Once the DC connection from the mast to the VHF is broken, check for any other connections with an ohmmeter, and straighten out any other wiring errors or unintended connections. They are all supposed to be wired together so in a perfect world they will all have the same voltage when referenced to … Finally, in addition to lacking compliance with ABYC standards, tapping screws are notorious for loosening, particularly if driven into wood or fiberglass, when used to secure electrical ring terminals. Fortunately, it works pretty good. Your zinc is incapable of supplying enough galvanic potential to protect against substantial DC currents that may be flowing in the water. 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. If your bits of immersed metal are bonded, the electric current will take the lower resistance path offered by your boat in preference to the water near your boat, and the current will flow into one of your bits of metal, through your bonding wires, and then out another bit of metal. This often neglected system is what is supposed to keep all of the underwater metal components at the same electrical potential. Touch device users, explore by touch or with swipe gestures. Having said that, the misunderstanding is not surprising: Bonding systems are covered by two ABYC standards, E-2 Cathodic Protection and E-11 AC and DC Electrical Systems, which have different goals, corrosion mitigation and electrocution/fire prevention, respectively. What parts need to be bonded? If your GFCI starts to nuisance trip, it is probably a very good idea to track down and clean up your damp wiring in any event. An isolated bronze thru-hull doesn't need protection because it is not in electrical contact with another immersed dissimilar metal. Run copper ground tape from the tuner to the stern pulpit/lifelines, to the engine, and to a keel bolt. The RF ground needs to be a ground for RF signals only. 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. If stray current corrosion is the hare, galvanic corrosion is the tortoise, taking months and years to do its dirty work. 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. 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. P.O. They cannot protect underwater metals and, more importantly, hull anodes cannot protect gear filled with raw water within the vessel. 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. 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. Unfortunately, these units cost substantially more than conventional Galvanic Isolators. 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 … A good rule of thumb is that all metals that touch the water should be bonded. In seeking a return path to its source it can be extremely destructive; stray current can consume a propeller and shaft in days. If your bits of immersed metal are bonded, the electric current will take the lower resistance path offered by your boat in preference to the water near your boat, and the current will flow into one of your bits of metal, through your bonding wires, and then out another bit of metal. Your VHF doesn't need to use the ocean as a counterpoise, so here we are dealing only with the ground needed for your HF/SSB radio. Having said this, metal corrosion can still occur even if there is some anode left, a frequent occurrence with sterndrives for instance. 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. Also, the motor, … 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. A few requirements must be met for a bonding system to work. It appeared in the October 15, 1996 issue of Practical Sailor magazine. The easiest solution is to insert what is called a "inner-outer DC block" into the coax. By wiring them together, the differing potentials are equalized. 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’). West Marine is committed to outfitting your life on the water. So how do we keep the keel or ground plate electrically isolated as required in "Bonding and Electrolytic Corrosion..." above? Don't bother with the backstay if it is interrupted with antenna insulators. When installing or augmenting bonding systems, connections should be made using heat shrink terminals, and conductant paste such as Thomas & Betts Kopr-Shield. Learn how to check the system here. 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. It is worth selecting the capacitors carefully, because they may carry a significant amount of RF current. While this interconnection method works well, it has limitations. 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. Quicksilver) include large capacitors in parallel with the isolation diodes, which in certain situations theoretically provide better galvanic protection. Do not rely on a thru-hull or a sintered bronze radio ground (e.g. Connect one end of the wire to a bonding ground source on your boat, like a rail or motor-mount bolt. Bonding thus ads greatly to safety. They used #8 wire for the system and did a nice and tidy job of it. This is why anodes, which could be zinc, aluminum, or magnesium, depending on whether the hull is in salt, brackish or fresh water, often include the prefix “sacrificial,” as they sacrifice themselves to protect the other interconnected metals, known as “cathodes.” It’s an approach often referred to as, “bond and protect.” When they are depleted, the next least noble metals will begin to corrode. 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. Bonding systems also mitigate galvanic or dissimilar metal corrosion, which occurs when dissimilar metals are in contact with each other, either directly or via wires, and immersed in an electrolyte (seawater in these cases), establishing a galvanic cell or battery. He’s held speed records for sailing around the world, as well as sailing across both the Pacific and Atlantic Oceans. Given that you have grounded your mast solidly to the ocean, your mast will be at exactly the same electric potential as the ocean. Figure 3. Box 78 In an increasing number of marinas, there are substantial DC electric currents running through the water. Our first thought might be to simply make the ground connection to a metal thru-hull, propeller shaft or other underwater metal. The best example is your bronze propeller on a stainless shaft. With over 250 store locations, 100,000 products in stock, and knowledgeable Associates, trust West Marine for your boating, sailing, fishing, or paddling needs. I have a shaft tube and composite rudder bearing so all that was underwater was thru hulls and my stainless exhaust tip. Because of its close proximity to bilges, bonding system wiring lives a harsh existence. Really understanding how her electrical system can damage a boat’s metal components will help you to avoid costly replacements and repairs. If the ballast, engine, and lifelines are available, however, they generally make a high performance ground. Bonding System: The boats bondingsystem is basically a “Daisy Chain” of wires and cables. If you feel like spending real money on galvanic isolation, you might as well do it right and buy an isolation transformer. Do not bond any thru-hulls or other immersed metal that can be electrically isolated. But as we all know, wire connections can go bad. Table 2 from ABYC E-2 shows the recommended range of cathodic protection for boats with different hull materials in saltwater. Protected metals must reside in the same “body of water” as the anode. 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.". How many times have you been told (or thought), when evaluating a corrosion or electrical problem, “It’s the result of a bad ground”? Think of it as plating, but in reverse: electricity is being used to remove metal. 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 … 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. 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. If dissimilar metals corrode when connected, then why, you might ask, is it beneficial to connect them via a bonding system? His victories include the 2005–06 Volvo Ocean Race and 11 wins in the Pacific Transpac race. Boat bonding systems are a network of electrically connected metallic parts and components. One school of thought suggests that if you must use stainless steel underwater (e.g. It consists of the green grounding wire in the AC wiring system and serves the purpose of preventing shocks or electrocution. One square foot is recommended for use in salt water; fresh water requires much more. Note that this meets the ABYC recommendation. In the simplest of terms, bonding systems are an interconnection of underwater metallic components, including through hulls, struts, rudder stocks, and propeller shafts. Figure 2. It is good practice to include the HF/SSB radio itself in this network of ground tapes. See figure one. Terminals should be tin-plated and connections made using conductant paste. That’s the how, but why bond? Well, the EPA has us back to copper again, only this time cupric oxides are the toxic agent. I’m installing a bonding system on my boat. The bonding system is a system that serves multiple purposes in a typical scenario. There is one more important piece to the bonding system puzzle, the well-known but often misunderstood anode. Fasten the tape securely to an insulating piece of phenolic or to a terminal strip, cut a 1/10-inch gap across the tape, and solder several 0.15uF ceramic capacitors across the gap. Connect a 4 AWG battery cable from the base of your aluminum mast to the nearest keel bolt from external ballast. © 2021 Professional BoatBuilder Magazine. Electricity. Stray current corrosion can consume underwater metals like the propeller shown here in just a few days. The in-line ball valve used here lacks ABYC and UL compliance as a seacock. He is the technical editor of Professional BoatBuilder, and is writing a book on marine systems, to be published by McGraw-Hill/International Marine. By 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. Stories among marine electricians regarding the sorry state of bonding wires and terminals are legion. It shows the components of the circuit as streamlined forms, and the power … 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. Ground fault circuit interrupters (GFCI) should be installed in each AC circuit. Make sure that this is the case. We said to leave all bits of immersed metal electrically isolated when we described electrolytic corrosion and hot marinas, but then we said to connect wires and copper tape to your keel and engine for lightning and RF grounds. Think for a moment about this… Read more », Quirky marine toilets are a reliable source of wonder and potty humor during onboard cocktail banter, but they’re a lot less amusing if you’re the master, mate, or mechanic charged… Read more », Professional BoatBuilder is written and edited for boat builders, repairers, designers, and surveyors. I've had zincs last as long as 1 1/2 years before needing replacement. Generally, anodes should be replaced when 50% or more depleted. 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. When the anode is depleted to the point where it’s unable to maintain the aluminum at a voltage more negative than its freely corroding potential, the aluminum will begin to corrode in spite of the presence of an anode. 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. 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. Dynaplates) can be used as radio grounds in situations where the ballast or engine is unavailable or awkward to connect. The DC load returns of all branch circuits should be tied to the negative bus of the DC distribution panel. In turn, the negative bus of the DC distribution panel should be connected to the engine negative terminal or its bus. As outlined above, it is avoidable trouble. There is a very good reason for this confusion as the requirements surrounding bonding conflict. See Practical Sailor, August 15, 1995 for a detailed treatment of the green wire. The best protection is to put a zinc right on the shaft next to the propeller, or a zinc on the propeller nut. 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. In those cases, the shaft brush provides a link to the vessel’s bonding system and the anodes to which it is connected, the advantages of which will be explained below. 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. Certain Galvanic Isolators (e.g. See Figure 3. I thought from what I read online When I put the boat together that it was unneeded.. and since it was simpler I could just zinc the shaft and rudder and be done.. 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. 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. An internal bonding circuit connects the major metal objects on a boat to the grounding plate via bonding cables. In the old days, the technique of bonding everything together worked okay. The battery negative is also connected to the engine negative terminal or its bus. These DC currents in the water will cause electrolytic corrosion to your bonded thru-hulls or metal parts. Hose clamps and unterminated conductors are a poor means of making such connections. The boat's electrical system should be connected to seawater at one point only, via the engine negative terminal or its bus. While not absolute, bonding systems do provide some measure of protection. Never use the mast, engine, or other metal object as part of the return circuit. November 9, 2019 by Larry A. Wellborn Variety of boat bonding wiring diagram. Like any other critical component, bonding systems should be inspected regularly. Then, connect the grounding conductor (green) of the AC panel directly to the engine negative terminal or its bus. The commercial units look like a coax "barrel" connector. Of its close proximity to bilges, bonding systems live a harsh life, near often... Bonding system to work the well-known but often misunderstood anode or awkward to.! Editor of Professional BoatBuilder, and lifelines are available use up and down to... Returns of all branch circuits should be tin-plated and connections made using paste. 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