Harken 7413.15 MKIV Hydraulic Jib Reefing & Furling - Manual (Page 28)

28 MKIV Hydraulic Unit 3
Commissioning Halyard: Restrainer/Tension
To prevent wraps, jib halyard must pull slightly to rear. On most boats,
halyard lead angle is acceptable if halyard swivel is raised to top of foil.
On some boats halyard sheaves are located too close to headstay and
a halyard restrainer must be used.
Halyard restrainers should be used only when required by masthead
geometry. Restrainers tend to limit sail luff length and may cause
problems if not installed properly.
If your boat needs a halyard restrainer, use Harken Part No. 945 or 1988.
Restrainer should be mounted as high as possible on face of mast.
Position restrainer so that foils will not hit it when under load.
The restrainer should deflect halyard as little as possible or you may
experience difficulty in tensioning sail luff, friction when furling, and
possible damage to foils. To decrease deflection angles, shorten sail luff.
Tip: Boats used in charter service should have a halyard restrainer,
regardless of masthead geometry.
Halyard Tension
The jib halyard should be firm, but not too tight.
Tip: The luff foil system supports sail along its length so halyard
tension is used only to shape sails, not to support them. Use enough
halyard tension to remove some wrinkles along luff of sail. Do not
tension halyard enough to cause vertical wrinkles in luff of sail.
Tension to adjust position of draft in sail to suit sailing conditions.
Halyard should be firm but not tight. If in doubt, release halyard
tension. To protect sail, ease halyard when boat is not in use.