Load shedding protects an electrical source by disconnecting selected loads before an overload develops into a complete loss of power.
If a blackout does occur, recovery involves more than starting a generator and reconnecting every circuit. Power must be restored in a controlled order while preserving starting energy, supporting essential systems and avoiding another overload.
This free technical guide gives yacht owners and prospective buyers a practical introduction to common load-shedding and blackout-recovery arrangements. It covers generators, shore supplies, inverters, battery-backed essential circuits and both automatic and manual recovery procedures.
Why load shedding and blackout recovery matter
A loss of electrical power may affect steering auxiliaries, engine-room ventilation, fuel and cooling pumps, lighting, navigation equipment, communications and bilge systems at the same time.
Battery-backed equipment may continue operating temporarily, which can make the full extent of a blackout difficult to recognise. A partial loss of one bus section, phase or control supply can be particularly confusing when other equipment remains energised.
Effective recovery depends on identifying essential loads, maintaining reliable generator-start and control power, bringing an alternative source online and restoring equipment in stages. The first priority is keeping the yacht safe—not returning domestic services as quickly as possible.
What this guide covers
The guide explains:
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The difference between overload prevention, load shedding and blackout recovery
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Normal, essential and emergency electrical supplies
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Essential, operational, deferrable and high-demand loads
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Overload detection using current, voltage, frequency and available reserve
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Automatic load-shedding stages, priorities and delays
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Generator auto-start, stabilisation and bus connection
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Generator-start batteries, control power and supporting auxiliaries
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The immediate consequences of a main-bus blackout
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Emergency batteries, UPS units and emergency generators
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Manual and automatic blackout-recovery procedures
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Controlled and sequential restoration of electrical loads
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Preventing automatic restarts from causing another overload
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Reduced-power operation after a fault
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Testing load shedding, standby generation and recovery sequences
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Crew roles, communications, documentation and blackout drills
Who is this guide for?
This guide may be particularly useful if you are:
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Considering the purchase of a motor yacht
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Assessing a yacht for extended or offshore cruising
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Trying to identify essential and non-essential electrical loads
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Reviewing generator auto-start and transfer arrangements
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Experiencing nuisance trips, failed starts or recurring power losses
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Planning electrical maintenance, upgrades or a refit
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Developing or reviewing a blackout-recovery procedure
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Looking to improve crew preparedness for electrical failures
Questions the guide will help you answer
After reading the guide, you should be better placed to answer:
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Which systems must remain available during an electrical failure?
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Which loads can be shed safely to protect the active power source?
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What measurements trigger automatic load shedding?
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Do the current load priorities reflect the yacht’s actual equipment?
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Can the standby generator start, stabilise and accept load automatically?
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Does generator starting depend on a shared battery, fuse or control supply?
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Which services remain available immediately after a blackout?
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How long will emergency batteries and UPS units support their connected loads?
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In what order should equipment be restored after power returns?
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Could several motors, chargers or pumps restart together and cause another trip?
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Can the crew recover power manually if the automatic system fails?
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Is a concise recovery procedure available at the operating positions?
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Have load shedding and blackout recovery been tested as a complete sequence?
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Can more than one person perform the recovery procedure in darkness and under pressure?