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Frequently Asked Questions
Copyright Property of Podean Electronic Industries Pty Ltd.
There is plenty of useful and important information in this section. It is full of helpful hints and will give a clearer understanding as to why stray current has been such a complex and difficult problem to overcome and why a proven solution has taken so long to discover. There are a few technical bits but you don’t really need to know what they mean unless you are particularly interested. I’ve tried to keep them to a minimum.
We guarantee the SeaBis System, when completed, will protect your vessels from electrolysis corrosion.
The SeaBis System will eliminate stray current that is the cause of electrolysis corrosion.
The guarantee is effective for two years.
See www.seabis.com.au/guarantee.html.
SeaBis System design commenced 1993, tested over 15 years with over 200 vessels with 100% success. The proof is in the results. See the following:
1. At www.seabis.com.au/proof.html, Related Links click Photographic Proof SeaBis works
2. And see Testimonials at www.seabis.com.au/testimonials.html .
3. Also see our Test and Active Display Panel at Proof. This aluminum boat is in fresh water with stray current at 1 mA (0.001 amp) in a 12 volt boat, just sufficient to cause SeaBis to flash red, for 3 months. The aluminum from the boat forms an easily visible cloud of aluminum in the water as well as a layer at the tank base and has plated the container with aluminum from the boat.
The sacrificial anode, at bottom left, did not protect the boat. The stray current did not indicate on the anode voltage but SeaBis constantly flashed red. A subsequent test with no stray current caused SeaBis to indicate green and no aluminum to be removed from the boat.
Yes it can. The only method of protection from stray current that will work is to use theSeaBis System to make the boat open circuit (eg. in home terms the electrical plug is pulled out of the wall socket). When every source of DC power (12 or 24 volt batteries) is switched open circuit, permanently, with ALL negative and positive disconnected, no stray current can flow.
If one source (first boat) has the battery negative connected and any other boat within a minimum of 150 meters has the battery negative connected the voltage difference will cause boat to boat stray current – even with both battery positives switched open circuit. Both boats will be damaged by stray current.
Yes. The stray current will increase. Other boats, the mooring and seabed are all causes of stray current. Connecting your boats wet metal to battery negative adds to the sources of stray current and increases inter-boat stray current causing increased electrolysis. The correct method is to use the SeaBis System to make all wet metal open circuit at battery voltage and when all equipment is in full use.
All Blockers are wired in series with the shore mains supply Earth. They only protect the mains Earth, not Neutral or Live or more importantly, all wet metal. So one chance in four. Even then, if type 2. only. The two types are:
- Below $600 each. Containing two diodes that will block DC current up to a maximum voltage of (2 x series diode volt drop of 0.6 volts) 1.2 volts. All voltage above 1.2 volts will allow all current to pass. Your vessels are at 12 of 24 volts.
- Above $600 each. Containing, at 10 times the cost, a capacitor, that will block DC current up to the capacitors rated voltage. Usually 50 volts for this type of capacitor.
In order to stop legal action for liability, electrical authorities throughout the First World are connecting the mains Neutral in parallel with the mains Earth. This stops the Neutral becoming live. So incorrect wiring will instantly blow the fuse or trip the breaker. Thus the Neutral places an electrical short circuit across the Blocker. That is why we are seeing a very steep increase in stray current electrolysis. I regularly get complaints “I have a new Blocker and still get electrolysis”.
Semi technical stuff:
The Blocker, if it were not shorted by the Neutral or Live and contains a capacitor, could only block the Earth. It cannot block the mains Neutral, Active or more importantly the water path to the seabed, other vessels and Marina. The water path is much more prevalent as it is connected every hour of every day, permanently. The shore path is only connected while actually plugged in. If you have any doubt, use of the SeaBis Marina System will INSTANTLY and accurately prove all vessels within at least 150 meters are electrically connected together by the water.
The SeaBis is
stray current meter controlled by a microprocessor. It is instantaneous and very accurate. The SeaBis System, assuming you follow our Installation Instructions and Process of Elimination, will eliminate the cause. A positive solution. Our guarantee is here.
A little truth:
In addition, my copy of AS/NZS 3004:2002 is markedly different to the brochures used for Blocker advertising. The AS/NZ Standard provides 3 Marina wiring alternatives. One of which mentions a Galvanic Isolator. None mention a Blocker. Copy available. Galvanic explanation: The VOLTAGE generated by differing metals. At a maximum this is one volt. Given your vessel at 12 or 24 volts stray current is at least 1,000 times, often 10,000 times more ferocious than Galvanic Voltage.
Install the SeaBis System and complete Process of Elimination Instructions to protect your vessel from stray current electrolysis. The hull and wet metal will be electrically open circuit (in home terms the electrical plug is pulled out of the wall socket). Now no damaging stray current can flow through your vessel, irrespective of the cause.
Stray current flows through the water and seabed. It is dependant on your vessel, those around you, the rate and direction of current flow and the shore mains power supply. It is caused to flow via your vessel by parallel problems that are all rectified by the SeaBis System. Obviously nothing can monitor that stray current unless it monitors the wet metal of your vessel for stray current - not voltage. if your protection system attempts to impress current in the opposite direct to the stray current then it will have to continually monitor the stray current to determine the amount to impress to cancel the stray. With all my knowledge and experience I think this is impossible.
The Bonding System connects all wet metal together. It tries to reduce inter-wet metal voltage and so reduce galvanic corrosion. The inter-wet metals maximum voltage is 1 volt. Your vessel is at 12 or 24 volts. So stray current is, at an absolute minimum 12 or 24 times stronger than the inter- wet metal natural voltage. Stray current is commonly 1,000 to 10,000 times more ferocious. Completing the SeaBis System will eliminate the stray current. If you connect SeaBis Sensor, the green/yellow to the bonding, SeaBis will indicate the stray current through the bonding.
The SeaBis System will remove all stray current so protecting your vessel. SeaBis is a measuring tool for stray current. It is very easy to install and uses a traffic light system to indicate levels of stray current. We then disconnect equipment until SeaBisindicates green – no damaging stray current. The Process of Elimination Instructions supplied with SeaBis explain how to eliminate the cause. On completion no damaging stray current can flow so there can be no electrolysis.
Using the analogy of the globe in the ceiling light socket. If the wall switch to the lamp (globe) is on and no lamp fitted, voltage is present at lamp socket but the globe does not light. No current flows through the globe even though voltage is applied. Current through the globe equates to wet metal / hull (stray) current.
It is current that flows through the lamp that causes it to light and current through wet metal / hull / propeller that is the energy that does the damage. Measuring voltage does not indicate the current that actually lights the lamp or does the damage. We connect to any wet metal, measure (stray) current and eliminate it. Use SeaBis Marina Maintenance Kit to prove this to yourself.
Basic Process of Elimination:
These and Process of Elimination Instructions all depend on the use of SeaBis. Save yourself much heartache and costly repairs by completing the SeaBis System and Process of Elimination Instructions. I developed SeaBis because I was unable, despite owning of $100,000 of test equipment, having the equivalent of 2 degrees in marine electronics and with 25 years relevant experience, to find the initial cause of stray current electrolysis. My new equipment finds the cause. I proved my new equipment on over 200 vessels over 15 years. So now I can confidently guarantee the SeaBis System. For technical explanation why a multimeter can not tell you the truth scroll down this page.
Progressively disconnect ALL equipment at positive AND negative, labeling each wire and connection to ensure certainty of correct reconnection, until Normal – illuminates. The reason for pairs of wires is the engine cooling water, in or out of the sea, can complete a path for stray current via the one wire left connected. It is easiest to work from Normal, adding suspect pairs of wires so identifying the cause/s.
Reconnect one pair of wires at a time until other than Normal illuminates Disconnect the pair of wires that caused other than Normal and leave it disconnected.
When ALL wiring has been tested you will be left with one to four pairs of wires that cause a fault indication. Follow those wires to equipment then consult Process of Elimination Instructions supplied with SeaBis for rectification of defects.
If still unsure, make absolutely certain you have missed no wiring before you contact us.
This latter point is often the cause. I.e. On boats, the main breaker switch is normally after the bilge pump, battery charger and fridge. So opening the main breaker switch does not disconnect those equipments. Bilge pumps and battery chargers are common causes of stray current electrolysis. In addition this switch only breaks the battery positive, not the negative.
When the whole vessel indicates Normal, with all electrics and electronics fully operational, your vessel is immune to the stray current that causes electrolysis corrosion.
Now plug in the shore. If SeaBis indicates stray current then disconnect shore powered equipment in the same manner as you did the DC (battery power). I have never known this to fail. However, if you prefer contact us for an isolating transformer. Read the linked file, before purchasing an Isolation Transformer. They should only be used, with caution, complying with all the warnings and as a last resort. An Isolation transformer breaks the earth and neutral DC link to the shore. It does not break the stray current link through the water.
A Normal indication, (at less than 0.5 mA for 24 volt vessels and 0.25 mA for 12 volt v4essels), is caused by stray current being too low to cause damage).
Glen Bishop of SeaBis.
Stray current will flow from your boat to a all boats within at least 150 meters via the seabed / another boat / mooring / pylon where only 0.5 volt difference exists. The seabed is at 1 volt. Your vessels wet metal at 12 or 24 volts. This is easily proven using the SeaBis Marina Maintenance System. The SeaBis System electrically isolates your boats wet metal so there can be no stray current. When there is no stray current there is no electrolysis. Your vessel is immune to all others.
Problem fixed.
SeaBis monitors and indicates both AC and DC current. SeaBis is connected to a DC power source such as batteries. The reason is DC current flows in one direction only so will transport metal particles in that direction. AC current reverses its direction every half cycle (60 times 2 or 50 times 2 shore power frequency) so every 120 or 100 times per second. So a particle removed in the first half cycle will be replaced in the second half cycle. SeaBis is connected to 10 to 30 volts DC only. Are you O/K with this explanation? Please contact me if any uncertainty lingers.
Stray current in the water looses 10% of its ferocity in 100 meters. So a source of DC current on the first boat will cause stray current on every boat within at least 150 meters. It will also conduct via shore supply were the source is not isolated and the SeaBis System not used (Does this answer your question?). The SeaBis System will protect a boat from ALL stray current. All its wet metal will be electrically open circuit.
Marine isolated starter motors, alternators, winches etc have battery negative and positive 10 millimeter wires to the battery. The body of the starter motor etc is isolated from both battery wires. Marine electrically isolated starter motors, alternators and senders all have connections isolated from their metal body so are isolated from all wet metal.
If there is only 1 large wire to the battery the starter motor etc can not be isolated. They are using the engine or winch body as common negative so will generate stray current.
The switches supplied with SeaBis are good quality with written full specifications. They will last whereas cheaper types will fail.
Switch Choice:
Foe engine sizes up to a 4 cylinder petrol or diesel the choice is simple. The switch supplied as standard with the SeaBis kits - 275 RMS amps / cranking or peak 1250 amps.
As engine size increases so does starter motor current requirement. So the switch must have a higher capacity: The SeaBis OPTO0811 has capacity 600 RMS amps / cranking or Peak 2500 amps for 10 seconds.
For massive engines with a starter motor weighing 50 Kg or more, the engine manufacture supplies a suitable rated contactor. Ask your electrician.
Automatic Switches:
The SeaBis Automatic Isolator will protect your vessel from starter motor / winch any other large source up to 4 cylinder diesel / petrol by isolating the source when not in use. Click here.
RMS or Peak ratings? RMS is the continuous rating. 30 seconds is continuous. Peak is very intermittent at thousandth of a second. Often 5 to 10 times the RMS. For the same switch under different conditions.
A 1 Kilogram (1,000 grams) sacrificial anode produces 1 micro amp (0.000001 Amp) of current at a voltage of one volt. A boat uses 12 or 24 volts – 12 or 24 times the anode voltage.
Stray current is 1,000 to 10,000 times stronger than the anode current and to the seabed, other boats, mooring, pylon and wharf. Stray current will loose 10% of its ferocity in 100 meters.
The stray current will swamp the good anode, destroying the anode and it’s good effects. In addition, the anode current is in a different circuit, so depending on current flow direction, may do no good whatsoever. So adding additional anodes is wasting money and not protecting the vessel.
The only method to remove stray current is to use theSeaBis System to remove the cause and allow sacrificial anodes to work correctly, so protecting the vessel.
Regretfully, no. This is why we built theSeaBis System. Mutimeters use very low voltage and current so, while they will attempt to measure ohms, they are operating at about 1 volt with a millionth of an amp. This causes an error probability, on 12 volt systems (12 volts minus 1 volt divided by 12 as percentage) of 92%.
Error probability on 24 volt boat is 96%. For no error probability use SeaBis Systemas our Installation and Operation, Process of Elimination Instructions.
Again regretfully, no. Because of its internal design, the multimeter will show a full fault if stray current is one millionth amp. There is nearly always stray current of at least one millionth amp. At one millionth amp (0.000001 amp) stray current cannot cause damage. SeaBis indicates Normal below 0.5 milliamp (0.0005 amp) stray current.
Again regretfully, no. This is a potentially lethal mistake. Assume there is a partial or complete stray current from battery negative to hull. If a multimeter, on mA (milliamps) or A (amps) range is connected between battery positive and hull it will complete a dead short across battery, through the leads in your hands, and attempt to discharge the battery in less than a second. Apart from damaging the multimeter, this could result in burns from leads or a potentially lethal battery explosion. Never carry out this procedure. It has a history of severe burns and death.
Again regretfully, no. This is another potentially lethal mistake. Assume there is a partial or complete stray current from battery negative to hull. If a milliamp meter, is connected between battery positive and hull and it has been dropped or any other fault developed, it cannot tell you the truth. It will complete a dead short across battery, through the leads in your hands, and attempt to discharge the battery in less than a second. Apart from damaging the milliamp meter, this could result in burns from leads or a potentially lethal battery explosion. Never carry out this procedure. It also has a history of severe burns and death.
Again regretfully, no. This is another potentially lethal mistake. The same reason as milliAmp meter.
This produces much more voltage than your boat can tolerate and will result in expensive damage.
Stray current, often 1000 to 1 ratio greater than the anodes is destroying them.
Stray current supplied by batteries is damaging the equipment / hull / propeller. UseSeaBis System to eliminate the cause/s of stray current.
Elevated water temperature, salt and fresh, attracts stray current more so than cooler water. Use SeaBis System to eliminate the cause - stray current.
Yes! A wire as thin as a hair will easily conduct enough stray current to cause serious electrolysis corrosion in 3 months. The small auxiliary / bridge battery, typically for starting outboard engine or VHF / HF SSB transceiver is often overlooked, with resulting stray current causing electrolysis damage.
It takes as little as one thousandth of an amp of stray current to cause damage. A very small (very small car size) battery holds 150 ampere hours (150 hours at 1 amp). This is more than 1000 times that necessary to cause damage.
Insertion rubber, Teflon / plastic bread board cut to shape or, if in DRY environment thick wood. Wet wood becomes a conductor as it ages.
From 2 hours to 2 days. Longer, for a large vessels with multiple causes. There is just no way to tell how long until SeaBis System Process of Elimination Instructions are completed. It is very much cheaper to remove causes of stray current than the effects. Effects include damage to hull, propeller, fresh water tanks, manifolds, anodes, any metal in contact with water.
On a 24 volt boat, Normal at less than 0.5 milliamp, Caution at 0.5 to 1.0 milliamp, Serious at 1.0 to 2.0 milliamp and CriticalFlashing red at greater than 2.0 milliamps. (0.5 milliamp is 0.0005 amp). For 12 volt boats, halve these figures as current concentration is much greater due to smaller wet metal surface area. See Download of SeaBis Test and Display Panel for the affect of 2 milliamps for 3 months. The white cloud is aluminum from the boat.
Yes. The cause and effect from boat to boat to pylon to seabed is always complex and cannot be easily identified. If your SeaBisindicates Normal, your boats wet metal is electrically open circuit, no stray current can flow, there can be no electrolysis and sacrificial anodes will work as designed.
Yes, but only marginally so. The real cause is warm water. If the water temperature is increased then increased stray current will flow. This is because electrolysis is a chemical reaction and reaction speed increases with temperature. The salt marina with static water is only marginally worse than the fresh water marina with static water.
Adjacent boats, wharf pylons and the seabed all contribute to stray current with the only solution being to use the SeaBis System and so make the equipment / hull / propeller / rudder / engine cooling system electrically open circuit. Then no stray current can flow and there can be no electrolysis.
With SeaBis monitoring your boat at all times.
The sacrificial anodes can then work correctly.
Yes. However you must be plugged into the shore and have no SeaBis System. Without the SeaBis System, shore power can connect a DC (battery) cause of stray current on another boat to yours. In practice the DC source (12 or 24 volt batteries) is connected by at least the negative every hour of every day - permanently.
Mains voltage shore power is not connected permanently so can not cause as much damage as boats DC. In addition AC reverses current direction every 1/100 second. So if it removes a metal particle in the first 1/100 second it will replace it in the second 1/100 second.
A DC (battery) path on another boat, via an AC (shore power) connection, where the SeaBis System is not installed, will cause stray current while shore power is plugged in. To eliminate this stray current use the SeaBis System to remove stray current paths from your vessel, then plug in shore power and see if Seabis indicates stray current. Remove the mains power stray current by progressively disconnecting equipment - the same as with the battery powered equipment. Only if you must use AC powered equipment that you cannot isolate, consider an isolation transformer. You probably will not need an Isolation Transformer but if you do, read this file first, this is absolutely imperative, click here..
Yes. The only certain method to stray current proof your vessel is to use the SeaBis System to make the hull open circuit. Stray current cannot enter your boat nor can your equipment / boat cause stray current.
Shore AC can only cause stray current when plugged in and SeaBis System is not applied. First clear the vessel of stray current by using the SeaBis System then plug into the shore, if SeaBis indicates stray current then contact us for an isolation transformer.
Your car is sitting on rubber tires so insulated from the earth. Your boat sits in water, both fresh and salt water provide a very good contact to the seabed so conduct stray current between boats, seabed and mooring.
Defiantly not. SeaBis has 3 wires, battery positive, battery negative and wet metal - engine or hull.
90% of owners complete Process of Elimination themselves. 5% contact us then complete themselves. 5% get their maintenance man or electrician to complete the Process of Elimination instructions supplied with SeaBis..
We are compiling a list of marine technicians / electricians and will supply on request. If you would like to be on this list then please contact us. While some opt to get their electrician to complete the repairs many owners and professional fishermen do so, successfully, themselves.
We will cooperate with your chosen method. We can also talk / email you through the process.
If needed, we will assist with advice based on 15 years of experience with 100% success. We can attend at your request.
Glen Bishop of SeaBis
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