Self-Sufficiency at Sea - Water, Provisioning & Power Budgets

Prerequisites

This is a Yachtmaster Ocean lesson. You should already:

• Hold the Yachtmaster Offshore Certificate of Competence (or MCA OOW Yachts <3000 gt), or be preparing for Ocean with that standard of experience.
• Be competent at Offshore-level passage planning, including fuel and water calculations for a passage of several days, and the routine engine checks (oil, coolant, belts, raw-water impeller, fuel filters) from the RYA Diesel Engine course.
• Understand a yacht's 12 V DC electrical system: batteries, charging sources, fuses and the basic amp-hour budget.
• Know standing and running rigging terminology and how to inspect it (Coastal/Offshore yacht preparation).

At Ocean level the examiner will question you on yacht preparation, maintenance and repairs and on victualling and bunkering. Your qualifying passage narrative must include these calculations and show how they worked out in practice.

Learning Objectives

By the end of this lesson you will be able to:

• Plan for a passage duration with an appropriate safety margin and understand how each resource runs down.
• Calculate water and food requirements for a crew and passage, and choose suitable provisions and storage.
• Explain how a reverse osmosis watermaker works and how to look after it, and plan alternative water sources.
• Design a resilient electrical system and power budget.
• Assemble and catalogue a spares inventory and tool kit for engine, rigging, electrical, steering and safety systems.
• Carry out a pre-departure rigging inspection and make emergency and permanent sail repairs at sea.
• Manage fuel quality, gas, refrigeration and other consumables, and plan emergency rationing if the passage overruns.
• Prepare psychologically for isolation and set up routines that sustain the crew.

RYA syllabus items covered (Yachtmaster Ocean, shore-based theory and the oral): yacht preparation, maintenance and repairs, and victualling and bunkering. In the exam you may be asked to calculate water, food and fuel for a stated crew and passage, to describe your spares and tool kit, to explain how you would handle an engine failure, a dismasting, a steering failure or a torn sail mid-ocean, and to justify the margins you chose. The qualifying ocean passage narrative must show these calculations and how they worked out in practice.

Why Self-Sufficiency Is Different Offshore

On a coastal passage, a broken impeller or a split sail is an inconvenience: you motor or sail into the nearest harbour. Halfway across an ocean, the nearest harbour may be 1,000 miles and 10 days away, and the nearest help may be a merchant ship that can take your crew off but not fix your boat. Mid-ocean, everything you need must already be on board, and you must be able to find it and use it. The skipper's preparation for this, which the RYA calls bunkering, victualling, spares and maintenance, is examined in depth at Ocean level because it is where most passages are made or lost.

Planning the Duration

Every resource calculation starts with the number of days. The planned duration is distance divided by a realistic average speed, not the best speed the boat has ever made. A 40-foot cruising yacht on a trade-wind crossing typically averages 5.5–6.5 knots over the ground, or 130–155 miles a day; in variable conditions, 100–120 miles a day is more realistic.

Then add margins. The diagram below shows how each resource depletes at a different rate, and why the target is the planned duration plus at least 25% plus an allowance for the unexpected (calms, gear failure, a diversion).

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Notice the shapes:

• Fresh food runs out first, whatever you do: you can only carry it for one to two weeks.
• Tank water without a watermaker falls steadily and is the hardest limit on duration.
• Dry stores last as long as you choose to carry them.
• Water with a watermaker stays nearly level as long as the watermaker and its power supply keep working. That "as long as" is the reason you still carry tank water for an emergency.

Worked example. Las Palmas to St Lucia, 2,700 miles. At an expected 135 miles/day the passage takes 20 days. Plan 20 × 1.25 = 25 days, and keep emergency water and food for a few days beyond that in case of dismasting or a long calm.

Water

How much?

Water is the first constraint. Allow:

A sound planning figure without a watermaker is 3 litres per person per day minimum in temperate waters and 5 litres in the tropics for drinking and cooking.

Worked example. Four crew, 25-day planned duration (including the 25% margin), tropical route: 4 × 5 L × 25 = 500 litres. Many skippers add a further reserve of 10% or more, kept in separate containers so that a contaminated or leaking tank cannot take it all. Keep at least two separate water systems (for example two tanks with separate valves, plus jerry cans) so that a leak, bad fuel contamination or a burst pipe cannot empty everything.

Water discipline

• Use saltwater for washing up and the first rinse, for cooking vegetables and pasta (half and half for taste), and for washing yourself, with a final freshwater wipe.
• Fit a foot pump or a saltwater galley tap and switch off the pressurised freshwater pump on passage.
• Record tank levels in the log every day. Water use above the plan in the first week is a warning that must be acted on early, not at the end.

Collecting water in an emergency

The diagram below summarises the three sources and the reserve strategy.

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A heavy tropical squall can give 50 litres or more an hour if you rig a catchment: plug the deck scuppers and run a hose from a deck drain to a tank filler, or hang a bucket under the boom gooseneck or the lowest point of a bimini or awning. Let the first few minutes wash salt off the deck and sails before you collect. Treat collected water (filter it, or add a little chlorine for tank storage, but never feed chlorinated water to a watermaker). Also put a handheld or manual watermaker in the grab bag: liferaft water rations last only a few days.

The watermaker

A reverse osmosis (RO) watermaker pushes seawater at high pressure (around 55–60 bar, 800 psi) through a semi-permeable membrane. Water molecules pass; salt is rejected and flushed overboard as brine. The diagram below shows the process.

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Seawater contains about 35,000 parts per million (ppm) of dissolved salt. Good product water is under 500 ppm (usually 200–400 ppm). Key care rules:

• Chlorine destroys membranes. Never run tap water or chlorinated tank water through the membrane. Flush with filtered product water only (most units use a carbon filter on the flush line).
• Do not run it in harbour, near oil or in silty water. The prefilters clog and oil fouls the membrane.
• Prefilters: check every day and change when the pressure across them rises. Carry plenty.
• Pickling: if the unit will stand idle for more than a few days (manufacturers vary, typically 5–7 days with a fresh-water flush, or 48 hours in hot climates without one), flush and fill it with a preservative such as sodium metabisulfite. Flush the preservative out before use.
• Monitor salinity: a conductivity (TDS) meter or salinity probe should divert product to waste if it goes over 500 ppm. A rising reading means the membrane or a seal is failing.
• Power: a 12 V unit making 30 litres an hour draws about 10–15 A, so 100 litres a day costs 35–50 Ah. Larger engine-driven or AC units make 100–200 litres an hour but need the engine or a generator running.

Plan as if the watermaker will fail. A crew that has been washing in freshwater for a week and then loses the watermaker can be in real trouble.

Food

Calories

A crew member on watch, in motion, often wet and cold, uses 2,500–3,000 kcal a day, and more in high latitudes. The diagram below shows the calculation.

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Worked example. 4 crew × 2,750 kcal = 11,000 kcal/day. × 25 days = 275,000 kcal. + 25% = about 344,000 kcal. If the 25 days already includes the margin, do not add it twice: decide which figure is the planning duration and state it clearly in your plan.

Calories do not translate easily to shopping lists, so most skippers plan meal by meal: list 25 days × 3 meals plus snacks, write a menu, then derive quantities (for example 100 g dry pasta or rice per person per main meal; 4 people × 25 days × 100 g = 10 kg).

What to carry

• Long-life staples: rice, pasta, couscous, oats, flour, dried beans and lentils, UHT milk, tinned meat and fish, tinned tomatoes and vegetables, vacuum-packed or freeze-dried meals, nuts, chocolate, dried fruit.
• Fresh food that keeps: wax-coated hard cheese, eggs (unrefrigerated and unwashed, turned every few days, they keep three weeks or more), cabbages, onions, potatoes, carrots, squashes, citrus fruit, apples. Store root vegetables in a dark, ventilated, cool place, never in plastic bags.
• Fresh food that does not keep: soft fruit, salad and bread. Eat these in the first week. Buy fruit at different stages of ripeness.
• Seasickness food: crackers, ginger biscuits, soups and other easy food for the first 48 hours.
• Fishing is a bonus, never part of the calorie plan.

Stow food in waterproof bags or containers, remove cardboard (which carries cockroach eggs), write the contents on tins in permanent marker (labels wash off in a wet bilge) and keep a stowage list.

Fuel and Power

Bunkering

Fuel on an ocean crossing is for charging, for motoring through calms, and for emergencies (entering harbour, man overboard, clawing off a lee shore). Work out consumption from engine hours in the log (a typical 40–50 hp diesel uses about 2–3 litres an hour at cruising revs, and about 1 litre an hour when only charging). Decide how many hours of motoring you will allow, then keep a reserve of at least 20–25% plus enough for a final approach and entry. Store any jerry cans securely on deck, and fit a fuel filter with a water separator that you can change at sea.

Electrical system design

On a long passage the batteries power the autopilot, instruments, navigation lights, refrigeration, watermaker and communications 24 hours a day. A power budget is essential: list every consumer, its current, and its hours of use per day, to get a total daily consumption in amp-hours. For a 40-foot yacht this is often 150–250 Ah/day at 12 V.

The diagram below shows a resilient system.

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The principles:

1. Several independent charging sources. Solar (silent, reliable in the tropics), wind (good upwind and in the trade winds, less so running dead downwind), a hydrogenerator (excellent on a fast passage), and the engine alternator as backup. If one fails you can still balance the budget.
2. A separate engine start battery, isolated from the house bank, so that you can always start the engine.
3. Protection on every circuit, and spare fuses of every rating.
4. Critical loads identified: navigation lights, VHF/AIS, a GPS and the radio for distress. Know which loads to shed (fridge, watermaker, laptop charging) if the budget fails.
5. Battery bank sizing: house capacity of at least two to three days' consumption so that one cloudy, windless day does not empty it. Lithium (LiFePO4) banks accept charge quickly and can be used to about 80% depth of discharge; AGM or flooded lead-acid should be kept above 50%.

Worked example. Daily consumption 180 Ah. Solar 400 W gives about 100 Ah/day in the tropics; a hydrogenerator at 6 knots gives about 6 A × 24 h = 144 Ah. Together they comfortably cover the budget without the engine. If the hydrogenerator fails, solar covers about half, and you need to run the engine about 2 hours a day (alternator net 50 A) or cut loads.

Spares and Tools

Engine spares

Without an engine you lose charging (unless you have other sources), the watermaker (if engine-driven), and the ability to motor out of danger. The diagram below shows the critical items and suggested quantities for an ocean passage.

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Fuel filters are the number one item: dirty fuel stirred up by ocean motion is the commonest cause of engine stoppage. Learn to bleed your fuel system before you leave, and carry the right tools, rags and a container for the old fuel. Carry at least two complete impeller kits and know how to change the impeller (and how to find broken vanes that have migrated into the heat exchanger).

Organising spares

The diagram below shows a typical spares inventory grouped by system.

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The critical rule: an unfindable part is a nonexistent part. Keep a spreadsheet (printed and digital) listing every spare, its quantity and its exact stowage location ("Locker 4, under port saloon seat, red bag"). Label every container clearly. Update the list when you use something. Carry the small, failure-prone parts (filters, impellers, seals, belts, fuses, bulbs, shackles, clevis pins, split pins) rather than whole assemblies, plus the materials to improvise (Dyneema, hose, hose clips, epoxy, plywood, wire).

Steering deserves special mention: test-fit the emergency tiller before departure, and know how you would steer with drogue or sail balance if the rudder itself failed. Carry spare autopilot drive belts, or a complete second autopilot drive: on a short-handed crossing autopilot failure means hand-steering 24 hours a day.

Tool kit

The diagram below lists the essentials.

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Check that your spanners and sockets actually fit every fastener on your engine, rig and steering before you leave. For rigging, carry a means of cutting standing rigging (bolt cutters, hydraulic cutter or a hacksaw with many spare blades) in case of dismasting, when the rig must be cut away before it holes the hull.

Rigging Inspection

The rig is the engine of a sailing yacht, and offshore it is under continuous cyclic loading for weeks. Inspect it aloft before every ocean passage and regularly during it. The diagram below shows the checklist, working from masthead to deck.

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What you are looking for:

• Masthead: sheaves turning freely, pins secure, no wear on halyard exits, nav light and VHF antenna secure.
• Spreaders: correctly angled (bisecting the angle of the shroud), tips secure and taped against chafe on sails.
• Wire: broken strands ("meat hooks"), especially where the wire enters a swaged terminal. Cracks in swages are a classic failure point: look with a magnifying glass.
• Turnbuckles and toggles: locking nuts or split pins in place and taped, no bent toggles.
• Chainplates: no cracks, rust weeps, or leaks below decks.
• Running rigging: chafe at sheaves, clutches and fairleads. On passage, move halyards a few centimetres every few days so that the same spot is not always on the sheave.
• Blocks and shackles: pins moused (wired or cable-tied), bearings smooth.

On passage, a daily walk round the deck checking split pins, sheets, lashings and chafe points is one of the most valuable habits an ocean skipper can teach the crew. Chafe destroys more gear on trade-wind passages than wind does.

Sail Repair

Sails suffer most on long downwind passages from chafe on spreaders and shrouds, UV damage and seam failure. The diagram below shows the techniques.

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Sequence for a tear:

1. Stop it spreading: reduce or drop the sail immediately. A small tear in a flogging sail becomes a large one in minutes.
2. Temporary patch: dry and clean the cloth (wipe salt off with fresh water and alcohol if possible), then apply sail repair tape to both sides with rounded corners so they do not peel.
3. Permanent repair: sew a patch of similar cloth over the tear using a zigzag or herringbone stitch with waxed thread, a sailmaker's palm and the right needle. Stitches should go through undamaged cloth around the tear.
4. Inspect: check the repair after the next period of use.

The photograph below shows a sailmaker's palm and needle with waxed thread. The palm (worn on the hand) holds a metal disc that pushes the needle through heavy cloth. Practise with it before the passage; learning in a gale is too late.

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Image: Elgewen, CC0 (public domain dedication), via Wikimedia Commons

Carry Dacron sailcloth of similar weight, adhesive sail tape, spinnaker repair tape for light sails, a palm, an assortment of needles, waxed thread, whipping twine, scissors and a seam ripper.

The Preparation Timeline

Ocean cruisers such as Tom Cunliffe and Jimmy Cornell stress that a good crossing is largely decided before the lines are slipped. A realistic programme for a first ocean passage starts six to twelve months ahead:

Allow time to fix the faults that the sea trial finds. A boat that is on the water for three days before departure is not ready; most skippers want a week or more of final shakedown sailing.

Choosing the season

The best time to cross is set by weather, not by holidays. Tropical cyclone seasons are the main limit: roughly June to November in the North Atlantic and Caribbean, November to April in much of the South Pacific and South Indian Ocean, and May to November in the western North Pacific. Typical windows are mid-November to January for the Canaries to the Caribbean (the Atlantic Rally for Cruisers sets off in November), and roughly March to May for crossing the Pacific from the Galapagos to French Polynesia, to be clear of cyclones before they start. Check the pilot charts, Ocean Passages for the World, and current Admiralty or NOAA cyclone information for the route.

Stowage for Heavy Weather

A boat that is comfortable at anchor can be lethal inside a knockdown. Before leaving, decide the following.

• Heavy weights low and central: batteries, tanks, anchor chain (consider moving some chain aft), tinned food, spares, tools. Never store heavy items high or in the ends.
• Every locker secured: a catch that holds in harbour often fails in a knockdown. Fit locking catches or bungee retainers to every locker, drawer and the oven.
• Loose gear: cushions, bottles, laptop and tools go in a locker or net. A loose 20 kg item thrown across a saloon at 90 degrees is a casualty.
• Deck gear: lash jerry cans, the dinghy, the liferaft (in its cradle with a hydrostatic release), solar panels and spare spars; check that nothing blocks the cockpit drains.
• Companionway: boards must be strong, hinged or tethered, and the crew must know how to close them from inside and outside.
• Water in the bilge: bilge pumps must work from both inside and outside the cabin, and the strum boxes must be clear.

The test is the "knockdown walk": stand in the middle of each cabin and ask what would move if the boat rolled to 90 degrees.

Fresh Food, Vitamins and Galley Practice

Keeping vitamin C

Lime juice and citrus fruit keep vitamin C for weeks; scurvy has not been a problem for yacht crews who eat fruit and root vegetables, but a crew eating only tins and dry stores for over six weeks risks vitamin C deficiency (tiredness, bleeding gums, slow healing). Carry vitamin supplements as insurance, and use sprouting seeds (mung beans, alfalfa, lentils) for fresh greens on long passages.

Cooking in a seaway

• A gimballed cooker with a fiddle rail and a cooking strap for the cook, so a roll cannot throw boiling water over them.
• One-pot meals that stay in the pan: stews, pasta dishes, curries, soups. A pressure cooker saves gas and holds contents in a seaway.
• Make-ahead meals for the first three days when the crew is seasick: sandwiches, flasks of soup, pre-cooked pasta.
• Rotate the cook; a cook in a seaway is a high-injury job (burns and scalds), so galley clothing, boots and gloves matter.

Gas calculation

A typical meal uses 0.05 to 0.1 kg of butane or propane. Three hot meals and several hot drinks a day for a crew of four use about 0.4 kg a day. A 25-day passage therefore needs about 10 kg of gas, plus a reserve of 50 percent. Pressure-cooker use or all-day cooking raises this figure.

Navigational and Communications Self-Sufficiency

A self-sufficient ocean yacht also carries enough information and communication to survive failure of its electronics.

• Navigation: a hand-held GPS and spare batteries, a sextant, tables, almanac, paper charts of the route and the destination, and a paper log. Charts of landfalls, and every diversion port (the Azores, Cape Verde, Bermuda), must be on board even if rarely needed.
• Weather: a second source for forecasts (HF voice or Navtex, plus a satellite device). Know how to read your own barometer trend if all else fails.
• Communications: a satellite phone or Iridium GO, an EPIRB (406 MHz, registered), a PLB on each watch crew, and a handheld VHF in the grab bag. See the Long-Range Communications lesson.
• Information: pilot books, tide tables for the landfall, cruising permits and a list of ports of entry. Carry paper copies of all documentation.

Cruising Paperwork and Provisioning Ashore

World cruising means arrival and clearance at each country.

• Ship's papers: registration (Part 1 British registry or Small Ships Register), insurance certificate, radio licence (Ship Radio Licence), the skipper's certificate of competence (the Yachtmaster plus the SRC/GMDSS), crew passports and visas, vaccination certificates and cruising permits for each country.
• Clearance: report to customs, immigration and the port authority on arrival and again on departure; fly the Q flag until cleared.
• Quarantine: many countries (Australia, New Zealand and some Pacific islands) forbid the import of fresh fruit, vegetables, meat, honey and wood products. Eat or dispose of them before arrival, and expect a biosecurity inspection and hull and bilge checks.
• Provisions in remote places: stock up in the last big port (Las Palmas, Panama, Galapagos) and do not assume supermarkets at your first landfall.
• Cost of cruising: budget for marina and mooring fees, fuel, insurance, port clearance, and repair. A reserve of at least 10 percent of the annual cruising budget should be set aside for breakages.

Worked Example: Diesel Range and Reserve

A 42-foot yacht has a 200 litre tank and a spare 60 litres in cans. The engine uses 2.5 L/hour at 1,800 rpm and the boat motors at 5.5 knots; charging with the engine in neutral uses 1 L/hour.

1. Range under power with 200 L: 200 / 2.5 = 80 hours, 80 x 5.5 = 440 nautical miles. With cans: 260 / 2.5 = 104 hours, 572 miles.
2. Charging plan: 2 hours a day for 20 days = 40 hours x 1 L = 40 litres.
3. Motoring allowance for light-wind stretches, say 36 hours at 2.5 L = 90 litres.
4. Harbour reserve: 20 litres for the last approach, entry and a possible go-around.
5. Total planned use: 40 + 90 + 20 = 150 litres. Carrying 260 L therefore leaves 110 L (about 42 percent) unused as a safety margin.
6. Check: the tank gauge is untrustworthy; use the engine hours log and measure the tank with a dipstick at the start of the passage.

Always keep the reserve for a lee-shore situation, since the most dangerous time to be out of fuel is at the end of a long passage when you are closing land.

Worked Example: Provisioning Plan for a Crew of Five

The crew is five for a 22-day Atlantic crossing, planned for 28 days with the margin.

• Water: 5 x 4 L x 28 = 560 litres for drinking and cooking. Tankage is 450 L plus 4 x 25-litre drums (100 L) as emergency, giving 550 L; make up the difference with 10 x 1.5 L bottles. The watermaker is a bonus.
• Food: 28 days x 3 meals x 5 people = 420 main meals. At 100 g pasta or rice per main meal for 100 meals this is 10 kg, plus potatoes at 250 g per meal for 60 meals (15 kg), and tinned meat, fish and vegetables at one tin per person per day for the remaining meals.
• Fresh: days 1 to 7, salad, fruit and bread; days 8 to 21, cabbage, carrots, onions and apples; after day 21, tins and long-life products.
• Gas: 12 kg in two 6 kg cylinders plus a reserve of 3 kg.
• Fuel: as the worked example above.

Check against the worst credible case, for example an extra 10 days of calm, and write down the point at which you start rationing.

Rationing and Contingency Planning

Plan before departure for the day the passage takes much longer than planned: a long calm, a damaged rig or a long beat in the wrong direction. A trigger point is a pre-agreed milestone at which you act. For example:

• At 60 percent of the planned passage time, if you have covered less than half the distance, review stores and options (diversion to a nearer port, such as the Azores or Cape Verde, or the Cocos).
• At 20 days with 5 days of stores left, move to rationing: water to 2 litres a day drinking only, food to a restricted menu, no fresh-water washing.
• If the stores are below a critical level, make a pre-decided diversion or call for help.

Survival rationing figures: a healthy person can live for days on 1 litre of water a day if resting, but this is a last resort, and dehydration impairs judgement long before it is dangerous. Keep emergency water in sealed containers, separate from the main tanks, plus the liferaft's own supply. The grab bag should include water and ration packs (see the liferaft and grab bag lessons).

Always plan with the worst credible case in mind: not the average speed but the speed you would make with a broken autopilot and one crew member ill.

Fuel Quality, Gas and Refrigeration

Diesel quality

Diesel can grow a "bug" (bacterial and fungal growth at the water-fuel interface) which blocks filters and fouls injectors, particularly in tropical heat. Water enters through vents and poor fuel. Keep tanks full to limit condensation, fit a water separator and a drain, and take a sample in a clear jar at bunkering. Carry a filter funnel (a fine-mesh funnel which also filters water), spare primary filters, and fuel treatment (biocide) as the manufacturer recommends. Every tank should have an inspection hatch and a drain, so you can clean it. Rough weather stirs up sediment from the bottom of a tank and blocks filters when you most need the engine: a routine filter change before the passage, and spare filters within reach of the engine, prevent that.

Gas for cooking

LPG for the galley must be stored in a ventilated gas locker that drains overboard (LPG is heavier than air) and the gas system checked for leaks with soapy water, never with a flame. Calculate consumption: a typical cooking use is 0.3 to 0.5 kg per day for a crew of four, so 25 days needs 8 to 12 kg plus a reserve: carry at least two cylinders and a means to refill in remote areas (adaptors differ between countries). Know the solenoid shut-off and make it routine to shut off at the cylinder at night.

Refrigeration

A fridge draws 3 to 6 A on average (30 to 70 Ah a day in the tropics), the largest single load on many yachts. Insulate well, use top-opening boxes, and have a plan for when it fails: dishes that need no fridge, UHT products and canned goods. Frozen food will not last more than a few days if the compressor fails.

Psychological Preparation and Routine

Weeks at sea mean monotony, fatigue and close quarters. The skipper plans for human endurance as carefully as for diesel.

• Routine: fixed meal times, a clear watch system, scheduled maintenance, and a daily chart plot and logbook entry mark days and prevent drift into apathy.
• Rest: a crew member who cannot sleep is a hazard to themselves and the boat. Protect sleep; the watch system lessons cover details.
• Morale: celebrate milestones (halfway, the equator, birthdays), share cooking, and keep entertainment (books, music, downloaded programmes) available.
• Communication with shore: regular email or satellite contact helps, but beware of obsessive weather checking.
• Warning signs: persistent low mood, withdrawal, irritability or sleep disturbance in anyone, including yourself. Talk early; consult medical advice by radio if needed.
• Pre-departure honesty: discuss with each crew member their expectations and limits before the passage, not during it.

Emergency Contingencies Where Self-Sufficiency Is Tested

Steering failure

Carry an emergency tiller that fits the rudder stock and know where it is stowed, plus a spare autopilot drive and a plan for emergency steering by drogue or sail balance if the rudder is lost. Practise fitting the emergency tiller in harbour: it should take no more than a few minutes. If the rudder is lost entirely, steer using sail balance and a drogue towed astern on a bridle, and consider a jury rudder rigged from a spinnaker pole, a cabin sole board or a lifeboat oar.

Dismasting

Cut the rig away only if it threatens to hole the hull: use the bolt cutters or hydraulic cutters you carry. Retrieve what you can (the boom and sails make a jury rig). Start the engine only after checking that no lines are in the water to foul the propeller. Prepare a jury rig plan before leaving: for example, a spinnaker pole as a mast, stayed with halyards and spare lines. Report by VHF, DSC or satellite as the situation dictates.

Engine failure

On a long passage the engine is a charging source and a safety back-up. Know the fault-finding order: fuel (tank contents, valve, filter and bleed), air (intake), electrics (battery, starter, fuses) and cooling (raw-water impeller, strainer, belts, exhaust elbow). Practise bleeding the fuel system and changing the impeller before departure. Keep a laminated fault-finding checklist at the engine.

Water ingress

Know every seacock and where it is, and how to close it. Carry softwood bungs tied to each, a collision mat, an emergency pump (manual pumps of high capacity), and know how to find the source of a leak: smell, listen, taste (salt or fresh) and trace. This is a pure seamanship item, and it is also a matter of stores: a sinking yacht needs working pumps, power and effective crew.

Worked Example: Self-Sufficiency Plan for a Pacific Passage

Passage: Galápagos to the Marquesas, 3,000 miles, 4 crew, 42-foot yacht. Expected 150 miles/day = 20 days; plan 25 days.

• Water: watermaker 30 L/hr (12 A). Tankage 400 L plus 60 L in jerry cans. Without watermaker: 4 × 4 L × 25 = 400 L, so the tanks alone just cover drinking and cooking if the watermaker fails on day one. Run the watermaker 3 hours/day (90 L) to keep the tanks full.
• Food: 25-day menu planned, plus 5 days of emergency dry stores. Fresh fruit and salad for days 1–7, cabbage, carrots, onions and potatoes for days 1–20, then tins.
• Power: budget 200 Ah/day (including 36 Ah for the watermaker). Sources: 500 W solar (about 120 Ah/day), hydrogenerator (about 130 Ah/day at 6.5 knots). Engine charging only if both fail.
• Fuel: 200 L tank + 40 L cans. Motoring allowance 60 hours at 2.5 L/hr = 150 L, leaving 90 L reserve.
• Spares and repair: engine kit as above, second autopilot drive unit, 2 spare halyards, sail kit, rig cutters. Spares spreadsheet printed and stowed by the chart table.
• Checks: full rig inspection aloft in the Galápagos; daily deck and chafe walk at 0900; weekly bilge, steering and seacock check.

Worked Example: Power Budget

A 40-foot yacht crossing the Atlantic has these loads.

This is heavy for a 40-foot boat; examine each line. Cut the autopilot to a more efficient unit or hand steer in light winds; use LED lights, run the watermaker only when charging, and so on. Suppose, after savings, the total is 220 Ah per day. A house bank of 400 Ah should be discharged only to 50 percent (200 Ah usable) for battery life, so the bank covers about a day with no charging. With 500 W of solar giving 120 Ah in the tropics and a towed hydrogenerator giving 100 Ah at 6 knots, there is 220 Ah, which matches the demand without the engine. If one source fails, you shed loads or run the engine for one to two hours a day.

Exam-Style Tips: What the Examiner Expects

• State the duration, the crew, the figures, and the margin: "25 days at 3 L per person per day, 4 crew, 300 L plus 25 percent reserve".
• Distinguish the planning duration from the margin, and do not add margin twice.
• Show that you know what fails first and what you would do about it.
• Quote the maintenance routine: daily deck walk and chafe check, weekly rig, bilge, seacock, and steering check.
• Be ready to explain how you would carry on after a failure of each system: water, power, steering, rig, engine, navigation.
• A good answer ends with the plan B.

Common Mistakes

• Planning on best-case speed and so carrying too little.
• Relying entirely on the watermaker with no tank reserve, or ruining it by running chlorinated water through the membrane.
• No power budget, or a budget that assumes every charging source works all the time.
• Spares without a list: hours lost searching lockers in a seaway.
• Wrong spares: impellers or filters for a different engine model, or no tools to fit them.
• Skipping the rig inspection because "it was fine last season".
• Letting a sail flog while deciding what to do about a small tear.
• Fresh produce in plastic bags, which sweats and rots within days.

Summary

• Plan the duration on realistic speeds, then add at least 25% and an extra reserve.
• Water: 3 L/person/day (temperate) to 5 L (tropics) for drinking and cooking. Use saltwater for washing, keep separate reserves, and treat the watermaker as a bonus that can fail.
• Food: 2,500–3,000 kcal/person/day, planned meal by meal, with fresh food eaten first and long-life stores for the rest.
• Power: a written budget, multiple independent charging sources, an isolated start battery, and a plan for shedding loads.
• Spares: organised by system, catalogued with locations, focused on small, failure-prone parts and on tools that fit.
• Inspect the rig aloft before departure and fight chafe every day. Repair sails early: stop, tape, sew, inspect.

Check Your Understanding

1. A passage of 2,400 miles is expected at 120 miles a day. What duration should you plan stores for?

Answer: 2,400 ÷ 120 = 20 days. Plus 25% = 25 days, with an additional emergency reserve beyond that.

1. Calculate the minimum drinking and cooking water for 5 crew on a 25-day tropical passage without a watermaker.

Answer: 5 × 5 L × 25 days = 625 litres, stored in at least two separate systems.

1. Why must chlorinated water never pass through an RO membrane, and what product-water reading suggests the membrane is failing?

Answer: Chlorine chemically attacks and destroys the thin-film membrane. Product water above about 500 ppm dissolved solids indicates a failing membrane or seal.

1. What does "pickling" a watermaker mean, and when is it needed?

Answer: Flushing and filling the membrane with a preservative such as sodium metabisulfite to prevent bacterial growth when it will stand idle for longer than the manufacturer's limit (typically a few days, less in the tropics). It must be flushed out before producing drinking water again.

1. Your daily consumption is 160 Ah. Solar gives 90 Ah and wind gives 50 Ah. What is the shortfall, and how might you deal with it?

Answer: 160 − 140 = 20 Ah/day. Shed loads (fridge, watermaker running time, laptop charging), or run the engine for about half an hour to an hour with a good alternator.

1. Why should the engine start battery be isolated from the house bank?

Answer: So that heavy house use cannot flatten the start battery. You can always start the engine to charge the house bank, motor out of danger, or run an engine-driven watermaker.

1. Which engine spare is usually the top priority, and why?

Answer: Fuel filters (primary and secondary). Ocean motion stirs up sediment and water in the tank, blocking filters and stopping the engine, often at the worst moment.

1. What is meant by "an unfindable part is a nonexistent part", and how do you avoid it?

Answer: A spare you cannot locate in an emergency is as useless as one you never bought. Keep a catalogue of every spare with quantity and exact stowage location, and label containers clearly.

1. You find a 15 cm tear in the leech of the genoa. What do you do, in order?

Answer: Furl or drop the sail to stop the tear spreading; clean and dry the area and apply sail repair tape on both sides with rounded corners; when conditions allow, sew a cloth patch with a zigzag stitch through sound cloth; then inspect after use.

1. Name four things you look for in a rigging inspection aloft.

Answer: Any four of: masthead sheave wear and pins; spreader alignment and tip security; broken wire strands or cracked swages; turnbuckle locking pins; chainplate cracks or leaks; halyard chafe; shackle pins moused and blocks running freely.

1. A yacht has 400 Ah of house battery capacity, a daily load of 180 Ah and no charging for one day. What is the battery state of charge at the end of the day, and why is this a problem?

Answer: It has used 180 of 400 Ah, leaving 55 percent, but regular discharge below 50 percent shortens battery life, and a second day without charging would take it below that. The remedy is to run charging sources, shed loads or run the engine.

1. List four causes of a diesel engine stopping offshore and the first check for each.

Answer: Fuel starvation (check filters and water separator, then bleed), air (check intake), electrical (battery and starter connections, fuses), and cooling or overheating (raw-water strainer and impeller, belts).