Boat Through-hull Fittings Industry Market Research Report

Boat Through-hull Fittings Industry Market Research Report.Seacock information that every boat owner needs to know


Many of yachts, along with the new ones, are in jeopardy of sinking, due to through-hull fittings made from insufficient proper materials.                      

We have found that lot European marine equipment stores are selling out brass and Inox ball-valve-type seacocks which are created for fresh water plumbing and piping systems.

In salt water, brass can incline to a form of corrosion called dezincification, which makes them brittle and subject to failing.

We have checked yachts where cheaper brass seacocks have corroded so severely that they snapped off in the hands-on inspection.

Typical brass will probably last five years, and EU law permits that.

But if you introduce other factors, like electrical current leakage and associated electrolytic action (especially with marina shore power), the rate of dezincification of brass fittings will quickly speed up.


Inox seacocks have the Same issue. A lot people conclude on “first look,” because Inox in not corrosive that Inox is a proper solution for seacocks. But Inox is delicate on electrical current leakage and associated electrolytic action in sea water, and if it has been susceptible to these electrolytic environments, it quickly breaks.

Lot boatbuilders use cheaper brass fittings. However, our research fins that they are easy to fail, with potentially disastrous results. In recent years, we found that some of the world’s leading boatbuilders have been using standard brass fittings below the waterline. These typically reside of 40% zinc and are patently not convenient for use below the waterline. Equally regarding, many yachtsmen, due to a shortfall of advice or proper labeling in marine stores are buying substitute seacocks made of brass assuming they are buying bronze or DZR (dezincification resistant brass).


What’s unsound with typical brass?          

In salt water, brass – a mixture of copper and zinc – is inclined to a form of erosion called dezincification. Zinc drained from the metal, and the extra copper shell becomes porous and frail. The consequence is often referred to as the metal becoming ‘carroty,’ due to its color. In the former times, boat builders who used brass fittings were often exposed out and had to adjust their terms. But it all changed in 1998 when the European Community’s Recreational Craft Directive (RCD) grew into force. Where seacocks are troubled, it has made circumstances worse.


All boats require now adapt to a wide array of mandatory ISO standards. The rules for metallic seacocks and through-hull fittings (IS0 9093-1) states:

‘Materials used shall be corrosion-resistant…’


But surprisingly, the directive defines corrosion-resistant as: ‘a substance which, within a setting time of five years, does not show any glitch that will damage tightness, intensity or function.’



Five-year lifespan – or less!

Is a service of five years life adequate for necessary below-the-waterline fittings? If I were buying a yacht, whether new or second-hand, I would be very awkward that such an essential joint could fail and sink the boat after just five years.

Is all the more unsatisfactory because we could be using other materials that are proven to have a life far more than five years?             

In 1980, a British Standards specification was issued for a new type of brass, selected CZ132, which was immune to dezincification. Is now known as DZR (dezincification resistant) brass and has the EN classification of CW602N. This material is determined to be the match of bronze in a saltwater environment and is now in regular use.

Regrettably, the other connection it has with bronze is the price.

In the lack of any special conditions, such as current leakage and associated electrolytic action, regular brass will probably endure the prescribed five years. Brass is about a quarter the price of bronze or DZR, so the choice to use it is being motivated by cost.

Buyers risk a lottery. The circumstances are even more challenging for yacht owners, and yards are replacing fittings as part of good, safeguard preservation. The ball valve has become by considerably the most well-known type of seacock used and quickly the problem is multiplied, contrasted to conventional seacocks because there are three elements in the construction: the valve, the through-hull fitting, and the tailpipe to take the hose.

These ingredients may have rooted from different suppliers, and there is no mandatory requirement to mark them. Buying these can be a whole lottery.

We have found that customers can face a lottery, same by offline and online marine stores.

It’s vital they get good advice.  

Because of brass, DZR, and bronze are essentially same in the image; it’s not unexpected that there is trouble.

Where these pieces have bundled, there is an inclination to precisely mark DZR and bronze items, but not to label brass at all, with potentially harmful consequences. We recently bought two tailpipes, as would be used on a standard heads discharge assembly, in a large, well-known chandler’s store. They shrink-wrapped into backing cards, and the bronze one was named, but the brass one was not labeled at all. Both were indistinguishable in appearance and show, apart from one little word – if it doesn’t say ‘bronze’ or ‘DZR,’ you must think that it isn’t.


‘Tonval’ spells danger

Brass also bartered under the name Tonal. A few minutes seeking the Internet will reveal mail-order handlers explaining this conventional 60/40 brass as bronze. Is remarkable because suggestions were made to the industry as long ago as 2000 about this very subject in a Marine Accident Examination Branch (MAIB) report on the flooding of a fishing boat, Random Harvest, due to the negligence of Tonal brass fittings below the waterline.

The article should be essential reading for all yacht owners. It is one of the greatest texts we have read regarding galvanic and electrolytic corrosion. It notes rates of corrosion for everyday brass in seawater and, as a result, decides that regular administration would not meet the RCD’s five-year requirement contained in ISO 9093-1.


Real-life story from one of European marine stores during our research

We are visit local European marine stores during our research personally too.


Conversation with seller in marine store is below:

Our volunteer researcher: Have this valve any kind of certificate?

Marine store salesman: Yes, we have certificate.

Our volunteer researcher: Can you show me that certificate?

Marine store salesman: Yes, I am go find and show you certificate. You are first one who ask us this J

Our volunteer researcher: J

Marine store salesman: Here is certificate, you can see….

Our volunteer researcher: But this is certificate for wine barrels! I will use valve in marine conditions. Good, this valve is not fully ordinary valve, but this is far from marine conditions valve.

Marine store salesman: Most of all local stores use similar ones, we must have maintenance low prices. These valves we have in store actually only. If you wish better marine valve, pls specify what you are looking for and we’ll see can we order valve type you want.


This small real-life story tells you all on own way.


How to distinguish genuine from corrupt

Purchasing the proper skin fittings and tailpipes is essential, but what of the valves themselves? The ball valve with number CW617N brass plug but it’s not all it may appear.


The branding ‘CW617N’ is the European designation for regular brass with a high zinc content. Ball valves are made in their millions using this substance because they work so well in fresh water. Brass valve expelled from packaging and turned over to show labeling plumbing and piping systems, but the material is not marked as dezincification-resistant and should not utilize in salt water.

To be honest, this ball valve has solid walls and may well satisfy several years if immersed in seawater. But wisdom suggests that if any electrolytic action is present – and with the propagation of shore power supply, plus great onboard electrical systems, this is common then the rate of dezincification is swiftly quickened. Many boat owners believe the ball plugs and associated parts in their boats to construct of DZR or bronze, but, in truth, some are conventional brass alloys – commonly containing 40% zinc. The Copper Development Organization has fixed up a UK plan to mark genuine DZR plugs with the designation ‘CR, ‘ but this is not required by law.

Inadequate labeling Several suppliers’ websites and packaging are precise in their depiction of materials, but some are not. If you are supplanting any of these vital below-the-waterline elements, make sure you are receiving the right ones. With such demand on costs, the attraction to use tricky parts, which look same, is high. With underwater through-hull fittings, any opportunity should dodge. Bronze or DZR should be the exclusive choices for all metallic seacocks and associated ingredients.

We wrote many significant boat builders, asking how they could excuse installing standard CW617N brass fittings in new vessels. We experienced no response from the yacht builders, but a one major motorboat builder suggested the reason that they will last the five years prescribed in the RCD’s ISO 9093-1 standard. But if you found other factors, such as electrolytic action, which quickens the rate of dezincification, the dilute of brass fittings may be very speedy indeed.

The dezincification of brass mixtures in salt water is appropriate and understood for incredible 90 years. Why in this enlightened age of advanced great-production boatbuilding are we using a secondary material for such essential fittings below the waterline? If boat builders persist in fitting second brass ball valves and associated elements, they should at least make the facts apparent to their consumers, who would then understand the significance of a regular inspection regime to evade potential disaster. The ISO standard defined as ‘under review,’ so now may be the greatest chance for it to repaired. In the meantime, all yacht owners before buying need alone ask evidence of the elements used in their seacocks from every marine store.



Seacock Grounding – To bond or not to bond


Googling the topic seems to find plenty of internet sites giving advice that ‘through-hulls’ should be bonded. Our research in local European marinas find that few maintenance workers suggest to bond seacocks too.


Our own research finds that they are better left unbonded, as sometimes unexpected effects can result.



Inox seacock grounding:


Brass and bronze seacock grounding: SOON MORE..




Other options: Plastic seacocks

Plastic seacocks are the choice of many long distance cruisers.


The Marelon range, made by Forespar, are glass reinforced DuPont Zytel.



– Each assembly is sold as a unit. Fittings made of the same material to cover every installation

– No galvanic or electrolytic corrosion – a big advantage

– Minimal maintenance

– High-quality, dedicated marine products



– Not as fire-resistant as metal, thus not ideal for use in engine spaces and other areas with a fire risk.

– Not ideal to use near engine because long-term high vibration issues.

– More expensive than mass-produced, nonmarine brass seacocks.



What to avoid?

CW617N brass valve and and other product without marking that’s is enough good for seawater conditions.

What you are looking for?

DZR brass ball valve with ‘CR’ (corrosion-resistant) marking.

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