Galvanic isolation

Possible galvanic problems

Erosion of saildrive

Erosion of propellers

Erosion of rudder stock

Erosion of thru hulls

Prop-speed/saildrive paint flaking off

Bottom paint around thruhulls flaking off

Dangers

When zinc anodes are not replaced

When connected to shore power

When there are wiring issues on a sailboat

Best practices shore power

Have an isolation transformer installed OR

Have a electrolysis blocker installed

Recommendation
Test your system annually to ensure the electrical systems are not causing anodes to be consumed at a fast rate

Resources
Presentation Marine Galvanic Corrosion Made Easy: File:Marine Galvanic Corrosion Made Easy.pdf
Cathodic testing procedure: External Link
Electrolysis Blocker Datasheet: File:Shore Power Electrolysis Blocker.pdf