Useful Guides for Marine Galvanic Isolators

What are Marine Galvanic Isolators?

Here you’ll find a number of useful tips, videos, and instructions on how to select and install your ideal marine galvanic isolator.

A brief overview:

When you connect your boat to a marina electrical supply you also connect your boat to all the other boats in the marina via the earth connection in your shore power mains lead. This creates a pathway for small electrical currents to flow from one boat to another.

Unfortunately this pathway leads to increased corrosion of the underwater metals and results in rapid loss of anodes and increased pitting and deterioration of hulls, propellers, shafts, outdrives etc. We can protect against this problem by installing a galvanic isolator.

Can I really install a marine galvanic isolator in less than 30 seconds?
Yes you can - Safeshore make it easy!

Can I really install a galvanic isolator in under 30 seconds?
Yes you can! Safeshore make it easy!

  1. Simply plug into the shore power lead and you are instantly protected.
  2. Controls both galvanic & stray current corrosion in just 30 seconds, job done!
  3. 70 amp Safeshore isolator lifetime warranty Install in boat or on shore power pedestal.
  4. Supplied with standard blue UK / Europe plug & socket. Selling the boat? Unplug & take it with you! Suitable for all standard 16 amp marina power supplies.
  5. Leave shore power connected Protects anodes, skin fittings, shafts, props, engines, outdrives & hulls.
  6. Also available with status monitor for maximum protection and easy testing.
  7. Special products : If you are lucky enough to have a commercial 32A power supply in your marina we supply upgraded versions of plug and play units. These specialist units contain our 100 amp internal isolator with extra heavy duty cables and connection plug and sockets. Please phone or email for details of these special products.

A Guide to Galvanic Corrosion and Isolation

How to Install a Galvanic Isolator

30 Second Installation - In-line Isolators


Question How do galvanic isolators work?
AnswerA galvanic isolator is inserted into the earth line of the shore power lead. This can be done internally in the boat or by using our plug in waterproof units you simply unplug the shore power lead from your boat, plug the lead into the isolator and re-insert the isolator flying lead back into the shore power inlet. Job done!

The isolator now creates a block for damaging galvanic currents minimising the risk of corrosion. In the event of an electrical fault onboard the isolator senses the fault condition and ensures your trips and rcd protection operate as normal ensuring safety onboard.

Question If the earth cable causes the problem why not just remove it?
AnswerThe earth cable is essential for safety. In the event of an electrical fault onboard the earth wire ensures the rcd / fuses/ breakers operate correctly and disconnect the mains electrical supply until the fault is rectified.
Question How easy is it to fit an isolator?
AnswerInternally fitted units are inserted into the incoming earth line between the shore power inlet socket on the boat and the consumer/distribution unit onboard. This is done by locating the incoming shore power lead, cutting the earth cable at a convenient point and inserting the isolator using terminal connectors provided.

The live and neutral cables of the shore power lead remain untouched. We supply excellent instructions and diagrams but if you do not feel competent to proceed we would recommend our “Plug and play” units. These units plug into the shore power leads either at the boat or the shore power pedestal of the marina. No electrical knowledge needed… Just 30 seconds to install!

Question How many Amps do I need?
AnswerThe amperage rating of the isolator is the amount of current the isolator can handle under severe fault conditions. The isolator must be able to handle more than the available current supplied to the boat. Usually UK marina supplies are either 16 or 32 amps so the isolator must be able safely handle at least 20% more than the maximum current available to comply with legislation. Realistically the higher the rating the more reliable the isolator.
Question What is the purpose of status monitoring?
AnswerUnits with status monitoring measure the current flowing through the isolator. If the current flow increases beyond a preset threshold led’s will illuminate to indicate a fault condition. Safeshore models with monitoring also offer increased galvanic protection and easy testing of the installation.
Question How reliable are your isolators?
AnswerSafeshore have now been supplying the marine industry for over 20 years. Our reliability record is superb reflected by our lifetime warranty on all products.
Question What is the difference between galvanic and stray current corrosion?
AnswerGalvanic corrosion is caused by the interaction of differing metals whilst connected together and in contact with the water. Stray current corrosion is caused by poor electrical connections, poor wiring in contact with bilge water and “leaky” power supplies. These currents are often transmitted down the shore power earth wire. A galvanic isolator will help to block both galvanic and stray current corrosion.
Question Which isolator do you recommend?
AnswerIf you’re looking at DIY installation, our GI-70SM or GI-70SMI models both offer maximum protection, easy testing, and fault monitoring. The GI 70SM has remote monitoring, so if you plan to fit it under the floor this allows the monitor to be installed remotely on the dashboard. GI-70SMI has internal monitoring so if fitting the isolator in an easily viewable position this is the one to use. For “Belt and braces” reliability models GI-100SM or GI-100SMI are the upgraded versions.
Question My requirements exceed the ratings of your products - can you help?
AnswerWe supply upgraded versions of the inline units specifically designed for use with 32 amp commercial power supplies. These units are fitted with 100 amp internal isolator and heavy duty cables / large blue 32 amp plug and socket. Please phone for details.

Quick check: Not sure which supply you have? Simply measure across the diameter of the plug with exposed pins: 32 amps = 56mm……(16 amps = 43mm)

Question Do you Supply to the Trade?
AnswerGenerous trade discounts available: Tel 01977 513607 or request our trade price list….Email: [email protected]. or click on Contact button

If you’ve got more questions, send us a message! Our experts will get back to you as soon as possible.