Beneteau Responds to Seacock Query


Beneteau wrote a detailed response to our recent query from a reader regarding seacocks in his Beneteau (Seacock, Through-hull Caution Mailport, PS July 2017). We are continuing to look at seacocks and seacock materials. The last Practical Sailor in-depth report on seacocks was in 1994, so this is long overdue. If you have a relevant seacock story to share, send it to the editor at

Here is Beneteaus statement.

As they are distributed throughout the world, all Beneteaus are built to the stringent standards of CE certification. CE is the most widely recognized official global standard, and one that is mandated as legally necessary by dozens of countries. The CE directives and legal requirements are used as the reference for the materials and systems needed in order to build Beneteaus.

CE carries the weight of law in many jurisdictions, and Beneteau observes these; along with the legal requirements of governing bodies such as the US Coast Guard for the North American markets.

For well over a decade, Beneteau has been installing through-hulls and valves made of a duplex brass alloy which is approved for use in seawater, and which are sourced through a respected supplier.

Prompted by interest from a BoatUS member, Beneteau recently sent samples of the through-hulls and valves to be tested to confirm that they exceed the specific CE requirements of ISO 6957, the rule governing such items for corrosion issues. The testing was performed by the independent scientific laboratory of CETIM, and the positive results prove the examples met the ISO standard.

As with many materials submerged in seawater, over years brass alloys may deteriorate due to chemical or electrical reaction (electrolysis), sometimes at an advanced rate due to external forces. Electrolysis may also be caused by stray current coming from the boats electrical system or from shore side sources (such as docks or surrounding boats).

Electrolysis may also be the product of dissimilar materials in the water that create an electrical current that results in corrosion (batteries, metal bulkheads, etc).

To our knowledge based upon over a hundred thousand boats produced, serious corrosion on through-hulls is episodic, and in our experience the incidence of failure is very, very rare. And those limited episodes can normally be traced to some key contributor; such as stray current, improper wiring, failure to inspect on an annual basis, lack of maintenance, etc.

Beneteau confirms that it is mandatory to have a competent professional perform a thorough annual inspection of all underwater appendages, items and surfaces for function, integrity or performance, and that includes through- hulls and valves. The inspection of the through-hulls should be undertaken from both the inside and the outside of the hull looking for any color change.

We also require that there must be regular replacement of the protective zincs anodes (or magnesium if in fresh water). In the case of rapid deterioration of anodes, the cause of such activity must be investigated and a fix for stray current or the exceptional presence of dissimilar metals must be addressed. In some extreme cases it is not uncommon to have anodes erode within a matter of a few weeks. Those examples require extra anode protection or more serious remedies, and expert professionals should be consulted in such instances.

“In some cases it may be necessary to replace through-hulls after years of use, which in those occurrences are considered by Beneteau to be normal maintenance. There are also examples of through-hulls which, due to standing condensation or a leaking connection, visually appear to be severely degraded on the surface, only to find that after a short minute or so of polishing they are fully structurally sound, functional, and visibly improved. With proper maintenance and vigilance, through-hulls and valves will remain reliable and secure.

“As a general reminder, it is recommended that boaters close all through-hulls upon leaving any unattended vessel.”

Wayne Burdick

President, Beneteau Inc.

Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida.


  1. I just received a call from the boat yard that hauled my 2015 Beneteau Oceanis 38 informing me that 2 of the 3 referenced seacocks need to be replaced. this is a 7 year old boat, I have never had to replace seacocks that were less than 20 to 25 years old. After some research this issue does not seem to be as rare as Beneteau claims. As other owners have stated, they love their boats but Beneteau needs to look at this issue more closely and take responsibility.

  2. The author needs to research “electrolysis” more thoroughly.
    Electrolysis does not, cannot occur on boats. One is dealing with either galvanic or stray current corrosion.


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