3.6 Flooding, Damage Control & Abandon Ship

Flooding Is a Race Against Free Surface

On Q161 Deck Safety, flooding scenarios test whether you can find the source, isolate it, pump, and decide whether the vessel remains a safe refuge. On a Master 100 platform the same sequence is command doctrine: progressive flooding plus free surface can destroy stability long before the deck edge submerges. Act early, talk clearly to the crew, and keep passengers from blocking pumps, hatches, and exits.

Locate and Isolate

When high bilge alarms sound, water appears in a compartment, or a collision/grounding is felt:

1. Sound the alarm and station the crew for damage control / emergency stations.
2. Find the source — open seacock, failed hose, stuffing box, hull breach, cracked through-hull, ruptured tank, open hatch shipping seas.
3. Isolate — close watertight doors, hatches, and valves; secure the seacock if that is the path; shut off systems feeding the leak when safe.
4. Start pumps — fixed bilge pumps, portable pumps, and bucket brigades as capacity allows. Clear rose boxes/strainers so pumps actually move water.
5. Reduce free surface — dewater decks and bilges aggressively; do not leave ponded water high in the hull.

Isolation buys time. A small hole open to the sea with a closed compartment and running pumps is often survivable; the same hole with every door dogged open is a sinking.

Pumps and Capacity Reality

Know what your vessel actually has:

• Electric bilge pumps and float switches (primary for routine water)
• Engine-driven or high-capacity emergency pumps if fitted
• Portable dewatering pumps (common damage-control asset)
• Manual pumps and human chain as last layer

If inflow exceeds pump capacity, temporary plugging must reduce the hole, or you must beach / ground intentionally or abandon. Hoping the bilge pump will catch a collision hole without damage control is how vessels are lost.

Temporary Repairs: Mats, Plugs, Patches, Shores

Classic damage-control tools still appear on captain exams:

Technique principles:

• Slow the leak enough for pumps to gain — perfection is secondary to dewatering progress.
• Work from safety: life jackets for crew at the rail, lines on people over the side, engines/prop secured if divers or swimmers work near the hull.
• After a collision, check all compartments, not only the obvious dent — progressive flooding kills.

Grounding and Beaching Precautions

Intentional beaching (or remaining hard aground in a controlled way) can keep a flooded hull from sinking in deep water so passengers can walk or wade to safety or await rescue high and dry. Exam and operational cautions:

• Prefer a gently sloping, soft bottom (sand/mud) over rock when you have a choice.
• Know the tide — beaching on a falling tide can leave you high and dry for hours; a rising tide may refloat a damaged hull before you are ready.
• Approach slowly, bow-on or as hull form and damage dictate; avoid ripping the only remaining intact bottom.
• Once aground, continue damage control, account for persons, and prepare for refloat or abandon as conditions change.
• Accidental grounding after collision: sound compartments, check for oil pollution, and do not power off violently if that will worsen the breach.

When to Abandon Ship

Abandon ship when the vessel is no longer a safer place than the survival craft or the water with flotation — typically uncontrolled fire, flooding beyond pump and patch capacity, capsize risk, toxic atmosphere, or structural failure. The master gives the order; crew do not freelancely abandon while the vessel is still viable.

Prepare early even if you hope to save the ship:

• Don PFDs (passengers and crew)
• Ready liferafts, buoyant apparatus, and survival craft
• Transmit distress (Mayday, DSC, EPIRB as fitted) while power and antennas still work
• Grab the grab bag / emergency kit (VHF handheld, flares, first aid, water, signaling gear, vessel papers if time)
• Muster and headcount at embarkation stations

Abandon Ship Procedures

On the order to abandon:

1. Mayday (if not already complete) with position, nature of distress, number of persons, and intentions.
2. Launch or release survival craft per vessel arrangement — painter secured correctly, painter length and hydrostatic releases understood on inspected craft.
3. Board survival craft dry if possible; assist elderly, children, and non-swimmers first as the situation allows.
4. Clear the vessel when it is dangerous (suction, fire, rolling superstructure).
5. Account for everyone; search only if it does not needlessly sacrifice remaining lives.
6. Stay near the scene when safe (searchers look where the vessel was) unless fire, breaking seas, or lee shore demand distance.
7. Activate EPIRB/PLB, use pyrotechnics when a rescuer can see them, and conserve water and morale.

Rescue of Survivors (Ship or Aircraft)

Recovering people from the water, a liferaft, or wreckage (including aircraft ditching survivors near your vessel):

• Approach from a direction that does not put survivors under the bow or prop.
• Use heaving lines, life rings, ladders, and scramble nets; stop engines or keep prop clear when people are alongside.
• Treat for hypothermia and shock; keep survivors horizontal when spinal injury is possible and move carefully.
• For aircraft survivors, watch for fuel on the water (fire risk) and sharp wreckage.
• Report numbers recovered and missing to SAR authorities promptly.

Emergency Towing Basics

If another vessel can save yours or move you from a lee shore:

• Agree who is tow and who is towed, speed, and communications (VHF working channel).
• Use adequate towline with chafe protection; make fast to strong points (bitts, towing bitts — not random rails or stanchions).
• On the towed vessel: steer to reduce yaw if able, keep bilge pumps running, and be ready to slip the tow if the line endangers either crew.
• On passenger vessels, brief passengers to stay seated and clear of the towline snap-back zone.
• A tow is not a substitute for distress communications if people remain at risk.

Master’s flooding decision ladder

Find → isolate → pump → patch → reassess stability and freeboard → beach if that saves lives → abandon only when the ship is the greater danger. That ladder is what Q161 is probing when stems mention collision mats, rose boxes, and the order to take to the boats.