and many of today's best sailors can
not describe correctly the aerodynamic interaction between
the headsail and the mainsail.
With Marchaj's book as my technical
guide, I began a search for alternatives to the traditional
Bermuda rig. Fore to aft sails must be retained for their windward
ability, and the single-masted rig would be preferred for its simplicity.
There are three basic positions for a single-masted sailboat: in
the bow ~~ which is a cat boat, in the middle ~~ which is the bermudian
sloop or cutter, or in the stern ~~ which is a ....? As Garry Hoyt
noted, "the fact that this stern-placed rig has no official
name attests to its almost complete lack of popularity". But
maybe placing this aerodynamic hindrance at the rear of the sailplan
makes sense? Years ago Victor Tchetchet experimented with it calling
it the "mastaft" rig. Garry Hoyt, world renown for his
cat rigged Freedom boats, built a rear masted prototype he called
the "Delta 26". In 1964, a McCurdy & Rhodes 46' "staysail
ketch" stepped the mast aft to eliminate headsail overlap and
permit the genoa to be self-tending. Prout catamarans have made
use of mast aft rigs (albeit very conservative, small sail-area
rigs) for years. And finally a "staysail cutter" rig proposed
by a maritime artist and historian, Melbourne Smith had a significant
impact on my thought processes.
real driving force to develop an alternate rig was the many negative
characteristics attributable to the mainsail:
The Bermudian mainsail operates behind a mast at its leading edge.
Mast induced turbulence renders totally ineffective,
the first 1' ~ 2' strip of sail area all way up the luff of
the sail. This is a sizable area not doing work for you. Want
simply and dramatic proof; go rent a Hobie (or any other) cat
and take it for a sail with its mast restrained from rotation.
On the same point of sail, let the mast rotate and experience
the acceleration as the addition sail area comes into play.
As much as the top 15% of the narrow, triangular head of
the mainsail is useless behind the proportionally larger mast
profile. Not only is this sail area ineffective, but the aero-configuration
induces significant drag. Modern multihulls have been cutting
this upper portion of the mast height off, and adding a 'fat headed'
mainsail. Even the old 12 Meter "Lionheart" exploited
Almost universally, clumsy booms and all their associated
vangs, mainsheets, travelers, outhauls etc, etc. are utilized.
Lots of (excessive) hardware and many occasions for this hardware
to interfere with the sailor's bodies themselves.
Conventional booms excessively flatten the foot of the mainsail,
and are often oversheeted, contributing significantly to the
leeway forces. I once had a copy of a test on a Morgan 41'
Out Island ketch , where upon removing the mainsail, the boat
lost only 1/2 knot of speed, but cut its leeway in half (from
11 to 6 degrees). A staysail was then rigged between the masts
in place of the mainsail, and the boat regained 1 knot of speed
while retaining its decreased leeway.
The draft pocket of the main is inclined to the vertical such
that the sail drives forward and downward. On reaches and broad
reaches this contributes lots of downward pressure
on the hull(s), and particularly the bow(s).
Fully battened mains are definitely much more efficient, but pay
a price in additional hardware, and a significant weight
penalty. In larger boats these sails are not easily raised
by man power. And unless they're attached to a rotating mast,
they still suffer a significant loss of effective sail area.
Mainsails do not come down or go up with any ease unless
the boat is pointed into the wind. And this shortcoming is exacerbated
in heavy weather.
just those characteristics above, we really do have to call to question
the use of a mainsail at all. No wonder the normal design practice
when drafting a rig's C.E. (center of effort) evaluates the genoa
at twice the effectiveness of the mainsail.