# Galvanic Corrosion Testing Long Beach | Stray Current & Isolators | Long Beach Marine Electric

> Zincs gone in weeks? Galvanic corrosion and stray current testing with a reference electrode, plus galvanic isolators, in Long Beach marinas. Call today.

URL: https://longbeachmarineelectric.com/galvanic-corrosion-testing/

Repair · Same-day callback

# Galvanic Corrosion & Stray Current Testing in Long Beach

Zincs gone in weeks, pitted props, a flaking outdrive? Reference-electrode testing finds out whether it's galvanic corrosion or stray current, then fixes it.

[Call (562) 374-7233](tel:+15623747233) [Get a Free Estimate](/contact/)

-   ABYC E-2 cathodic protection
-   Silver/silver chloride reference electrode
-   200 mV protection shift
-   Galvanic isolators (ABYC A-28)
-   Isolation transformers
-   Free estimate within 24 hours

Last updated: October 6, 2026

[Long Beach Marine Electric](/) connects boat owners with licensed, insured marine electricians for galvanic corrosion testing and stray current diagnosis: measuring hull potential with a silver/silver chloride reference electrode, finding leakage on board, and installing galvanic isolators or isolation transformers. In a crowded marina, boats are connected to each other through the shore-power safety ground, so a neighbor's problem can eat your zincs. Testing tells you whose problem it is.

## What happens on the first visit

1.  Hull potential readings with a silver/silver chloride reference electrode, with shore power connected and disconnected, to separate a marina-side problem from an on-board one.
2.  Check of the bonding system: continuity from each underwater metal (shaft, strut, rudder, through-hulls, outdrive) to the anodes.
3.  Leakage-current test of the boat's DC and AC systems. A small DC leak to a bonded fitting is classic stray-current corrosion.
4.  Anode condition and type check: zinc, aluminum or magnesium suited to salt water and to your underwater metals.
5.  A written finding and options: anode changes, bonding repair, a galvanic isolator or an isolation transformer, each with a price.

## Galvanic corrosion vs stray current

**Galvanic corrosion** happens when two different metals are connected and immersed in the same seawater. The less noble metal corrodes to protect the more noble one. That's what sacrificial anodes are for. Connected to shore power, every boat's underwater metal is also tied to every other boat's through the green safety ground, so a dock of boats becomes one big galvanic circuit.

**Stray current corrosion** is faster and worse: DC current leaking from a wiring fault, on your boat or nearby, leaves through an underwater fitting and takes metal with it. It can destroy anodes, props and outdrive legs in weeks rather than seasons. The symptoms look similar from the dock, so measurement is the only way to tell them apart.

## What a reference-electrode test tells you

A silver/silver chloride reference electrode lowered into the water next to the hull measures the boat's corrosion potential in millivolts. The working rule from cathodic-protection practice is that adequate protection shifts a metal's potential at least **200 mV more negative** than its natural resting voltage. Aluminum is the special case: it rests around -760 mV in seawater, needs about -900 to -950 mV for protection, and shouldn't be driven past about -1,100 mV, where overprotection blisters paint and damages the metal. That's why an aluminum outdrive needs the right anode, not just more of them.

Taking readings with shore power on and off, and with on-board breakers switched one at a time, shows whether the problem comes in through the shore cord or starts on board.

## Galvanic isolator or isolation transformer?

A **galvanic isolator** sits in the shore-power ground and blocks the low-voltage galvanic currents between boats while still passing fault current to keep the ground safe. A fail-safe, ABYC A-28-compliant unit such as the ProMariner ProSafeFS lists at about $605 before installation. An **isolation transformer** breaks the direct connection to shore power entirely. It's the stronger fix, also removes the need for an onboard ELCI if mounted within 10 feet of the inlet, and is common on larger yachts, but it's heavier and costs more. Read [galvanic isolator vs isolation transformer](/guide/galvanic-isolator-vs-isolation-transformer/) for the full decision.

## Insurance, warranty and who pays

Corrosion testing and isolator installation are owner-paid. Corrosion damage itself is usually treated by insurers as wear, not a covered loss, which is why catching it early with a test is cheaper than replacing an outdrive. Testing typically takes one to two hours at the slip. Anode replacement on shafts and struts waits for a haul-out or a diver.

## What's included

-   Hull potential readings (shore power on/off)
-   Bonding system continuity check
-   DC and AC leakage testing
-   Anode type and condition assessment
-   Galvanic isolator installation
-   Isolation transformer assessment
-   Bonding repair
-   Written readings and recommendations

## DIY vs cheap fix vs proper corrosion work

DIY

Cheap operator

Proper marine work

Diagnosis

Look at the zincs

Replace zincs

Reference-electrode readings, power on and off

Anodes

More is better

Whatever fits

Right metal and size for the readings

Bonding

Not checked

Not checked

Continuity verified to every fitting

Shore-power path

Ignored

Ignored

Isolator or transformer where needed

Result

Zincs gone again

Damage continues

Protected range confirmed by measurement

## Related resources

-   [Zincs Wearing Out Fast? Galvanic vs Stray Current Corrosion](/guide/zincs-wearing-out-fast/)
-   [Galvanic Isolator vs Isolation Transformer: Which Does Your Boat Need?](/guide/galvanic-isolator-vs-isolation-transformer/)

## Sources

-   [BoatTest: reference cell testing and protection levels](https://boattest.com/article/reference-cell-testing-know-thy-corrosion-protection-level)
-   [Hardin Marine: ProMariner ProSafeFS galvanic isolator](https://www.hardin-marine.com/p-97669-promariner-prosafefs-galvanic-isolator.aspx)
-   [Cruising World: ABYC E-11 ELCI and isolation transformer exception](https://www.cruisingworld.com/?p=40379)

Outdrive pitting?

Stray current can destroy metal in weeks. Get it measured now.

[(562) 374-7233](tel:+15623747233)

Mon–Sat 7am–6pm · Free estimate within 24 hours

Standards applied

-   ABYC E-2 (cathodic protection)
-   ABYC A-28 (galvanic isolators)
-   ABYC E-11 (AC & DC systems)
-   Ag/AgCl reference electrode

[Estimate your cost](/tools/marine-electrical-cost-estimator/)

How it works

## How galvanic corrosion testing works

1.  01
    
    ### Tell us what's corroding
    
    Zincs, props, outdrive or through-hulls, and how fast. You get a callback the same day.
    
2.  02
    
    ### Measure
    
    Reference-electrode readings with shore power on and off, plus bonding and leakage checks.
    
3.  03
    
    ### Fixed price
    
    A written price for the fix: bonding repair, anodes, isolator or transformer.
    
4.  04
    
    ### Re-measure
    
    Readings are taken again after the work to confirm the hull is in the protected range.
    

Get galvanic corrosion testing at your slip today

Same-day callback. Written price before any work.

[Call (562) 374-7233](tel:+15623747233) [Get a Free Estimate](/contact/)

Straight answers

## Galvanic Corrosion Testing questions

### Why are my zincs disappearing so fast?

Either they're doing their job against a large galvanic load (common in crowded marinas through the shore-power ground), or stray DC current is leaking from a wiring fault on your boat or a neighbor's. A reference-electrode test with shore power on and off tells you which.

### Can my neighbor's boat corrode mine?

Yes. Boats connected to the same shore-power system share the safety ground, which links their underwater metals. A boat with poor protection or a fault can drain your anodes. A galvanic isolator or isolation transformer breaks that link.

### Do I need more zincs?

Not necessarily. More anode surface can overprotect some metals, especially aluminum outdrives, which shouldn't be driven past about -1,100 mV. The right answer comes from measuring hull potential, not adding anodes.

### Can this be tested without hauling the boat?

Yes. Reference-electrode readings, bonding checks and leakage tests are all done at the slip. Replacing shaft or strut anodes needs a diver or a haul-out.

### Who does the work, and how do I know they’re qualified?

Long Beach Marine Electric is a free service that connects you with an independent, licensed and insured marine electrician who holds the American Boat & Yacht Council (ABYC) Marine Electrical Certification. Ask your electrician for proof of license and insurance before work starts.

## Related services

[Shore Power RepairPedestal keeps tripping, burnt inlet, no AC at the panel. Covers 30A and 50A inlets, cords, ELCI breakers and leakage faults.](/shore-power-repair/) [Boat RewiringAging automotive wire replaced with tinned marine cable, new AC/DC panels and labeled circuits, built to ABYC E-11.](/boat-rewiring/) [Yacht Electrical Systems50A and 100A 240V service, generator transfer switches, isolation transformers and digital switching on 40 ft+ yachts.](/yacht-electrician/)

Find out what's eating your zincs

[Call (562) 374-7233](tel:+15623747233) [Get a Free Estimate](/contact/)