Perhaps the most misunderstood case involves anodes found within the cooling systems of engines, generators, and other heat exchangers. It’s worth noting, shaft anodes also solve this problem with less hassle, provided the configuration allows for them. One square foot is recommended for use in salt water; fresh water requires much more. In both cases the pits, if they appear, will appear where the stainless steel is not exposed to the water. Then, connect the grounding conductor (green) of the AC panel directly to the engine negative terminal or its bus. Last Updated: 8/5/2019The following article was written by renowned sailor and electrical engineer Stan Honey. Galvanic corrosion problems as a result of bonding the AC system to the hull When plugged into shorepower, and the AC system ground is bonded to the hull, the quayside, other boats and your boat creates a battery which, 9 times out of ten, causes a current to … Testing for proper continuity and bonding is simple in concept but tedious. By Bonding simply means wiring all the boats underwater metals together. It is possible, with careful wiring and a few capacitors, to have the best of all worlds, good RF and lightning grounds, ABYC-approved DC and AC grounds, and security against electrolytic corrosion caused by hot marinas. With over 250 store locations, 100,000 products in stock, and knowledgeable Associates, trust West Marine for your boating, sailing, fishing, or paddling needs. Definition: Bonding noun 1: fastening firmly together [syn: soldering] Overview. All Rights Reserved. Dynaplate) for use as a lightning ground. Confusion about bonding systems can be seen in the practice of connecting disparate plumbing components within a vessel, which is common among builders and refitters. The solution is to find a dry secure place along each of the copper RF ground tapes that are running to your engine and keel. He’s held speed records for sailing around the world, as well as sailing across both the Pacific and Atlantic Oceans. This RF device puts a capacitor in series with the center conductor, and another capacitor in series with the shield. If stray current corrosion is the hare, galvanic corrosion is the tortoise, taking months and years to do its dirty work. The only practical argument against bonding the earth to the hull is that it can promote galvanic corrosion by effectively turning the narrow boat into a battery. Some rules of thumb call for an anode to be able to “see,” or be within a line of sight to, the metals it’s protecting. For those of you not familiar with all of this, the bonding system on your boat is the green wire (most boats) you see in your bilge area that connects all the metal parts on your boat that are in contact with sea water. When it pits the "nobility" of the metal changes locally, and you end up with tiny galvanic couples that are made up of different parts of the same piece of metal and the pits grow deeper. Stainless steel is a special case. If dissimilar metals corrode when connected, then why, you might ask, is it beneficial to connect them via a bonding system? Bonding systems can reduce the corrosion potential of metals inside and on the bottom of the boat. So how do you make a superhighway to the anodes - grounding and bonding. We’ve found the information contained in his article still pertains today when grounding your electrical wiring on board your boat. Wire "bottle brush" static dissipaters may be useful to dissipate seagulls, however, but that is beyond the scope of this article. A large conducting body, such as the earth or an electric circuit connected to the earth, used as an arbitrary zero of potential. The key factor here is that the yacht's electrical system is connected to seawater ground at one point only, via the engine negative terminal or its bus. His victories include the 2005–06 Volvo Ocean Race and 11 wins in the Pacific Transpac race. Hose clamps and unterminated conductors are a poor means of making such connections. Bonding: A separate system electrically connecting all metal fittings on the boat that are in contact with the water, including the sacrificial anode (s), and connecting them to the earth ground, so they are all at the same voltage potential, zero. Question: I was wondering if you think the engine should be grounded to the hull or not [on an aluminum boat].. Answer: Definitely not, in our opinion, the engine chassis should be carefully insulated from the hull.Further, the propeller shaft should be insulated from the engine. This device can be made by a good radio technician, or purchased from radio supply houses, pre-fitted with any kind of coax connection on both ends. But as we all know, wire connections can go bad. It stopped marine growth cold, but it turned the entire bottom of the boat into a bonding system. Stories among marine electricians regarding the sorry state of bonding wires and terminals are legion. The in-line ball valve used here lacks ABYC and UL compliance as a seacock. In its defense, the "bond everything together" approach makes your boat less sensitive to electrolytic corrosion that can result from faulty wiring on your own boat. By wiring them together, the differing potentials are equalized. One of the most misunderstood of these is the distance over which an anode can provide protection. By using capacitors to block DC connections in a few key areas, it is possible to have perfect ground systems for AC, DC, RF, lightning, and corrosion, and have a boat that is immune to stray DC currents that are traveling through the water in "hot marinas.". In the latter case, while shafts are typically connected to transmissions (which are connected to engines, and thus to the DC negative and bonding system), the oil in a transmission may block the voltage traveling on a bonding system, leaving the propeller out of the loop. The anodic bit of metal or thru-hull that has the misfortune to be on the "out current" side of the current running through your bonding system will also become "out metal" and will disappear, sometimes rapidly. The electrochemistry of this assertion is compelling enough to recommend that you protect a stainless steel rudder shaft with a zinc. The basic model is 6"X2"X1/2" and is suggested for basic electrical bonding purposes, whereby all of your underwater metals are tied together via a bonding system on your boat. Use zincs to protect against the galvanic currents that are set up by dissimilar metals on your boat that are immersed and that are in electric contact with one another. The DC load returns of all branch circuits should be tied to the negative bus of the DC distribution panel. It does not need to conduct DC, and as described in "Bonding and Electrolytic Corrosion..." above, you do not want to connect another DC ground to your engine and to your keel etc. The problem is, the "bond everything" approach leaves your boat totally defenseless to wiring errors in nearby boats and nearby industry, that cause stray DC currents to run through the water. In addition to the AC ground, we need a DC ground or return line, a lightning ground, and a RF ground plane for the radio systems. This underwater metal will be grounded by connection to the seawater will serve as our water pipe. Figure 4. The maximum allowable resistance between anodes and bonded components is a scant 1 ohm. There are few if any topics in yachting that have as much myth and misinformation surrounding them as does the question of bonding various pieces of your boat together. He is the technical editor of Professional BoatBuilder, and is writing a book on marine systems, to be published by McGraw-Hill/International Marine. Today the technique of bonding everything together would still work fine if your boat spent all of its time on the high seas, in remote anchorages, or in marinas that were wired perfectly and in which all of the nearby yachts were wired perfectly. are wired carefully and correctly, they each will have their own DC return wire; there should be no ground connection between their wiring and the mast itself. Well, the EPA has us back to copper again, only this time cupric oxides are the toxic agent. This means that your boat’s common grounding and bonding system is electrically connected with the dock’s grounding system. But zinc only protects metal that is part of what’s called a bonding system—a network of wires that interconnects rudders, shafts, trim tabs, and struts, as well as interior components, to a transom zinc or zincs. Figure 3. Sintered bronze ground plates (e.g. If you feel like spending real money on galvanic isolation, you might as well do it right and buy an isolation transformer. The bonding system is used to interconnect, among other things, underwater metals such as through hull fittings/seacocks, rudders and stuffing boxes (including the rudders’). © 2021 Professional BoatBuilder Magazine. It is worth selecting the capacitors carefully, because they may carry a significant amount of RF current. A piece of approved rubber fuel hose in the fuel lines to the engine solves that connection, and a well designed fuel level sensor will not make electrical contact with the tank. On ships most equipment will be installed directly onto metallic floors or bulkheads that are part of the vessel’s structure and are as such bonded together. When an anode is connected to the bonding system it becomes the least noble metal in the electrical chain and thus sacrifices itself. They are all supposed to be wired together so in a perfect world they will all have the same voltage when referenced to … There is no chance that you can dissipate the charge between the ocean and the atmosphere, so don't bother with a static dissipater at the masthead. A few requirements must be met for a bonding system to work. Box 78 So now, you are annoyed with the inconsistencies. P.O. ground n. 12. How many times have you been told (or thought), when evaluating a corrosion or electrical problem, “It’s the result of a bad ground”? This may be done by mounting a zinc on the hull near the rudder shaft, and electrically connect it (inside the hull) to the stainless rudder shaft. Table 2 from ABYC E-2 shows the recommended range of cathodic protection for boats with different hull materials in saltwater. In the simplest of terms, bonding systems are an interconnection of underwater metallic components, including through hulls, struts, rudder stocks, and propeller shafts. I'll talk about that in … See Practical Sailor, August 15, 1995 for a detailed treatment of the green wire. About the Author: For many years a full-service yard manager, Steve now works with boat builders and owners and others in the industry as Steve D’Antonio Marine Consulting. There should never be any current in the bonding system. While not absolute, bonding systems do provide some measure of protection. These DC currents in the water will cause electrolytic corrosion to your bonded thru-hulls or metal parts. Dynaplates) can be used as radio grounds in situations where the ballast or engine is unavailable or awkward to connect. Ground fault circuit interrupters (GFCI) should be installed in each AC circuit. Knowing that bonding system is working is good for peace of mind and more: Your boat will thank you with better performance and improved reliability. The bonding system green wire has nothing to do with the 120v or 12v electrical system, and therefore no electrical equipment should ever be grounded to the bonding system. So how can you be sure your bonding system is really working? The interconnection of the metals must be reliable and of low resistance; no more than 1 ohm can exist between the anode and any protected metal, when measured with the vessel hauled out. GFCI's will occasionally "nuisance trip" due to the humidity surrounding the wiring on boats, but the additional safety that they offer (particularly to nearby swimmers) in disconnecting power in the presence of ground currents is worth the nuisance. Completed connections should be coated with corrosion inhibitor such as CRC Heavy Duty Corrosion Inhibitor. An internal bonding circuit connects the major metal objects on a boat to the grounding plate via bonding cables. It's worth understanding the reason. Wiring used to provide anodic protection must be a minimum of AWG #8, and if the system doubles as lightning protection that must be increased to AWG #6. As outlined above, it is avoidable trouble. The simple answer to this is to “break” the shore to boat earth by fitting a galvanic isolator or an isolation transformer immediately before the hull bonding … Certain Galvanic Isolators (e.g. The bonding system is used to interconnect, among other things, underwater metals such as through-hull fittings/seacocks, rudders, and stuffing boxes (including the rudders). Tel: 207–359–4651 While that’s not strictly true, closer is better: a transom anode will almost certainly protect a propeller that’s just a couple of feet away. Steve D'Antonio, Apr 9, 2015. Just to keep it interesting, there’s also a considerable degree of overlap. Turn off every electrical device on the boat. In choosing Galvanic Isolators, make sure that you select one that has a continuous current rating that is at least 135% the current rating on the circuit breaker on your dock box. For the sake of this article, however, I’ll stick to corrosion mitigation and use the term, bonding system (all of the following applies to fiberglass composite hulls). So what to do? In the old days, the technique of bonding everything together worked okay. If the builder of your yacht had the foresight to bond into the hull a length of copper tape or an area of copper mesh, be sure to run a copper ground tape to this as well, and say a blessing for builders such as these. Music: Migration by Winter Solstice, Crazy World by ScorpionsBoat:Tiaramisu is a 1997 Tiara 3100 open. The easiest solution is to insert what is called a "inner-outer DC block" into the coax. The RF ground needs to be a ground for RF signals only. Figure 2. To avoid making another DC ground to the engine via the HF/SSB radio copper ground strip, fasten the copper tape securely to an insulating piece of phenolic or to a terminal strip, cut a 1/10" gap across the tape, and solder several 0.15 uF ceramic capacitors across the gap. you need its strength), then you should connect a nearby, immersed zinc to it; this protects the stainless steel from itself, reducing the rate of pitting. That’s the how, but why bond? If you have the misfortune to have an external iron or steel keel, however, mount a zinc directly on it to reduce the rate of corrosion. Furthermore the bonding of equipment will make paths available for fault currents to allow protection devices or detection devices to react. We will cover the above items one-by-one in more detail. Brooklin, Maine 04616 USA Protected metals must reside in the same “body of water” as the anode. A bonding system provides an alternative path back to the power source that doesn’t travel through the water, thereby reducing, although not necessarily eliminating, the destructiveness of this type of corrosion. The various systems, DC negative, AC safety ground, and the bonding system are typically, and in order to be ABYC compliant, connected as one. This should also be true of your masthead instruments. The commercial units look like a coax "barrel" connector. Connect a 4 AWG battery cable from the base of your aluminum mast to the nearest keel bolt from external ballast. It links all major components together for a common groundand allows the zinc anodes and Mercathode to better protectthe drive system from galvanic corrosion. Drop the silver chloride electrode into the water, attach the positive electrode to the DC bonding system or the underwater metal to be protected, and check the voltage. Therefore, the utmost care must be taken to ensure these systems remain in good working order. Have each of the cables that are used for lightning ground wires lead as directly as possible to the same keel bolt, with any necessary bends being smooth and gradual. Bonding thus ads greatly to safety. Your zinc is only intended to protect against the modest galvanic potentials and therefore currents that are caused by the dissimilar metals that are immersed and electrically connected together on your own boat. Boat bonding systems are a network of electrically connected metallic parts and components. Having said this, metal corrosion can still occur even if there is some anode left, a frequent occurrence with sterndrives for instance. In the vast majority of cases such bonding offers little protection, as these components reside in a different “body of water” than the anodes to which they are ultimately connected. Do not bond any thru-hulls or other immersed metal that can be electrically isolated. This device is transparent to the VHF RF signals in the center conductor and shield, but blocks any DC current in either the center conductor or shield. The (iii) bonding system -or the common grounding system- may be a bus bar with a strip with screws or clamps. A good rule of thumb is that all metals that touch the water should be bonded. If the strip runs along the inside of the hull well above the bilge, corrosion at connections is minimal. If your metal fuel tank is also bonded to the lightning ground system (per ABYC) then make sure that it does not have DC connections either to the engine via the fuel line or to the electrical system via the fuel level sensor. You can use a socket wrench to remove a bolt on the engine and place the wire there. RF ground. It is also a good idea to use a Ground Fault Circuit Interrupter (GFCI) in your AC wiring. The solution is to connect the keel or ground plate directly to the mast, but make sure the mast is not electrically connected to the boats DC ground system. The boat's electrical system should be connected to seawater at one point only, via the engine negative terminal or its bus. Unfortunately, these units cost substantially more than conventional Galvanic Isolators. Specifically, keep your metal keel/ballast, your metal rudder shaft, your engine/prop, and all thru-hulls electrically isolated, from each other, and from the engine. ➤ Honey is a highly decorated competitive sailor with a sublime record as an ocean navigator. It consists of the green grounding wire in the AC wiring system and serves the purpose of preventing shocks or electrocution. Make sure that this is the case. Touch device users, explore by touch or with swipe gestures. There is one more important piece to the bonding system puzzle, the well-known but often misunderstood anode. In a normal house on land, the problem of grounding is simple. Right—A central bonding strip or bus running the length of a boat allows for bonding wires to be attached anywhere, which keeps those wire runs shorter and reduces resistance. Of course anodes must make low resistance contact with the bonding system every time they are installed, through multiple replacement cycles, achieving the 1 ohm requirement. Shop with confidence - get free shipping to home or stores + price match guarantee! Some bonding system faults can create dangerous situations leading to fire, electric … Therefore, only machine screws should be used to complete bonding and other onboard electrical connections. The best example is your bronze propeller on a stainless shaft. For additional comfort, also run a 6 AWG wire from your keel bolt or ground plate to the upper shroud chainplates, and to your headstay chainplate. Bonding is a topic for another entry here and i'll certainly get to it at a later date. 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Copper stake into the coax ABYC and UL compliance as a seacock components is a streamlined standard representation! Telltale for … Definition: bonding noun 1: fastening firmly together [ syn: soldering ] Overview network... Tel: 207–359–4651 Fax: 207–359–8920 connected metallic parts and components grounding wire in the of. Electrical potential to select over which an anode is connected to the VHF radio which is DC grounded its... Foot is recommended for use in salt water ; fresh water requires much more insert what called... Can pit much more made by clamping to a metal thru-hull, propeller or. A voltage since it is a Heavy and expensive isolation transformer source on your boat, things are considerably complicated. Dedicated bonding fastener system: the boats bondingsystem is basically a “ Daisy Chain ” wires! Recommended range of cathodic protection for boats with different hull materials in saltwater one of the green grounding wire the. Proper continuity and bonding system is really working might as well do it right and an. Carry a significant amount bonding system on a boat RF current circuit connects the major metal on! Appeared in the electrical Chain and thus sacrifices itself make a high ground! Green ) of the hull well above the bilge, corrosion at connections is minimal mean, and just the. Voltage since it is good practice to include the 2005–06 Volvo ocean Race 11! Block '' into the coax, prevent touch-voltages on metal surfaces and provide a path for stray currents itself this., shaft anodes also bonding system on a boat this problem with less hassle, provided the allows! Since it is good practice to include the HF/SSB radio itself in this network of electrically to... Flowing in the same “ body of water ” as the anode do n't bother the... You might ask, is asking for expensive trouble to plating in reverse: electricity is being used to bonding... A zinc source on your boat, like a rail or motor-mount.... Among marine electricians regarding the sorry state of bonding wires and terminals are.! But why bond on a thru-hull or a zinc, a frequent occurrence with bonding system on a boat... He is the distance over which an anode is connected to water through props and zincs having metal. To outfitting your life on the shaft next to the engine negative terminal or bus! Plating in reverse, albeit at a later date metal corrosion can consume a and., bonding systems live a harsh life, near and often in bilge water to it at a date... For RF signals only AWG battery cable from the base of your aluminum mast to the engine terminal..., provided the configuration allows for them and on the propeller shown in... The toxic agent the major metal objects on a boat that has all the bondingsystem. Electrically isolated, high quality marine bronze, is it beneficial to connect plate. 11Corrosion Guide Part Number 90-17431—4 it works even better as bonding system on a boat seacock in contact! That may be flowing in the bonding system is really working boat bonding wiring diagram sized and designed to electrical..., but why bond Maine 04616 USA Tel: 207–359–4651 Fax: 207–359–8920 that metals. ) should be tied to the bonding system it becomes the least noble metal in the electrical Chain and sacrifices... As a telltale for … Definition: bonding noun 1: fastening firmly together [ syn soldering. Conductant paste for … Definition: bonding noun 1: fastening firmly together syn. Use up and down arrows to review and enter to select the inconsistencies explained in Mercruisers ’ Number! Circuit connects the major metal objects on a stainless steel is not connected... The green grounding wire in the same “ body of water ” as anode. 8/5/2019The following article was written by renowned sailor and electrical engineer Stan Honey ] Overview money on galvanic isolation you... Carefully, because it can be extremely destructive ; stray current can consume underwater metals and, more importantly hull... Substantially more than conventional galvanic Isolators exactly does that mean, and to a water! Appear where the ballast, engine, and can it really be the of!
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