Take It Easy
From The Dockline, May, 1997
Although the general principles of rigging and sail tensioning hold for all classes of boats this article is intended specifically for the Soling One Meter Class. It has been my observation that some skippers are prone to tension their sails and standing rigging much too tightly and as a result boat performance suffers greatly. Additionally, this over tensioning can result in mechanical damage to the boat and permanent deformation of the hull and or sails. What follows is a common sense approach to dealing with these problems.
Standing rigging consists of the various stays and shrouds used to maintain the mast in an erect position. When standing rigging is set too tight it can impose excessive loads upon the mast, deck, hull, and fittings. With the exception of the jib-stay, tensioning of various parts of the standing rigging should be such that they are slightly tighter than the amount necessary to remove any visible slack in the affected part. Correct tensioning of diamond stays (which keep the mast in a straight-line athwartship) is achieved when the mast cannot be caused to bend with a moderate sideways pressure on the head of the mast. A very slight bend under heavy pressure is acceptable. Diamond stay adjustments for both tensioning and mast straightness are normally made by varying the effective length of each spreader, however, some boats may use a turnbuckle arrangement on one or both stays.
Shrouds are used to support the mast and keep it vertical athwartship. Shroud tensioning is normally accomplished by adjusting the mast jackscrew, but may also be accomplished using individual adjustments on each shroud. Tension is correct when medium sideways pressure at the spreader results in the opposite shroud just beginning to show signs of slackening. Care must be taken to keep the mast vertical athwartships especially when using individual adjustments.
The jibstay keeps the mast from failing backward, supports the luff of the jib, tensions the jib leech, and by its length sets the rake of the mast. Jibstay tension is controlled by the tension of the backstay (used to keep the mast from falling forward). When setting backstay tension the luff of the jib sail should be slackened to permit the jibstay to take the fill load. The final setting of backstay tension is dependent upon existing wind strength. Very slightly eased in light winds, and tighter in high winds (a good approximation or starting point for setting the backstay tension is reached when pressing forward on the masthead causes the forestay to slacken slightly but not become floppy).
After backstay tension has been set the jib luff should he tensioned to remove any horizontal wrinkling or slackness of sail material along the luff. If vertical wrinkles appear on the jib just behind the luff then you have over-tightened the luff. There is a small amount of luff adjustment available between the disappearance of horizontal wrinkles and the appearance of vertical wrinkling, this may be used in "tweaking" or tuning the boat. Normally the load should be carried by the jibstay rather than the jib luff and on occasion it may be carried equally, but the load should never he allowed to be carried by the luff alone (i.e.: jibstay slack within the doubled luff). Jib twist is controlled by very minute changes in backstay tension.
Adjustment of the mainsail luff is similar to that of the jib luff (somewhere between the disappearance of any slackness or horizontal wrinkling and the appearance of vertical wrinkles). Mainsail twist is controlled by the boom vang. When sailing close hauled the downward force of the main- sheet can control twist, but when off the wind mainsail twist is controlled by the vang alone. The vang should be adjusted to give the desired amount of twist when the boom is at its maximum outboard position. Often in very high winds it is desirable to intentionally induce more twist to "unload" the head of the sail in order to reduce heeling, but this technique should be used with caution since on occasion too much twist can induce a high degree of roll when on a run.
Excessive tensioning of sails in an attempt to flatten them for sailing in high wind conditions can cause permanent deformation of the sail material, particularly along the foot of the sail. Sail camber (a measure of the degree of curvature) is determined by the clew outhaul. The absolute minimum camber used should allow one finger to be easily inserted between the foot of a sail and its boom, and this only when sailing in the highest of winds. Normal camber settings range from about a finger-and-a-half to two-fingers easily inserted between the foot of a sail and its boom.
Unless you dismount your rig for transportation and storage maintain the rig tension during transportation to and from the pond since a loose rig will be subject to shock loads as it bounces in response to vehicle jostling. While the boat is in storage rigging and sail tensions should be eased to prevent any deformations which may arise from constant pressure over a long period. Sails are the most fragile piece of equipment and should be handled with great care if they are to perform properly and have a long life. Two of the greatest enemies of model sails are improper storage and being allowed to luff violently for extended periods. Any creasing or distortion (as may occur if sail material is permitted to lie against sharp or angular surfaces, or as a result of over tensioning) will be permanent and will interfere with smooth airflow across the surfaces of the sail resulting in decreased performance. Violent luffing will “soften" sail material by causing resinated surfaces to break down which will, in turn, allow the weave of the cloth to distort and lessen the ability of the material to hold its designed shape, In both cases the useful life of the sail is greatly shortened. (Sail material of the non-woven type such as Mylar laminated materials can also be distorted and may undergo delamination by improper storage and/or violent luffing.) Strange as it may seem, most sail damage usually occurs when transporting the rig between the vehicle and the race site or home storage. It is during this interval that the rig is being carried in a more or less fixed position and not allowed to streamline in the ambient wind. As a consequence the sails can flop about and often come up hard against foreign objects or may double over creating creases. Additional damage can occur by the rig getting caught in overhanging branches or doorways. A little care in transporting sails and storing sails can go a long way towards keeping you "engine" in good condition. Remember, take it easy!
Although the general principles of rigging and sail tensioning hold for all classes of boats this article is intended specifically for the Soling One Meter Class. It has been my observation that some skippers are prone to tension their sails and standing rigging much too tightly and as a result boat performance suffers greatly. Additionally, this over tensioning can result in mechanical damage to the boat and permanent deformation of the hull and or sails. What follows is a common sense approach to dealing with these problems.
Standing rigging consists of the various stays and shrouds used to maintain the mast in an erect position. When standing rigging is set too tight it can impose excessive loads upon the mast, deck, hull, and fittings. With the exception of the jib-stay, tensioning of various parts of the standing rigging should be such that they are slightly tighter than the amount necessary to remove any visible slack in the affected part. Correct tensioning of diamond stays (which keep the mast in a straight-line athwartship) is achieved when the mast cannot be caused to bend with a moderate sideways pressure on the head of the mast. A very slight bend under heavy pressure is acceptable. Diamond stay adjustments for both tensioning and mast straightness are normally made by varying the effective length of each spreader, however, some boats may use a turnbuckle arrangement on one or both stays.
Shrouds are used to support the mast and keep it vertical athwartship. Shroud tensioning is normally accomplished by adjusting the mast jackscrew, but may also be accomplished using individual adjustments on each shroud. Tension is correct when medium sideways pressure at the spreader results in the opposite shroud just beginning to show signs of slackening. Care must be taken to keep the mast vertical athwartships especially when using individual adjustments.
The jibstay keeps the mast from failing backward, supports the luff of the jib, tensions the jib leech, and by its length sets the rake of the mast. Jibstay tension is controlled by the tension of the backstay (used to keep the mast from falling forward). When setting backstay tension the luff of the jib sail should be slackened to permit the jibstay to take the fill load. The final setting of backstay tension is dependent upon existing wind strength. Very slightly eased in light winds, and tighter in high winds (a good approximation or starting point for setting the backstay tension is reached when pressing forward on the masthead causes the forestay to slacken slightly but not become floppy).
After backstay tension has been set the jib luff should he tensioned to remove any horizontal wrinkling or slackness of sail material along the luff. If vertical wrinkles appear on the jib just behind the luff then you have over-tightened the luff. There is a small amount of luff adjustment available between the disappearance of horizontal wrinkles and the appearance of vertical wrinkling, this may be used in "tweaking" or tuning the boat. Normally the load should be carried by the jibstay rather than the jib luff and on occasion it may be carried equally, but the load should never he allowed to be carried by the luff alone (i.e.: jibstay slack within the doubled luff). Jib twist is controlled by very minute changes in backstay tension.
Adjustment of the mainsail luff is similar to that of the jib luff (somewhere between the disappearance of any slackness or horizontal wrinkling and the appearance of vertical wrinkles). Mainsail twist is controlled by the boom vang. When sailing close hauled the downward force of the main- sheet can control twist, but when off the wind mainsail twist is controlled by the vang alone. The vang should be adjusted to give the desired amount of twist when the boom is at its maximum outboard position. Often in very high winds it is desirable to intentionally induce more twist to "unload" the head of the sail in order to reduce heeling, but this technique should be used with caution since on occasion too much twist can induce a high degree of roll when on a run.
Excessive tensioning of sails in an attempt to flatten them for sailing in high wind conditions can cause permanent deformation of the sail material, particularly along the foot of the sail. Sail camber (a measure of the degree of curvature) is determined by the clew outhaul. The absolute minimum camber used should allow one finger to be easily inserted between the foot of a sail and its boom, and this only when sailing in the highest of winds. Normal camber settings range from about a finger-and-a-half to two-fingers easily inserted between the foot of a sail and its boom.
Unless you dismount your rig for transportation and storage maintain the rig tension during transportation to and from the pond since a loose rig will be subject to shock loads as it bounces in response to vehicle jostling. While the boat is in storage rigging and sail tensions should be eased to prevent any deformations which may arise from constant pressure over a long period. Sails are the most fragile piece of equipment and should be handled with great care if they are to perform properly and have a long life. Two of the greatest enemies of model sails are improper storage and being allowed to luff violently for extended periods. Any creasing or distortion (as may occur if sail material is permitted to lie against sharp or angular surfaces, or as a result of over tensioning) will be permanent and will interfere with smooth airflow across the surfaces of the sail resulting in decreased performance. Violent luffing will “soften" sail material by causing resinated surfaces to break down which will, in turn, allow the weave of the cloth to distort and lessen the ability of the material to hold its designed shape, In both cases the useful life of the sail is greatly shortened. (Sail material of the non-woven type such as Mylar laminated materials can also be distorted and may undergo delamination by improper storage and/or violent luffing.) Strange as it may seem, most sail damage usually occurs when transporting the rig between the vehicle and the race site or home storage. It is during this interval that the rig is being carried in a more or less fixed position and not allowed to streamline in the ambient wind. As a consequence the sails can flop about and often come up hard against foreign objects or may double over creating creases. Additional damage can occur by the rig getting caught in overhanging branches or doorways. A little care in transporting sails and storing sails can go a long way towards keeping you "engine" in good condition. Remember, take it easy!