Taking on water: locate, plug, alert

Faced with water coming in, the right sequence is three verbs: locate the leak — a seacock, a stern gland or a hose in the vast majority of cases —, plug it with whatever the boat carries, and alert your coastguard or rescue centre on VHF channel 16 as soon as the situation is not fully under control. Bilge pumps only buy time: no pleasure-boat pump can keep up with a clean hole below the waterline.

Where the water gets in: the usual suspects

Most leaks do not come from a collision but from a fitting that passes through the hull. Before you think of rocks, think of plumbing:

• seacocks and their valves (marine toilet, sinks, engine raw-water intake): corrosion, a seized valve, a tired fitting;
• the propeller shaft's stern gland: a slow drip can be normal, a steady trickle never is;
• hoses and their clamps, especially single-clamped runs below the waterline;
• the sail-drive diaphragm, due for replacement roughly every seven years;
• log and depth transducers, poorly re-seated after a haul-out.

Impacts — floating debris, a shoal, a botched grounding — are rarer but more brutal: the bow sections, the keel or centreboard case and the rudder then become the first places to check. A cruising boat commonly has five to fifteen through-hulls below the waterline: knowing them before the incident changes everything, because hunting for a hole under dark, oily bilge water is far harder than most people imagine.

Finding it fast: a simple method

First data point: taste the water. Fresh means a tank, the water heater or rain; salt means the sea, and the clock is running. Then work upstream: lift the floorboards, spot the direction of the flow, and check the through-hulls one by one, bow to stern. Two moves speed up the search: slow down or stop, because some leaks only flow under way (stern gland, stern tube, rudder stock); and tack if you are sailing, since heel can immerse or expose the leak. If the engine is running, glance at the raw-water circuit too: a blown hose can fill a bilge in minutes.

Plugging with what you have aboard

The goal is not a tidy repair: it is cutting the flow enough for the pumps to regain the advantage.

• If the leak comes from a valve or a hose, close the seacock: the most effective move, and the most forgotten under stress.
• Soft wooden bungs, lashed permanently next to each seacock, hammer into a torn-out fitting.
• Rubber cones and emergency sealing putty are useful additions to the modern kit.
• A cushion or cloth pressed home by a board and a tensioned line makes an excellent patch over a hull breach.
• On a split hose: self-amalgamating tape, a second clamp, a cable tie as a stopgap.

Pumps: buying time, not winning the war

Numbers keep things honest. An electric bilge pump claims 40 to 100 litres per minute on paper — often half that in real conditions, between head height, hose bends and a clogged strainer. Against that, a 3-centimetre hole 50 centimetres below the waterline lets in several hundred litres per minute. The honest conclusion: pumps are for drying out after plugging and for slowing the rise while you search, not for saving a holed boat. A bucket in the hands of a motivated crew member remains a surprisingly serious dewatering device — provided you actually carry a solid bucket.

Alerting: PAN PAN early, MAYDAY without hesitation

The right reflex is to call early. Put out a PAN PAN to your rescue centre on channel 16 as soon as a leak is detected, even if it seems contained: the services open a file, get assets ready, and cancelling costs nothing. If the water keeps rising despite plugs and pumps, switch to MAYDAY without second thoughts: get lifejackets on, prepare the grab bag, the liferaft and a fresh position. The detailed call procedure, distress beacons and who does what are covered in our guide Coastguard, MRCC, MAYDAY: who to call and how.

Where to start: prepare the boat today

A leak is 80% managed before it ever happens:

• map every through-hull with your crew, laminated diagram posted by the chart table;
• lash a correctly sized bung next to each seacock;
• work every valve several times a season to prevent seizing;
• actually test your pumps, float switch included, with a bucket of water poured into the bilge;
• make the stern gland, anodes and hoses a fixed item of the annual haul-out.

Finally, check that your safety equipment is complete and reachable, and keep the boat's vocabulary fresh with the glossary: under stress, being able to name a seacock to a crew member saves precious seconds.