For boat owners around the globe, Deep Blue Yacht Supply is your trusted source for the best zinc anodes in the marine industry. We are committed to providing the best zinc anodes, at the lowest prices, with superior customer service.

Zimar Zinc Anodes set the standard when it comes to cathodic protection. Zimar Zinc Anodes meet all standards set forth by Mil-Spec A-18001K, Mil-Spec A-18001A, and Mil-Spec A-18001. Zimar Zincs are individually hand poured to assure the highest possible zinc concentration and lowest amount of porosity.

Trust Deep Blue Yacht Supply to help equip your boat with the best possible zinc anodes. Deep Blue Yacht Supply is able to provide the ultimate sales and service experience, when it comes to selecting the best zinc anodes to protect your investment against corrosion. Deep Blue Yacht Supply has a huge inventory of the best Shaft Zincs, Plate Zincs, Rudder Zincs, Nut Zincs, etc.

Seawater is inherently corrosive and this is even more pronounced in the case of components that are made of two different metals. Any time two metals are in contact in seawater they will form a battery and one of the two metals will give up its electrons to create the current that flows between the two metals. This process is known as galvanic corrosion and unless you want your boat to begin failing you it is important that we halt this process before it begins. This is done by using a third metal which will more readily give up electrons to create a current. In boating, zinc is most commonly used and the zinc pieces are called zinc anodes, or more commonly just zincs.

Zinc anodes are used on boats anywhere two metals come in contact with each other and are thus subject to galvanic corrosion. This is most common with a stainless steel shaft and aluminum propeller, but there are many other places where two different metals come in contact on a boat. Without the protection of a zinc anode you risk corrosion seriously affecting your parts and components.

Some people think that as long as zinc is present it will protect the other metals on their boats, however they soon learn to their chagrin that this is not true. You can not protect your metal components by simply hanging a piece of zinc over the side of the boat, the zinc anodes must be in contact with the metals they are protecting. This isn't a big deal though as boat and engine manufactures have designed parts to allow for the inclusion of zinc anodes, from the zinc collar that goes around your shaft to the zinc hull plates that are used to protect bronze through-hull fittings to the various zincs in an engine there is typically a protection wherever there are two metals with the possibility of galvanic corrosion occurring.

Now that you know about the importance of zinc anodes it should also be stressed that these anodes do not last forever. Because they are sacrificing themselves to protect your more important metal parts they corrode themselves and are slowly worn down. As a rule of thumb the zinc anodes should be roughly 1% of the surface area they are protecting and should only need to be replaced annually. To be safe though you should inspect all your metal parts regularly for signs of corrosion and if any is present replace your zincs immediately. Typically zincs are replaced when they are only half consumed. Once they go beyond this they are significantly less effective and you risk damage to the parts you are trying to protect.

The good news is that zinc anodes are not expensive, many cost just several dollars and even larger hull plates can be had for under $30 in many cases. When installing zinc anodes be sure that they are in contact with the metal being protected, do not paint the surface of the zinc and make sure that both the zinc and other metal surface are bare and bright before installing the anode. In the case of your engine you should refer to the owner’s manual to be sure you know the location of all the zincs, some can be difficult to locate if you aren't aware that they are there.

It is good that there is a way to protect your metal parts, but the protection only lasts as long as you keep your zinc anodes bigger than half depleted. Make it a habit to check for corrosion regularly and replace those zincs when they are half depleted.

The history of Cathodic Protection

Way back in 1824, a certain Sir Humphrey Davy in the UK, noticed that the copper sheeting on warships was decaying rapidly, and made it his business to try to do something to prevent this from happening, to lengthen the life of His Majesty’s ships of war. He realized that it was due to the constant contact with seawater, which was causing the copper to corrode and, while conducting an experimental investigation, discovered that iron anodes helped tremendously, to protect the copper, and cathodic protection was born.

However, one of the side effects of this process was increased marine growth on the ships, which had an adverse affect on their performance. After some deliberation, the Royal Navy decided that it was better to allow the copper to corrode as it normally did, than have to deal with the extra marine growth on their ships, so Davy’s discovery was not used any further.

Davy carried on with his experiment, assisted by a pupil of his, Michael Faraday, who continued with these experiments after Davy’s death. Faraday discovered a connection between corrosion and electric current in 1834, which actually formed the basis of cathodic protection as we know it today.

Even Thomas Edison experimented on ships in 1890, but, because of the lack anode material and suitable current source, was not successful. It was only in 1928 that the United States started making use of cathodic protection on oil pipelines – more than one hundred years after Davy’s experiments.

Cathodic protection basically, is the technique of making a metal surface the cathode of an electrochemical cell, in order to protect that metal surface from corrosion. The simplest way to apply it, is to connect the metal that needs protecting, to another metal that is more easily corroded, a sacrificial metal in other words, making it perform as the anode of an electrochemical cell.

Sacrificial anodes are manufactured in various sizes and shapes, using alloys of zinc, aluminum and magnesium. Zinc anodes have high driving voltage, and are suitable protection for marine structures and pipelines against corrosion caused by seawater. Zinc alloy anodes can also be used in areas where sparking is a risk and needs to be avoided, such as in tanks where flammable hazards are stored.

Cathodic protection is commonly used in steel fuel or water pipelines, storage tanks, steel piers and jetties, offshore oil platforms, onshore oil well casings, as well as the metal reinforcement bars which are used the majority of the time, in concrete structures and buildings. Cathodic protection also used in some cases, to prevent stress corrosion cracking as well.  Deep Blue Yacht Supply offers some of the best boat zincs (Zimar Zincs) in the industry, as each is hand poured and contains the highest amount of zinc.

Understanding Zinc Anodes

Most boaters know about the importance of zinc anodes.  Zincs, as they are called, protect the metals of a boat from galvanic corrosion. However, many boat owners are somewhat unaware that steps must be taken to make sure that their zincs actually work towards their intended purpose. If you want to make use of sacrificial zincs on your boat, you must make sure that the zincs are actually connected to the relevant metals and that the zincs are uncovered and able to be exposed to the sea water. Doing so is the only way that these items will provide the necessary protection.

Your first step towards making sure that your zinc anodes are in working order is to make sure that they are actually in contact with the metal that needs to be protected. There are some individuals that think that, somehow, the zinc will act as a magnet for the corrosive elements of the sea water. In truth, though, the zinc must be in some kind of contact with the metal it is meant to protect. This means that you must either make sure that the zinc is making direct contact, or is somehow wired to the appropriate metal area. If this is done, the zinc anodes will properly work in a sacrificial manner.

You must also make sure that the zinc anodes are properly exposed for them to work. The entire purpose of the zinc in the zinc anodes is to be sacrificed, and covering up the metal can make the process work poorly, or not at all. As such, you must never paint the zincs on your boat. It is does not matter if you consider the metal to be an eyesore or if you want to maintain a uniformity of color – if the zincs are in any way covered, they will be smothered and thus rendered worthless.

If you want to make sure that your zinc anodes function correctly, it is important to take the time to really understand how they work. Once you do, you will realized that they must be both exposed to the sea water and in contact with the metals that they are meant to protect. This may mean a bit of extra work for you as a boat owner, but it will save you quite a bit on repair costs down the road. After all, the work put into these zincs will save you from more work on more important parts.

Where to place your zinc anodes

Zinc anodes are quite important for most ocean-going boaters. While they are relatively simple items, they can make a huge difference when it comes to the wear and tear of metal parts. If you are a new boater, you may wonder about where to place these anodes. There are several important areas, but none are more important than the hull, the rudder and the propeller. These areas are particularly prone to galvanic corrosion, and thus must be protected at all costs. As a boat owner, it is up to you to make sure the anodes are in place and working.

First and foremost, make sure that you have zinc anodes properly placed on the hull of your boat. If you have a boat with a metal body, the reason for this should be obvious – you do not, after all, want to lose your hull to corrosion. If the body is not metal, you should still take the time to make sure that zinc anodes are attached to any kind of bonding circuit. If you fail to do so, you may find that any sort of metal fitting that is underwater and electrically bonded will be damaged over a relatively short period of time.

It is also important to make sure that your rudder and propeller are likewise protected. Most propellers feature some kind of zinc anodes, but it is important to make sure that they are replaced when necessary. These usually clamp around the propeller’s shaft, and taking a moment to make sure the area is clean before installation is vital. The zinc anodes attached to the rudder are usually in the form of discs, and can be bolted directly to the surface of the rudder. They are generally designed to make sure that the boat does not lose efficiency due to their presence.

If you own a boat, it is always wise to do what you can to protect your investments. Boat zincs are incredibly important, and making sure that your vital areas are protected properly is always a good idea. Make sure that you change your zinc anodes when necessary, as corrosion can still occur when the anodes finally lose their metal to the ocean. It generally takes some time to occur, but it is often a good idea to make sure that you check on your anodes when you do any kind of basic boat maintenance or before you take it out on the water for an extended period of time.

The Need for Zinc Anodes

Boat zincs are an important part of a marine craft propulsion system because they keep other metals from corroding and deteriorating in the water.  What is not thoroughly understood by some boaters, however, is the fact that zinc anodes cannot do this vital function unless they are left in their original state.

This means that boating enthusiasts need to keep the boat zinc free of paint.  A surface layer of paint will smother the zinc’s ability to sacrifice electrons so that the other metals nearby need not do so.  This sacrifice of electrons leads to eventual corrosion.  Therefore, boaters should keep their boat zincs in original condition, watching them closely so that they can be replaced when they have worn away and a new zinc anode becomes necessary.

Not just for propulsion

Boat zincs are useful for protecting other metals.  When it comes to boats, this means that their usefulness extends far beyond the propeller area.  To be sure, propellers are typically guarded against corrosion by the presence of a zinc collar around the shaft, but metal rudders are also at risk of corrosion.  The typical boat zinc in this situation is a disk that is bolted onto a metal portion of the propeller.  Lest the addition of boat zinc create turbulence or drag, zinc anodes for use on rudders usually have a shallow shape that is slightly domed.  This helps them to present a streamlined profile when attached to a rudder so that boat performance can remain high.

Understanding Cathodic Protection

Most metals are subject to corrosion, and their tendency to decay in the presence of water and oxygen is only exacerbated by the presence of seawater, which contains a number of dissolved solids including salt.  There are ways, however, to retard and even control the process of corrosion.  One of the chief methods is known as cathodic protection.

In this technique, the metal to be protected is paired with another metal known as the “sacrificial metal.”  The two need to be connected in a way that will establish them as an electrochemical cell.  Once this is done, the sacrificial metal will decay rather than the protected metal.  This is accomplished by making sure that the sacrificial metal is, in fact, more prone to corrosion than the other metal.

With cathodic protection in place, the sacrificial metal will steadily corrode until it is completely gone.  During this process, the other metal will not corrode.  However, as the sacrificial metal reaches the end of its useful life, it will need to be replaced in order for its protective function to continue.

Uses for Cathodic Protection

This technique is often used in marine applications.  For example, piers piles made of steel as well as offshore drilling platforms may use sacrificial metals to protect the integrity of the structure.  Ship hulls and propeller/engine combinations may also use cathodic protection.  In order to avoid creating a “dragging” force that will interfere with speed or navigation, sacrificial metals are often shaped in special ways that allow them to integrate well with boat design.

About Zinc Anodes

Without a doubt, some parts of a watercraft are much better known than others are.  While even non-boaters have probably heard of propellers, outboard motors, and rudders, some boating enthusiasts may not have heard of zinc anodes, also known as boat zincs.

What are Boat Zincs?

Boat zincs come in a variety of shapes such as plates, disks, and cylinders, but what they all have in common is a surface area that allows the metal of zinc to help prevent galvanic corrosion on other parts of your boat. Zinc anodes work by giving up their own electrons so that other metals located nearby will not give up theirs.  Boat zincs in this way can help to prevent corrosion of boat parts such as stern drives, steel shafts, rudders, fittings, and above all, propellers themselves.

Boat zincs such as plate zincs, nut zincs, and shaft zincs are also called “sacrificial anodes” or “sacrificial zincs” because they will corrode as they keep other metals from doing the same.  Boating enthusiasts need to keep careful track of their zincs because once they have decayed a great deal, they will no longer be able to prevent corrosion effectively.  At this point, boat zincs need to be replaced so that propellers and other metal pieces have continued protection.

Boaters should also be diligent to check for corrosion on their propellers because such corrosion can mean that more zinc surface area is needed to protect it fully.  As a general rule of thumb, boaters need to have 1/100^th as much zinc surface area as the area being protected, but some situations will require additional zinc anodes.

Zinc Anodes Protects Metals from Corrosion

One unfortunate side effect of immersing metals in seawater is corrosion. A specific type of decay known as galvanic corrosion can happen when two kinds of metal are connected and then exposed to salt water.  In layman’s terms, this causes the metals to behave in a battery-like fashion; current will begin to flow between them as electrons from the atoms of one of the metals are converted into metal ions and lost into the seawater.  Galvanic corrosion usually proceeds at a rapid pace and destroys the metals involved.

This is obviously a large problem for boaters.  Propellers are frequently mounted on shafts made of stainless steel, but those same propellers are themselves made of other metals such as aluminum or alloys such as bronze.

Avoiding Galvanic Corrosion: The Role of Anodes

In order to avoid forming a battery circuit, designers of boats and motors have long used the technique of the anode.  This involves providing a third type of metal such as zinc, which is placed in electrical contact with the other two metals involved.  Designed to be “sacrificed,” this third metal has inherent qualities that cause it to readily lose electrons.  Since nature takes the path of least resistance, the zinc anodes will decay and eventually be replaced so that shafts and propellers can remain pristine.

Boat zincs can also help to protect other watercraft elements such as rudders and hull plates.  These zincs take a variety of forms including round plates, rectangular plates, and cylinders designed to encircle a propeller shaft.