Lee Helm
Encyclopedia
Lee Helm is the tendency of a sailboat to turn away from the wind while under sail. It is the opposite of Weather helm
which is the tendency of a sailboat to "round up" into the wind. A boat with lee helm will be difficult to sail Close Hauled and tacking
may be difficult.
, perhaps repeatedly. In an uncontrolled jibe the force of the wind moves the sails
and boom
from one side of the boat to the other. In a strong wind this movement will by very fast and forceful and can damage the boat, the sails, injure the crew, and even cause the boat to Broach
(lie over on its side).
The root cause of lee helm is when the center of pressure exerted by the wind on the sails falls too far forward of the center of resistance of the hull—the natural point at which the hull tries to pivot. This tends to push the bow of the boat away from the wind. This can be due to a poor design, for example with the mast too far forward.
A small amount of lee helm can be counteracted with the rudder, but this introduces significant drag in the water and slows the boat. A small amount of lee helm can also be cured by raking the mast backward, reducing the size of the Jib
on a Sloop
rigged boat, or increasing the size of the mizzen sail on a Yawl
or a Ketch
. Large amounts of lee helm can only be corrected by altering the placement of the mast(s) or keel
/centerboard
--- a non-trivial venture.
Weather helm
Weather helm is the tendency of sailing vessels to turn towards the source of wind, creating an unbalanced helm that requires pulling the tiller to windward in order to counteract the effect. Weather helm is the opposite of Lee Helm....
which is the tendency of a sailboat to "round up" into the wind. A boat with lee helm will be difficult to sail Close Hauled and tacking
Tack (sailing)
Tack is a term used in sailing that has different meanings in different contexts, variously a part of a sail, and an alignment with the wind. When using the latter sense, the maneuver of turning between starboard and port tack is either tacking or jibing....
may be difficult.
Description
Lee helm is considered dangerous in a sailboat. While sailing, if left to its own devices a boat with lee helm will bear (turn) away from the wind, accelerate, and perform an accidental or uncontrolled jibeJibe
A jibe or gybe is a sailing maneuver where a sailing vessel turns its stern through the wind, such that the wind direction changes from one side of the boat to the other...
, perhaps repeatedly. In an uncontrolled jibe the force of the wind moves the sails
Sail
A sail is any type of surface intended to move a vessel, vehicle or rotor by being placed in a wind—in essence a propulsion wing. Sails are used in sailing.-History of sails:...
and boom
Boom
-Pole or spar application:* Boom , spar at the foot of a sail on a sailboat* Boom , a wishbone shaped piece of windsurfing equipment* Boom barrier, a barrier used to block vehicular access through a controlled point...
from one side of the boat to the other. In a strong wind this movement will by very fast and forceful and can damage the boat, the sails, injure the crew, and even cause the boat to Broach
Broach (sailing)
A sailboat broaches when its heading suddenly changes towards the wind due to wind/sail interactions for which the rudder cannot compensate. This causes the boat to roll dangerously and if not controlled may lead to a capsize...
(lie over on its side).
The root cause of lee helm is when the center of pressure exerted by the wind on the sails falls too far forward of the center of resistance of the hull—the natural point at which the hull tries to pivot. This tends to push the bow of the boat away from the wind. This can be due to a poor design, for example with the mast too far forward.
A small amount of lee helm can be counteracted with the rudder, but this introduces significant drag in the water and slows the boat. A small amount of lee helm can also be cured by raking the mast backward, reducing the size of the 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...
on a 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....
rigged boat, or increasing the size of the mizzen sail on a 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...
or a 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...
. Large amounts of lee helm can only be corrected by altering the placement of the mast(s) or keel
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
/centerboard
Centreboard
A centreboard or centerboard is a retractable keel which pivots out of a slot in the hull of a sailboat, known as a centreboard trunk or centerboard case...
--- a non-trivial venture.