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Genoa (sail)
Encyclopedia
The genoa or jenny was originally referred to as the 'overlapping jib' or the Genoa jib, being named after the city of Genoa
as explained below. It is a type of large jib
or staysail
used on bermuda rig
ged craft that overlaps the main sail, sometimes eliminating it. It is used on single-masted sloop
s and twin-masted boats such as yawl
s and ketch
s. Its large surface area increases the speed of the craft in moderate winds; in high wind conditions a smaller jib is usually substituted, and downwind a spinnaker
may be used. The feature that distinguishes a genoa from a jib is that the former extends past the mast, overlapping the mainsail when viewed from the side.
The term genoa is often used somewhat interchangeably with jib, but technically there is a clear delineation. A jib is no larger than the foretriangle, which is the triangular area formed by the mast
, deck
or bowsprit
, and forestay
. A genoa is larger, with the leech
going past the mast and overlapping the mainsail. To maximize sail area the foot of the sail is generally parallel and very close to the deck when close hauled
. Genoas are categorized by the percentage of overlap. This is calculated by looking at the distance along a perpendicular line from the luff of the genoa to the clew, called the LP (for "luff perpendicular"). A 150% genoa would have an LP 50% larger than the foretriangle length. Sail racing classes often specify a limit to genoa size. Different classes of genoa have overlaps; a number 1 genoa may be a 150%, and a number 2 genoa, 125%. Jibs are also defined by the same measure, with overlaps of 100% or less. Under Performance Handicap Racing Fleet
rules most boats are allowed 155% genoas without a penalty.
has been around for several decades now, and as the name suggests it is a hybrid between a genoa and an asymmetrical spinnaker
. A brand name of North Sails, the gennaker is a cruising sail based on the Code 0 spinnakers used on racing boats. Gennakers and similar code 0 variants offered by other makers are even larger than genoas (200% overlaps are not uncommon) and they have a much greater camber
for generating larger amounts of lift when reaching
. Flat cut gennakers can be effective for angles as low as 60–70 degrees. Spinnakers perform much better when running because the main sail blocks the wind of gennaker above 135–150 degrees.
(1890–1969) on his 6 m R-yacht "May-Be" in a regatta in Genova (Copa Tirreno). Salén capitalized on an opening in the rules allowing the foresail to be far more overlapping than the previous norm. He went on to win the Gold Cup in Oyster Bay later that year also using the overlapping jib. For many years afterwards the sail was known as the Salén jib, or the Swedish jib, as well as genoa, while the name genoa (genua) was used early on in the Swedish language. Salén also pioneered the like-sided spinnaker as well as the up/downhaul on the spinnaker pole.
The invention of the overlapping jib, that is also close to the deck to optimise airflow, is much older however and was rediscovered for yachting by Salén. This type of jib was in use for centuries by the fishermen in the Netherlands with their Botter type ships. The fishermen relied on the combination of a large jib while fishing so the mainsail could remain unused. After fishing the fisherman's jib helped to get the fish to markets fast.
A correct explanation of the interaction between jib and mainsail was published by aerodynamicist and yachtsman Arvel Gentry in 1981, and "is much more complicated than the old theories imply". This states that the widely believed explanation of the slot effect is "completely wrong" and shows that this is not due to the venturi effect
(or "valve effect" to use Curry's term) accelerating the air in the slot. Instead it is shown that the air in the slot is slowed down and its pressure increased reducing the tendency of the mainsail to stall, that the mainsail reduces the air pressure on the lee side of the jib accelerating that airflow, and that the mainsail increases the angle at which the air meets the luff of the jib, allowing the boat to point higher. Gentry points out that proper understanding of sail interaction allows better sail trimming.
Sven Salen's crew on the 6 meter was another Swede by the name of Gunnar Jacobson who worked as an architectural designer in Los Angeles until his death.
Genoa
Genoa |Ligurian]] Zena ; Latin and, archaically, English Genua) is a city and an important seaport in northern Italy, the capital of the Province of Genoa and of the region of Liguria....
as explained below. It is a type of large jib
Jib
A jib is a triangular staysail set ahead of the foremast of a sailing vessel. Its tack is fixed to the bowsprit, to the bow, or to the deck between the bowsprit and the foremost mast...
or staysail
Staysail
A staysail is a fore-and-aft rigged sail whose luff can be affixed to a stay running forward from a mast to the deck, the bowsprit or to another mast....
used on bermuda rig
Bermuda rig
The term Bermuda rig refers to a configuration of mast and rigging for a type of sailboat and is also known as a Marconi rig; this is the typical configuration for most modern sailboats...
ged craft that overlaps the main sail, sometimes eliminating it. It is used on single-masted sloop
Sloop
A sloop is a sail boat with a fore-and-aft rig and a single mast farther forward than the mast of a cutter....
s and twin-masted boats such as yawl
Yawl
A yawl is a two-masted sailing craft similar to a sloop or cutter but with an additional mast located well aft of the main mast, often right on the transom, specifically aft of the rudder post. A yawl (from Dutch Jol) is a two-masted sailing craft similar to a sloop or cutter but with an...
s and ketch
Ketch
A ketch is a sailing craft with two masts: a main mast, and a shorter mizzen mast abaft of the main mast, but forward of the rudder post. Both masts are rigged mainly fore-and-aft. From one to three jibs may be carried forward of the main mast when going to windward...
s. Its large surface area increases the speed of the craft in moderate winds; in high wind conditions a smaller jib is usually substituted, and downwind a spinnaker
Spinnaker
A spinnaker is a special type of sail that is designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of...
may be used. The feature that distinguishes a genoa from a jib is that the former extends past the mast, overlapping the mainsail when viewed from the side.
Definition
Mast (sailing)
The mast of a sailing vessel is a tall, vertical, or near vertical, spar, or arrangement of spars, which supports the sails. Large ships have several masts, with the size and configuration depending on the style of ship...
, deck
Deck (ship)
A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary deck is the horizontal structure which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface...
or bowsprit
Bowsprit
The bowsprit of a sailing vessel is a pole extending forward from the vessel's prow. It provides an anchor point for the forestay, allowing the fore-mast to be stepped farther forward on the hull.-Origin:...
, and forestay
Forestay
On a sailing vessel, a forestay, sometimes just called a stay, is a piece of standing rigging which keeps a mast from falling backwards. It is attached either at the very top of the mast, or in fractional rigs between about 1/8 and 1/4 from the top of the mast. The other end of the forestay is...
. A genoa is larger, with the leech
Parts of a sail
In sailing the parts of a sail have common terminology for each corner and edge of the sail.-The corners:In a triangular sail, the upper point is known as the head; the halyard, the line which raises the sail, is attached to the head...
going past the mast and overlapping the mainsail. To maximize sail area the foot of the sail is generally parallel and very close to the deck when close hauled
Points of sail
Points of sail describes a sailing boat's course in relation to the wind direction.There is a distinction between the port tack and the starboard tack. If the wind is coming from anywhere on the port side, the boat is on port tack. Likewise if the wind is coming from the starboard side, the boat...
. Genoas are categorized by the percentage of overlap. This is calculated by looking at the distance along a perpendicular line from the luff of the genoa to the clew, called the LP (for "luff perpendicular"). A 150% genoa would have an LP 50% larger than the foretriangle length. Sail racing classes often specify a limit to genoa size. Different classes of genoa have overlaps; a number 1 genoa may be a 150%, and a number 2 genoa, 125%. Jibs are also defined by the same measure, with overlaps of 100% or less. Under Performance Handicap Racing Fleet
PHRF
Performance Handicap Racing Fleet is a handicapping system used for yacht racing in North America. It allows dissimilar classes of sailboats to be raced against each other...
rules most boats are allowed 155% genoas without a penalty.
Handling issues
Maximizing the sail area causes more difficult handling. It may be harder to tack a genoa than a jib, since the overlapping area can become tangled with the shrouds and/or mast unless carefully tended during the tack. Genoas are very popular in some racing classes, since they count only the foretriangle area when calculating foresail size; a genoa allows a significant increase in actual sail area within the calculated sail area. In boats where sail restrictions are not applicable, genoas of 200% overlap can be found, although those over 150% are not often seen, since the additional area is shadowed by the mainsail when close hauled and generates diminishing returns in terms of power per actual sail area.The gennaker
The gennakerGennaker
A gennaker is a sail that was developed around 1990. Used when sailing downwind, it is a cross between a genoa and a spinnaker. It is asymmetric like a genoa, but the gennaker is not attached to the forestay like a jib or genoa. The gennaker is rigged like a spinnaker but the tack is fastened to...
has been around for several decades now, and as the name suggests it is a hybrid between a genoa and an asymmetrical spinnaker
Spinnaker
A spinnaker is a special type of sail that is designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of...
. A brand name of North Sails, the gennaker is a cruising sail based on the Code 0 spinnakers used on racing boats. Gennakers and similar code 0 variants offered by other makers are even larger than genoas (200% overlaps are not uncommon) and they have a much greater camber
Camber (aerodynamics)
Camber, in aeronautics and aeronautical engineering, is the asymmetry between the top and the bottom surfaces of an aerofoil. An aerofoil that is not cambered is called a symmetric aerofoil...
for generating larger amounts of lift when reaching
Points of sail
Points of sail describes a sailing boat's course in relation to the wind direction.There is a distinction between the port tack and the starboard tack. If the wind is coming from anywhere on the port side, the boat is on port tack. Likewise if the wind is coming from the starboard side, the boat...
. Flat cut gennakers can be effective for angles as low as 60–70 degrees. Spinnakers perform much better when running because the main sail blocks the wind of gennaker above 135–150 degrees.
History
The genoa jib was invented and first used by the famous Swedish sailor and shipowner Sven SalénSven Salén
Sven Gustaf Salén was a Swedish sailor who competed in the 1936 Summer Olympics and in the 1952 Summer Olympics...
(1890–1969) on his 6 m R-yacht "May-Be" in a regatta in Genova (Copa Tirreno). Salén capitalized on an opening in the rules allowing the foresail to be far more overlapping than the previous norm. He went on to win the Gold Cup in Oyster Bay later that year also using the overlapping jib. For many years afterwards the sail was known as the Salén jib, or the Swedish jib, as well as genoa, while the name genoa (genua) was used early on in the Swedish language. Salén also pioneered the like-sided spinnaker as well as the up/downhaul on the spinnaker pole.
The invention of the overlapping jib, that is also close to the deck to optimise airflow, is much older however and was rediscovered for yachting by Salén. This type of jib was in use for centuries by the fishermen in the Netherlands with their Botter type ships. The fishermen relied on the combination of a large jib while fishing so the mainsail could remain unused. After fishing the fisherman's jib helped to get the fish to markets fast.
A correct explanation of the interaction between jib and mainsail was published by aerodynamicist and yachtsman Arvel Gentry in 1981, and "is much more complicated than the old theories imply". This states that the widely believed explanation of the slot effect is "completely wrong" and shows that this is not due to the venturi effect
Venturi effect
The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. The Venturi effect is named after Giovanni Battista Venturi , an Italian physicist.-Background:...
(or "valve effect" to use Curry's term) accelerating the air in the slot. Instead it is shown that the air in the slot is slowed down and its pressure increased reducing the tendency of the mainsail to stall, that the mainsail reduces the air pressure on the lee side of the jib accelerating that airflow, and that the mainsail increases the angle at which the air meets the luff of the jib, allowing the boat to point higher. Gentry points out that proper understanding of sail interaction allows better sail trimming.
Sven Salen's crew on the 6 meter was another Swede by the name of Gunnar Jacobson who worked as an architectural designer in Los Angeles until his death.