Mast, boom and fittings

The mast is the vertical aluminum, carbon or wooden spar carrying the sails and rig loads; the boom supports the foot of the mainsail. A deck-stepped mast stands on a deck compression structure, while a keel-stepped mast passes through the deck at the partners and rests on a step low in the hull. Spreaders project sideways and hold shrouds away from the mast. Their inboard attachment is the spreader root; the outer end is the spreader tip. The gooseneck joins boom to mast. A masthead sheave is a pulley at the mast top over which a halyard runs. Tangs, sheave pins, exit plates, winch pads and boom-vang fittings transfer concentrated loads into the spar.

An in-mast furling mast also contains a rotating luff extrusion, bearings and a geared furling unit. Its vertical slot is where the sail enters; it is not damage simply because it is open. The sail is rolled continuously, so there are no fixed slab-reef cringles or separate reefing lines.

A cracked spreader root, corroded mast step or failed gooseneck can disable the sail plan even when the standing rigging is new. Failure of the spar or a primary attachment can cause dismasting. Worn sheaves cut expensive halyards; a seized in-mast system can trap too much sail out in rising wind. The Pacific itinerary also subjects painted and anodized aluminum to salt, stainless fasteners and tropical moisture—the ingredients for hidden galvanic corrosion.

Service includes washing, lubricating manufacturer-specified furling bearings, clearing drains, replacing sheaves and pins, tightening/isolating fasteners and renewing gooseneck or vang bushings. Local corrosion may be cleaned, measured and protected; a rigger or spar builder must judge any material loss near a highly loaded fitting. Cracked welds or castings are replaced or professionally engineered, not covered with sealant.

Painting is cosmetic protection unless corrosion treatment is included. Replacing a complete mast is the last resort for a bent extrusion, major crack, unavailable structural fittings, pervasive corrosion or an uneconomic furling rebuild. Changing from in-mast furling to slab reefing is a redesign involving mast/track, sail, boom hardware and running rigging, not a routine spar service.

• Covered by a standard survey — deck-visible corrosion, mast alignment, obvious dents, accessible step/partners, boom and gooseneck play, basic operation of the furling system and visible fittings. Some surveyors inspect only from deck.
• Not covered — close aloft examination, removing fasteners, measuring extrusion wall loss, dismantling an in-mast furler, inspecting a keel-step hidden under trim or dropping the mast. A rigger visit ($600–$1,500) is sensible before purchase if there are corrosion bubbles, a damaged spreader, difficult furling or unexplained mast work; mast removal is normally post-purchase unless a major defect is suspected.

• The broker or owner — “Please send invoices for mast unstepping, spar inspection, painting, furling service, sheaves, gooseneck or spreader repairs.” “Has the mast ever been bent, grounded under a bridge, struck by lightning or had water collect at the step?” “Please identify the mast and furler manufacturer/model and provide its manual.”
• The surveyor — “Inspect the mast step and compression structure, partners, spreader roots/tips, gooseneck and vang attachments. Operate the furling main under load if possible and identify corrosion that needs a mast-down assessment.”

Walk around the mast looking for bulges, dents, cracks, white aluminum powder, blistered paint around stainless fittings and rivets pulling through. At the base, check for standing water, crushed deck, rusty compression-post fasteners and a step that has sunk. Shake the boom vertically and sideways; modest joint play may be a bushing, large movement or elongated holes cost more. Run each halyard slowly and listen for rough or frozen sheaves. With an in-mast main, unfurl and refurl at the dock: uneven roll, extreme winch load, scraping, torn luff tape or sail creases are evidence, not “normal for furling.”