Marine Corrosion Education

Educational factual identification, understanding and elimination of the CAUSE of meal corrosion

Eliminate the CAUSE of marine corrosion with SeaBis Master System, permanently.

Training and reference. Further assistance, e-mail Glen Bishop:

We provide a 8 year money back guarantee because we are successful.
How To Stop Metal Corrosion must be complied with.


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Marine corrosion education: permanently eliminate the CAUSE by identifying then and repairing it. The SeaBis Master System is guaranteed for 8 years - we will either eliminate the CAUSE of metal corrosion or pay you your money back. How To Stop Metal Corrosion must be complied with. SeaBis Master is an industrial grade mini-computer with 20 years life. It is the simplest and most direct way to eliminate marine corrosion. Marine corrosion is caused by stray current. We eliminate ALL stray current. The result is your vessel is disconnected - Tech speak - Open Circuit to the World. No (electrical) current can flow between your vessel and the World so there can be no electrolysis. Permanently.

You do not need a Blocker or impressed current when you use SeaBis Master System. SeaBis Master with How To Stop Metal Corrosion is far better.

•Adding additional Anodes will only cost you more money than SeaBis.

•External references, proof we are correct, at the last page.

Author: Glen Bishop. My background:

I have been continuously fighting metal corrosion since I was 19.  The last 8 years I provide a publicly visible written 8 year money back guarantee:  "We will either eliminate the CAUSE of metal corrosion or pay you your money back.  With the provision How To Stop Metal Corrosion is fully complied with."  Do a Google search for SeaBis System. There has never been a genuine claim. Ask your supplier if he provides a written guarantee... then sight it!

Ask questions, then understanding is easier:

1: Why is metal corrosion on fences more at the bottom than the top?  The bottom is nearer the humidity of the Earth so is more vulnerable to current flowing to the Earth. (the Earth we stand on. Not the mains power supply earth).

2: Why does the metal corrosion on radiators occur before the engine body?  Radiators have a lower electrical resistance than engine bodies and most other harder metals so pass the majority of stray current that causes electrolysis - metal corrosion through themselves. That results in metal corrosion we are only to familiar with.

3: Why do vehicles in damp areas corrode more than in dry areas?  The tires are rubber so a good insulator, unless there is greater than 10% humidity. Then the rubber tire ceases to insulate the vehicle from the Earth.

4: Why do aircraft suffer from electrolysis? Clouds have greater than 10% humidity. The air around aircraft, in clouds, contains more than the tolerance level of 10% humidity - any metal in contact with the Earth, even remotely through the air, passes stray current to the Earth so causing electrolysis.

5: Why are boats and yachts more prone to stray current causing marine corrosion than vehicles?  They are sitting in a good conductor to the Earth - water.  Whereas vehicles are insulated from the Earth, providing their tires are dry 97% of the time.  For an explanation of 97% see do a Google search for SeaBis System and Questions or contact me:

6: Why do small to medium trucks, suffer from electrolysis when the large commercials do not?  The latter are designed differently. We can correct that situation with SeaBis Master.  That leads me to SeaBis System. 

The SeaBis System:  measures current flowing to the Earth while your equipment is fully powered - essential. The User disconnects equipment until SeaBis indicates Normal. The last equipment you disconnected was the cause. Now follow How To Stop Metal Corrosion. Free diagnostic support with SeaBis Master.

Procedure to eliminate the CAUSE/S at the bottom of this page.


Marine Corrosion Education:

Marine corrosion is ongoing to ALL metal that makes contact with the Earth, by air, sea or land. It is termed electrolysis. Some use terms stray current or rust. This article examines the three-step process to stop marine corrosion: identify marine corrosion, understand the cause and eliminate the cause.  The same process applies to all metal in all environments. Air: humidity in clouds. Land: humidity in air or land. Sea: a perfect conductor to the Earth.

Marine corrosion may take any or multiples of several forms. Some typical examples are shown in Figure 1.

Electrolysis dissolves metal, 24 hours, every day. Permanently. Some call this stray current or "rust"

Step 1: identify the cause of marine corrosion: electrolysis
 • Propeller
 blades dissolve
 • Metal under the
paint  dissolves
 • Welds have a lower
resistance to current
so dissolve first
Propellor corroded Paint repair Welds dissolve before sheet metal
 • Plumbing  corrosion.
White growth is typical
 • Radiator core dissolves
so becomes porous
 • Patches of electrolysis
are caused by lower
resistance to current flow
Plumbing electrolysis Radiator leaks Patches of electrolysis


Step 2: understand the cause of marine corrosion - stray current

Stray current is dependant on an electro - chemical reaction.
Eliminate the stray current and you eliminate electrolysis:
  No SeaBis System     With SeaBis System  
Metal stray current causes corrosion Stray current Metal corrosion cause eliminated No stray current
  Stray current causing corrosion     No corrosion  


Understand Marine Corrosion

The Science behind marine Corrosion

Electrolysis, which continuously dissolves metal, every hour of every day is the cause of corrosion. Stray current causes electrolysis.   It is sometimes called "stray current rust." Corrosion occurs whenever damp to wet metal or a heating / cooling system or a metal connection to the earth that is not perfectly dry at least 97% of time. Batteries are the primary source of direct current  (DC), however mains power generated DC has the same effect.  Metal particles are dissolved by the DC electric current to the Earth via water, land or air, taking your metal with it - marine corrosion.

All electronics must use DC.  They cannot operate without it. The battery’s DC - direct current - always flows in the same direction, carrying particles of your metal with it. In contrast, mains power is alternating current (AC) that reverses direction every half cycle (e.g., a 60 Hertz current reverses itself every 1/120 of a second) so dissolved particles are replaced every alternate half cycle. Therefore, alternating current cannot cause electrolysis corrosion.

The Causes of Marine Corrosion are:

Rust has very low corrosive ability compared to electrolysis. It requires a humidity content in the air of 10% or greater, to exist.  Even the Gobi desert exceeds that. Rust is easily prevented by paint or plating after all electrolysis CAUSES are eliminated.  Remember the bottom of fences corrodes first?  - It is nearer the humidity of the Earth.

Compared to electrolysis corrosion, galvanic corrosion also has low corrosive ability. Galvanic corrosion can be eliminated by anodes but only after electrolysis is eliminated. Sacrificial anodes can then work as designed.

Galvanic corrosion is caused by the natural voltage between two different metals in a conducting medium such as any type of humidity greater than 10%, even atmospheric humidity. The natural voltage never exceeds 1.2 volts and the current is in the millionths of an amp. A one-kilogram anode produces one-millionth of an amp of protective current. This can be demonstrated with two metal hulls, one inside the other and a sophisticated micro amp clamp meter or, much cheaper and more accurate by SeaBis Master.

Electrolysis varies from one thousandth of an amp to several amps  of current. I measured 9 amps generated by a commercial VHF Transceiver power supply. To counteract this would require at least 1,000 kg (2,205 lbs) of anode to have any effect on the electrolysis, and probably 10,000 kg (22,050 lbs) to stop it completely, which is often more than displacement weight of the entire vessel / vehicle / installation. It is much better to eliminate the CAUSE than try to cure the effect. Having done so, then anodes can work as they are designed. Anodes are simply ineffective in the presence of electrolysis that is commonly at least ten thousand times stronger. It is best to eliminate the largest cause of corrosion first and then the remaining sources are easier to address.

Electrolysis is more aggressive than rust or galvanic corrosion by at least 10,000 to 1. It is generated by all electrics and electronics. They all require DC current.  A proportion of that current flows from the vessel / installation to the Earth. A ship causing electrolysis in a common conductor such as water will corrode other nearby ships. Electrolysis corrosion can only be measured as current, the cause identified and then eliminated.  Continuous monitoring of all DC sources (batteries) by SeaBis is essential to eliminate ALL causes, as they are often intermittent.


The Cause of Electrolysis

Reference Kelvin Absolute Law:

A battery’s negative terminal is actually at -12 volts and a battery’s positive terminal is at 0 volts. The Earth at  +1.2 volts.  Humidity at greater than 10% is a very good conductor. Therefore, when there is a circuit from the battery negative to the metal of the installation / vehicle / aircraft / ship’s hull or engine, then negatively charged electrons are repelled from the metal to the Earth, carrying your metal with it.  In science class, remember the two bar magnets, when placed with like poles adjacent so electrons adjacent, repelled each other?

All DC returns 80% or more of the current drawn from the battery’s positive terminal to the battery negative terminal. That is why the battery’s negative cable has the same copper diameter as the battery’s positive cable. So if you pass that current through metal in contact with the Earth (via air, land or water) you are causing metal corrosion by electrolysis. See ABYC Wiring Rules at - Menu - Questions.

For example, a starter motor on a medium-size four-cylinder diesel drawing 180 amps will return 180 x 0.80 = 144 amps to the battery via the battery’s negative cable. If the metal is connected to the battery’s negative terminal then a proportion of the current will flow through the metal to the Earth, taking your metal with it.

On a fiberglass boat the same current flows through the propeller, the gearbox and then the engine’s cooling system. The accelerated flow rate in the cooling pump intensifies the electrolysis effect caused by the stray current.

The current flowing to the earth consists of negatively charged electrons. The Earth, at 1.1 to 1.2 positive volts, attracts some of that current. Only one-thousandths of an amp is sufficient to cause enough electrolysis that you can see corrosion in three months.  Accuracy requirement of 10 millionths of an amp with no disturbance of the circuit under measurement is met by SeaBis Master.

Note: Never try to measure this with a multimeter as the battery acid contains hydrogen and may explode. In addition, any reading, if you get one, must be inaccurate. The current must be measured with everything at full power and at an applied voltage (12 or 24 volts) without a current limit in the measuring device below 100 milli amps. The device must not have an effect on the circuit being measured - it must have no internal resistance above 1 ohm.  Multimeters have 500 to 800 ohms. Multimeters measure using 1 volt at one-millionth of an amp so have an error probability of at least 1,000:1. In addition they alter the circuit under test. They will only confuse you while metal corrosion will be on-going.



All metals have a natural voltage. That natural voltage is very low but always present. The natural voltage causes galvanic corrosion. When a copper wire connects two pieces of metal the copper wire transmits the current through itself rather than through the water, thus reducing the effects of galvanic current. However the battery’s positive or negative terminals must never be allowed to make contact with the bonding because electrolysis will increase dramatically causing large and extremely expensive corrosion of the installation's metal.


Step 3: Eliminate the Cause of Marine Corrosion

Marine corrosion is caused by an electro-chemical reaction. When you eliminate the electric current then you eliminate the stray current that causes electrolysis.  We do so by making all metal electrically Open Circuit (disconnected) in full power use, from the World.  Then no current can flow either in or out so there can be no electrolysis, permanently. That is why there has never been a genuine claim for our 8 year money back guarantee.

Please remember it takes 10 cumulative days of stray current  in one year to cause marine corrosion you can see.  So SeaBis  must be permanently connected and How To Stop metal Corrosion complied with.  Then the cause/s of stray current that generate electrolysis are permanently eliminated.

Training at in Products at Training-eliminate the CAUSE of corrosion - free.

Excerpt from SeaBis Master Instructions at in Products at How To Stop Metal Corrosion Instructions.

To go to SeaBis: Do a Google search for SeaBis System.


Procedure to Eliminate the Causes of Marine Corrosion:

The causes are all electrically in parallel (connected together - contact Glen Bishop).  So the procedure is to disconnect circuits until you have a Normal on SeaBis Master.  Then (touch) connect each in turn, leaving disconnected any that cause electrolysis.  Those that are Normal - leave connected. On completion those causing electrolysis are disconnected so will have no power and are easily identified.  Now follow How To Stop Metal Corrosion to complete the diagnosis and repairs. Seabis Master includes free diagnostic and repair assistance.

Products at: at Menu, Products



1: External reference: Proof we are correct, DC (batteries) cause marine corrosion: Wikipedia explanation of the cause of electrolysis

2: External reference: Proof we are correct, article, SeaBis System eliminates the CAUSE of electrolysis: is-electrolysis-eating-your-boat.pdf

3: External reference: CorrosionPedia (Independent corrosion specialists) article: how-to-stop-marine-corrosion-in-3-steps.htm

4: 8 year money back guarantee:  We will either eliminate the CAUSE of marine corrosion or pay you your money back.  How To Stop Metal Corrosion must be complied with - at Guarantee.

5: Testimonials with verification


Contact us:

If you want to comment or feel even slightly disappointed with our products we want you to contact us and we will rectify the matter: Email:

Glen Bishop of SeaBis
To go to SeaBis: Do a Google search for SeaBis System.
Address: 3 Arabian Court, Hindmarsh Valley, South Australia 5211.
Mobile / Cell Australia 61 (0)417 878 773, Office 61 (0)8552 6584, Skype: seabis1

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