A mast-aft rig is a
sailboat
A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture.
Types
Although sailboat terminology ...
sail-plan that uses a single
mast set in the aft half of the
hull. The mast supports fore-sails that may consist of a single
jib
A jib is a triangular sail that sets ahead of the foremast of a sailing vessel. Its tack is fixed to the bowsprit, to the bows, or to the deck between the bowsprit and the foremost mast. Jibs and spinnakers are the two main types of headsail ...
, multiple
staysail
A staysail ("stays'l") is a fore-and-aft rigged sail whose Sail components#Edges, luff can be affixed to a stays (nautical), stay running forward (and most often but not always downwards) from a mast (sailing), mast to the deck (ship), deck, the b ...
s, or a
crab claw sail
The crab claw sail is a fore-and-aft triangular sail with spars along upper and lower edges. The crab claw sail was first developed by the Austronesian peoples some time around 1500 BC. It is used in many traditional Austronesian cultures in Islan ...
. The
mainsail
A mainsail is a sail rigged on the main mast of a sailing vessel.
* On a square rigged vessel, it is the lowest and largest sail on the main mast.
* On a fore-and-aft rigged vessel, it is the sail rigged aft of the main mast. The sail's foot ...
is either small or completely absent. Mast-aft rigs are uncommon, but are found on a few custom, and production sailboats.
Comparison to other single mast rigs
Many mast-aft rigs utilize a small mainsail and multiple staysails that can resemble some
cutter rigs. A cutter is a single masted vessel, differentiated from a
sloop
A sloop is a sailboat with a single mast typically having only one headsail in front of the mast and one mainsail aft of (behind) the mast. Such an arrangement is called a fore-and-aft rig, and can be rigged as a Bermuda rig with triangular sa ...
either by the number of staysails, with a sloop having one and a cutter more than one, or by the position of the mast, with a cutter's mast being located between 50% and 70% of the way from the aft to the front of the
sailplan
A sail plan is a description of the specific ways that a sailing craft is rigged. Also, the term "sail plan" is a graphic depiction of the arrangement of the sails for a given sailing craft.>
In the English language, ships were usually describe ...
, and a sloop's mast being located forward of the 70% mark. A mast-aft rig could, based on headsail count, be considered a variation of the sloop or cutter, or, based on mast position, a unique rig.
Advantages
In the typical
Bermuda rig
A Bermuda rig, Bermudian rig, or Marconi rig is a configuration of Mast (sailing), mast and rigging for a type of sailboat and is the typical configuration for most modern sailboats. This configuration was developed in Bermuda in the 1600s; the t ...
, the sails located in front of the mast generally deliver a higher percentage of the driving force. The
stay
Stay may refer to:
Places
* Stay, Kentucky, an unincorporated community in the US
Law
* Stay of execution, a ruling to temporarily suspend the enforcement of a court judgment
* Stay of proceedings, a ruling halting further legal process in a tri ...
that supports the
leading edge
The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...
of the sail causes far less
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
than a mast, resulting in better airflow across the lee side of the sail. To take advantage of this fact, Bermuda rigs are shifting towards larger fore-sails and smaller mainsails. Fore-sails include
jib
A jib is a triangular sail that sets ahead of the foremast of a sailing vessel. Its tack is fixed to the bowsprit, to the bows, or to the deck between the bowsprit and the foremost mast. Jibs and spinnakers are the two main types of headsail ...
s,
genoas and
staysail
A staysail ("stays'l") is a fore-and-aft rigged sail whose Sail components#Edges, luff can be affixed to a stays (nautical), stay running forward (and most often but not always downwards) from a mast (sailing), mast to the deck (ship), deck, the b ...
s. The
cutter, with its use of multiple foresails, achieves the same goal of placing a higher percentage of the sail area in staysails.
By moving the mast toward the back of the sailboat, designers can increase the size and driving power of the more efficient foresails. The
mainsail
A mainsail is a sail rigged on the main mast of a sailing vessel.
* On a square rigged vessel, it is the lowest and largest sail on the main mast.
* On a fore-and-aft rigged vessel, it is the sail rigged aft of the main mast. The sail's foot ...
is reduced in size or eliminated altogether. An advantage of using foresails, also called staysails, is that they may be rigged for
roller furling
Roller furling is a method of furling (i.e. reefing) a yacht's staysail by rolling the sail around a stay. Roller furling is typically used for foresails such as jibs or genoas.
A mainsail may also be furled by a similar system, whereby the sai ...
. This allows the sail(s) to quickly and easily be deployed and
reefed by pulling lines. The sail rolls up around the stay. This simplicity and easy operation is one of the main attractions of the mast-aft rig.
By reducing the mainsail in size or eliminating it altogether, the aft mast rig squarely minimizes or completely solves the problems associated with
batten
A batten is most commonly a strip of solid material, historically wood but can also be of plastic, metal, or fiberglass. Battens are variously used in construction, sailing, and other fields.
In the lighting industry, battens refer to linea ...
s. Battens enable designers to increase the size of mainsails by pushing the mainsail away from the mast. However, the forces of the battens pushing against the mast make it more difficult to raise or lower the mainsail. On larger rigs, "batten cars" are needed to overcome these forces.
By eliminating the battens and associated batten cars, the material cost savings for a typical 60-ft catamaran can be as much as $12,000 AUD. Aft-mast rigs with no mainsail also require fewer winches to raise and lower sails, and no winches to move the boom. When "Hot Buoys" converted from a Bermuda rig to an aft-mast rig 5 winches were no longer required.
For rigs with no mainsail, there is also no
boom
Boom may refer to:
Objects
* Boom (containment), a temporary floating barrier used to contain an oil spill
* Boom (navigational barrier), an obstacle used to control or block marine navigation
* Boom (sailing), a sailboat part
* Boom (windsurfi ...
. This saves the cost of the boom, and hardware and lines associated with the boom. More importantly, eliminating the boom is a matter of safety. The second leading cause of death on sailboats is the boom. Booms cause injuries and deaths directly and indirectly by knocking people overboard. Even when stationary, booms represent a hazard. According to a German study, "boom strikes were the most common cause of sailing injury overall". Another aspect of safety is in regards to the elimination of the lines and hardware to control the boom. With fewer lines and less hardware on the deck there are fewer items to trip over or trap fingers and hands.
Disadvantages
Mast-aft rigs depend on a large foresail which, like any sail, becomes more difficult to manage with its size. This is particularly true when sailors do not want to use
roller furling
Roller furling is a method of furling (i.e. reefing) a yacht's staysail by rolling the sail around a stay. Roller furling is typically used for foresails such as jibs or genoas.
A mainsail may also be furled by a similar system, whereby the sai ...
, e.g., because they do not want to compromise speed.
Mast-aft rigs are viewed as unconventional, and since recreational sailors often choose boats based on what "looks" right, mast-aft rigs face resistance in the recreational market. Racing sailors will use whatever is fastest within class rules, and class rules are generally very closely tied to the conventional Bermuda rig.
Another disadvantage of the mast-aft rig, when set up with no mainsail, is the drag on the mast. While the mast may interfere with the airflow around the mainsail, the mainsail also serves to reduce the drag on the mast. By not having a sail attached to the trailing edge of the mast, the mast becomes a significant source of drag. Additionally if there is no mainsail there is difficulty in
heaving to
In sailing, heaving to (to heave to and to be hove to) is a way of slowing a sailing vessel's forward progress, as well as fixing the helm and sail positions so that the vessel does not have to be steered. It is commonly used for a "break"; this ...
or coming to rest with sails set and boat "weathercocked" with bows into the wind. This can make the boat much more vulnerable in storms when a partly furled foresail has exactly the wrong effect on boat position relative to wind and waves while hove-to and this, though less of an issue for racing, is still an issue for long-distance cruising.
The performance of the sail is dependent on having a forestay which is taut. If the forestay is allowed to slack, the sail will lose its airfoil shape and not perform as well. This requires heavy rigging with high tension which adds stress to the overall sail rig system; this is not really a disadvantage per se but rather a parameter to consider if rigging a sailboat to use a mast-aft rig.
Commercial production examples
An early successful mast-aft design was built by
Prout Catamarans, Ltd. The ''Snowgoose'' models were offered with a mast-aft rig, and it boasted a number of features that made short-handed sailing easier than with a standard Bermuda rig. Broadblue Catamarans Ltd. now owns and makes two of the Prout designs, which still come standard with the mast-aft rig.
RB Power & Sailing of Thailand offers two aft-mast catamarans. Model "HK-40" is 40-ft long and model "HK-55" is 55-ft long. They were designed by Albert Nazarov.
Most aft-mast sailboats are either catamarans, or trimarans. An exception is the "4.8 monomaran" designed by Kees Radius's. A ""monomaran"" is a single hull with no ballast and a dagger board.
Commercially unsuccessful examples include the Delta 26 by
Gary Hoyt
Gary may refer to:
*Gary (given name), a common masculine given name, including a list of people and fictional characters with the name
*Gary, Indiana, the largest city named Gary
Places
;Iran
* Gary, Iran, Sistan and Baluchestan Province
;Uni ...
and the CS-24 by
Phil Bolger
Philip C. Bolger (December 3, 1927 – May 24, 2009) was a prolific American boat designer, who was born and lived in Gloucester, Massachusetts. He began work full-time as a draftsman for boat designers Lindsay Lord and then John Hacker in the ...
. Prototypes of both designs were constructed, but neither entered commercial production.
Ted Brewer
TED may refer to:
Economics and finance
* TED spread between U.S. Treasuries and Eurodollar
Education
* ''Türk Eğitim Derneği'', the Turkish Education Association
** TED Ankara College Foundation Schools, Turkey
** Transvaal Education Depa ...
's So-Du-It, designed for amateur home construction, had at least two examples constructed, but the anticipated offshore racing class never materialized.
Custom yacht examples
''Shotover'' is a 60-ft long racing catamaran with a 31-ft beam designed by Lock Crowther and built for Sir
Douglas Myer
Douglas may refer to:
People
* Douglas (given name)
* Douglas (surname)
Animals
* Douglas (parrot), macaw that starred as the parrot ''Rosalinda'' in Pippi Longstocking
*Douglas the camel, a camel in the Confederate Army in the American Civil ...
. This sailboat utilizes a mainsail and a small boom. For several years it held the fastest time in the
Brisbane to Gladstone yacht race
The Brisbane to Gladstone yacht race is held annually, starting on Good Friday. The premier blue water classic begins from Shorncliffe in Moreton Bay, Queensland, Australia, and finishes in Gladstone Harbour. Yachts compete for the Courier M ...
.
The sailboat now shuttles tourists to the
Monkey Mia
Monkey Mia is a popular tourist destination located about 900 km north of Perth, Western Australia. The reserve is 25 km northeast of the town of Denham in the Shark Bay Marine Park and World Heritage Site.
The main attraction are t ...
resort area off
Western Australia
Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...
.
''Hot Buoys'' is a 65-ft long cruising trimaran with a 40-ft beam. It was designed by Jay Kantola, and built by Richard and Kris Barrie of California. In 2010 it was converted by Philip Maise to an aft-mast rig with a self-tacking
crab-claw sail
The crab claw sail is a fore-and-aft triangular sail with spars along upper and lower edges. The crab claw sail was first developed by the Austronesian peoples some time around 1500 BC. It is used in many traditional Austronesian cultures in Is ...
. Video in External Links
Warick Collins, experimental boat builder, and inventor of both the tandem
keel
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
and the universal hull, now uses an aft-mast rig. ''"I believe that in due course this will have wide applications for motor-sailers, commercial vessels and sail-assisted passage-making on larger vessels of different types.''
"Lyra" is a catamaran built of
polycore panels that by 2011 had logged over 7,000 miles. Ian Campbell reported it tacked and went to windward very well.
With no boom to swing across, ''"accidental jibes are a ho hum event"''.
References
Further reading
*
{{DEFAULTSORT:Mast Aft Rig
Sailing rigs and rigging