1. Start with the system actually installed
A slab-reefing mainsail, an in-mast furling mainsail and an in-boom furling mainsail require different procedures. Seldén documentation distinguishes the mechanisms and their operating methods: an instruction that applies to one model does not automatically apply to another.
Make a reference sheet identifying the boom, reefing-line routes, tack and clew attachments, and permitted adjustments. Draw the rope path instead of relying only on line colours. Where an older alteration has no documentation, have the arrangement checked before including it in your procedure. Keep the exact manual available offline rather than a generic illustration found online.
References for this section : Seldén — Assembly and operation manuals
2. Decide before conditions force it
Reefing reduces exposed sail area. The North Sails guide also stresses the resulting shape: the reef clew needs restraint both downwards and aft. Simply making the sail smaller without controlling its tension is therefore not the whole task.
Write down decision criteria using the boat’s manual: expected gusts, sea state, point of sail, visibility, crew capability and room to manoeuvre. A single wind speed would imply false precision. On a catamaran, do not interpret the absence of pronounced heel as proof that the sail plan is safe; use the builder’s limits and instructions for the actual boat.
References for this section : North Sails — How to reef a mainsail
3. Assess balance before fine tuning
Trim depends on sea state and point of sail as well as wind strength. North Sails’ cruising guide considers draft, angle of attack and twist together: one sail shape cannot suit every situation.
During a practice sail, record behaviour before and after just one adjustment: helm load, course keeping, flogging, speed and comfort. The autopilot is not a safety measuring instrument for the sail plan. If it makes repeated corrections, reconsider the whole arrangement instead of asking it to work harder. Note observations separately from conclusions so you can discuss them usefully with a sailmaker or instructor.
References for this section : North Sails — Cruising sail trim
4. Rehearse a boat-specific sequence
The preparation below is a working method to validate aboard, not a universal reefing sequence. Decide who maintains the lookout and control of the boat, who handles the lines and who watches the sail. Agree on a stop command everyone understands.
At the berth, identify each control without loading the rig. In calm water, practise the manufacturer’s procedure with a competent person, then record the checkpoints. Marks on a halyard help repeatability, but do not prove that the tack is secured, the reefing line runs freely or the sail is carrying its loads correctly. Check the actual result, not only the marks.
References for this section : Seldén — Assembly and operation manuals
5. Furler and winch: stop at an obstruction
The cited Seldén manual calls for controlled outhaul tension while furling and specifies system-dependent locking positions. It also warns against leaving a handle in its furling mechanism. These instructions apply to the models identified in that manual.
An unfamiliar resistance means stopping, finding the cause and following the manufacturer’s troubleshooting procedure. Before using a powered winch, identify its stop control and the person watching the working area. Available power never justifies pulling blindly against an obstruction. Use the installed winch’s manual for its operating limits; do not borrow settings from a larger or superficially similar unit.
References for this section : Seldén — Manual for furling mast type RB/RC, 595-020-E · Harken — Rewind winch user manual
6. Inspect the areas that carry and rub
North Sails advises checking for chafe and protecting contact areas around rigging and equipment. Inspect a sail as a combination of fabric, stitching, reinforcement and fittings, rather than just a white surface.
Build a dated photographic record of reef points, webbing, rings, slides and spreader-contact areas. Repeat the same views after a passage. Describe a defect by location and change over time; “still fine” gives a sail loft little useful information. Opening stitching or distorted reinforcement merits assessment before the next substantial loading. Keep repair instructions alongside the record so the next inspection checks the repaired area deliberately.
References for this section : North Sails — Sail care & maintenance tips
7. Build the boat’s manoeuvre card
A useful card fits on one page: identified configuration, operating conditions, allocated roles, validated steps, checks after reefing and the planned response if the sail will not lower or furl. Add the version of the manual used and any onboard modifications.
A suggested report might read: “Daylight trial, full crew, first reef set; one line rubs at the boom exit; correct before departure.” That record is more useful than copying a wind threshold from another boat. Repeat the exercise after changing sails, ropes or rigging, so a familiar but outdated procedure does not become accepted merely through habit.
References for this section : Seldén — Assembly and operation manuals
Anticipate, follow the actual installation and stop at unexpected resistance: a rehearsed procedure is more useful than a universal wind number.
Your practical checklist
Sources & documents
- North Sails — How to reef a mainsail
Accessed 2026-11-02 - North Sails — Cruising sail trim
Accessed 2026-11-02 - North Sails — Sail care & maintenance tips
Accessed 2026-11-02 - Seldén — Manual for furling mast type RB/RC, 595-020-E
Accessed 2026-11-02 - Seldén — Assembly and operation manuals
Accessed 2026-11-02 - Harken — Rewind winch user manual
Accessed 2026-11-02
