12.3 Heavy Weather Seamanship, Stability & Man Overboard Recovery

12.3 Heavy Weather Seamanship, Stability & Man Overboard Recovery

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Heavy Weather Preparation & Seamanship Tactics

The golden rule of heavy weather sailing is to prepare before the storm strikes. Once overwhelmed by gale-force winds and breaking seas, deck work becomes hazardous and exhausting.

Vessel Preparation & Husbandry

• Early Sail Reduction: Reef early. An upright yacht makes faster progress, reduces rig strain, and preserves helm control.
• Storm Sails: Shift to a dedicated storm jib on a removable inner stay. Rig a storm trysail on a dedicated mast track with separate sheets, bypassing the boom.
• Deck Security: Rig flat webbing jackstays along side decks from cockpit to foredeck. Lock down deck hatches and vents. Fit companionway washboards and engage retaining bolts so washboards cannot float out if pooped.
• Watertight Integrity: Close non-essential seacocks (heads, sinks) to prevent back-siphonage. Verify automatic and manual bilge pumps.

Tactics for Survival in Breaking Seas

1. Heaving-To:
   • Procedure: Back the headsail, ease and adjust the main, and set the rudder to turn the bow towards the wind: tiller to leeward or wheel to windward. Secure the control after the yacht settles.
   • Hydrodynamics: Opposing forces balance, typically holding the yacht around 45° to 60° off the wind with slow leeward drift. The balance and drift depend on the yacht and conditions.
   • The Slick: As the yacht drifts downwind, hull and keel shed a turbulent wake to windward called a slick, absorbing wave energy and breaking crests before they strike the hull.
2. Running Off Before the Sea:
   • Sailing downwind under bare poles or storm jib, actively steering perpendicular to overtaking crests.
   • Broaching & Pitchpoling: A following crest can lift the stern and bury the bow, causing the yacht to slew broadside (broaching) and potentially onto its beam ends. In steep breakers, the stern is lifted vertically, somersaulting the vessel end-over-end (pitchpole).
3. Trailing Warps & Drogues:
   • Trailing Warps: Streaming long bights of heavy line astern creates drag to reduce surfing. The required arrangement depends on the yacht and conditions.
   • Series Drogue (Jordan Series Drogue): Multiple small cones on a line deployed from a stern bridle reduce drift and help keep the stern towards breaking seas. Use a system sized for the yacht, with suitable strong points, chafe protection and the specified deployment arrangement.

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Fire Prevention and Initial Response

Fire needs heat, fuel and oxygen. Maintain fuel, gas and electrical systems, secure flammable liquids in suitable ventilated stowage, and keep escape routes clear. Brief everyone on alarms, shut-offs, extinguishers and the fire blanket.

Raise the alarm, account for the crew and call for assistance. Tackle only a small fire that you can approach safely while retaining an escape route. Isolate fuel or electricity if safe. Use an extinguisher rated for the burning material: water suits ordinary solids, but must not be used on burning fuel, cooking oil or live electrical equipment. A fire blanket can smother a small galley-pan fire. Keep an engine-space fire enclosed and use its fitted extinguishing arrangement; opening the cover supplies oxygen. If the fire cannot be controlled safely, prepare to abandon and transmit distress.

Source: RYA fire safety on boats.

Yacht Stability Dynamics, GZ Curves & STIX Ratings

The Curve of Statical Stability (GZ Curve)

The Curve of Statical Stability plots vessel Righting Lever (GZ) against Heel Angle:

• Righting Lever (GZ): Horizontal separation between vertical lines of gravity (acting through G) and buoyancy (acting through B) when heeled.
• Righting Moment: Torque returning the yacht upright: displacement weight × GZ. Weight in kN multiplied by GZ in metres gives kNm.

Key Hydrostatic Thresholds on the GZ Curve

1. Initial Stability: The small-angle slope of the GZ curve, affected by hull form and the centre of gravity.
2. Maximum Righting Lever (GZ_max): The peak of the curve; its heel angle depends on the vessel and loading condition.
3. Angle of Downflooding: Heel angle at which water can enter through an unprotected opening. It is separate from AVS and may limit the usable stability range earlier.
4. Angle of Vanishing Stability (AVS): Heel angle where GZ drops back to zero.
   • Between 0° and AVS, positive stability returns the vessel upright.
   • Beyond AVS, GZ becomes negative: gravity and buoyancy hold the vessel inverted.
   • Many offshore monohulls have an AVS above90°, giving a restoring moment after a90° knockdown in the intact-hull static model. Check the actual curve and downflooding limits.
   • Cruising catamarans rely on form stability, with maximum GZ at relatively small heel angles. Check the design’s own stability curve; an inverted cruising catamaran will not normally self-right.

ISO 12217, STIX Ratings & The Reality of Dynamic Stability

Under ISO 12217-2 (Small craft — Stability and buoyancy assessment and categorization), monohull sailing yachts are assessed using the Stability Index (STIX), a composite rating derived from length, dynamic stability, inversion and knock-down recovery, displacement-length and beam-displacement factors, wind moment, downflooding and reserve buoyancy:

• Category A: Winds may exceed Force8 and significant waves4m, excluding abnormal conditions such as violent storms and extreme/rogue seas. Sailing-yacht assessment requires STIX≥32 and displacement-dependent AVS criteria;100°–120° is not a universal qualifying range.
• Category B: Wind up to and including Force8 and significant waves up to4m; STIX≥23, with further stability criteria.
• Category C: Wind up to Force6 and significant waves up to2m. Category D: Wind up to Force4 and significant waves up to0.3m, with occasional waves up to0.5m. These categories specify conditions rather than permission to navigate a named area.

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Man Overboard (MOB): Immediate Initial Response

Cold shock can immediately disrupt breathing; subsequent muscle cooling reduces dexterity and swimming ability. Neither stage provides a safe waiting period: recover the casualty promptly. Execute the Four Initial Vital Actions concurrently:

1. SHOUT: Shout "MAN OVERBOARD" to alert helm and summon off-watch crew.
2. THROW: Immediately throw lifebuoy, Danbuoy (with flag/light), and recovery line into water toward casualty to mark datum.
3. PRESS: Activate the chartplotter’s MOB function using its prescribed control. It records the incident position; the casualty may drift away from that datum.
4. POST LOOK-OUT: Appoint a crew member whose sole duty is to point continuously at casualty without breaking visual contact.

Also send a DSC distress alert and MAYDAY promptly, while stopping or slowing the yacht and preparing recovery. Allocate these tasks among the available crew.

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MOB Recovery Maneuvers Under Sail and Power

1. The Quick Stop / Crash Stop (Under Sail)

Head up and tack without releasing the headsail sheet to slow the yacht and stay close. If using the engine, start in neutral and check that lines are clear before engaging gear. Make a controlled downwind circle and gybe, then approach on a close reach with speed reduced. Practise the manoeuvre on the actual yacht; there is no universal1–2boat-length turning circle.

2. The Williamson Turn (Power / Night / Fog)

Standard rescue turn at night, in fog, or when delayed:

1. Apply rudder hard over toward casualty side.
2. At 60° from original course, apply opposite rudder hard over.
3. Steady up on reciprocal course (180° from initial heading), returning along the original wake.

3. The Anderson Turn (Single Turn Under Power)

A 270° single-turn manoeuvre for an immediate, visible casualty: turn towards the casualty’s side, then amidships and initiate stopping after about250° heading change. It suits tight-turning powered vessels; allow for the actual boat’s handling and stopping distance.

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Casualty Retrieval & Hypothermia Management

Plan a slow, controlled approach, normally positioning the yacht upwind of the casualty so that it drifts towards them as it stops. Adapt to wind, sea and vessel handling. Alongside, keep the engine in neutral or switched off, as conditions require; prevent any turning propeller from reaching the casualty or recovery lines.

Casualty Extraction Posture & Hypothermia Pathophysiology

When recovering an immersion casualty alongside the vessel, careful consideration must be given to their extraction posture and hypothermia status:

Circum-Rescue Collapse & Extraction Priorities

An immersion casualty may deteriorate during or after rescue. Removing the water’s hydrostatic support can reduce venous return, and severe cooling increases cardiovascular vulnerability. Handle the casualty gently and support them horizontally or near-horizontally where practicable.

Useful methods include a parbuckle or boarding net, a recovery cradle supporting torso and legs, or a coordinated lift supporting the upper body and knees. Prepare and practise the system before an emergency.

Post-Recovery Assessment & Care

• Call for help and assess immediately: Check responsiveness and normal breathing; obtain Coastguard/medical assistance. Do not assume that an unconscious casualty only needs warming.
• Unresponsive and not breathing normally after drowning: Give 5 initial rescue breaths, then CPR, normally 30compressions to2breaths, and use an AED as soon as available. Dry the chest for its pads and follow its prompts. Continue until professional help takes over, normal breathing returns or you cannot continue.
• Unresponsive but breathing normally: Maintain an open airway and monitor continuously. Use the side-lying recovery position where appropriate; suspected trauma requires care, but airway protection remains essential. Follow emergency medical instructions.
• Conscious casualty: Keep them resting, supported and protected from cold; do not make a faint or severely cooled casualty stand or walk. Handle gently, remove wet clothing carefully, dry and insulate with blankets/survival bags, including beneath them, and shield them from wind and spray.
• Warming: Do not rub limbs or use intense direct heat. Body temperature can continue to fall after rescue (afterdrop). Give warm, sweet, non-alcoholic drinks only to someone fully alert and able to swallow safely. Reassess breathing and responsiveness while arranging medical review.

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Seamanship Traps & Examination Pitfalls

1. Static vs Dynamic Stability: An AVS of 130° or STIX rating ≥ 32 does not grant immunity from capsize in breaking seas.
2. MOB Response: Raise the alarm, throw flotation and a marker, mark the incident position and keep continuous visual contact. Practise these actions with the crew.
3. Propeller Safety: Forgetting to shift engine into neutral before coming alongside is a critical failure.
4. Extraction Priorities: Always aim for a horizontal lift where practicable to prevent circum-rescue collapse, but never delay water extraction if a horizontal rig cannot be promptly deployed.