Saturday, April 15, 2017

SEACOKS HYSTERIA


As most of you know British magazines some years ago made a big fuss about brass seacocks on new boats (they still do) and hysteria about that was propagated like wild fire on boat forums.
https://trip.ayy.fi/wordpress/wp-content/uploads/2014/08/Seacocks.pdf

It seems that the main culprit is the RCD, the ruling body for the conditions needed for boat certification in Europe when they state that the seacocks used should be corrosion free for at least five years. From that to the idea that seacocks will only last 5 years was a quick jump and even worse, some just say that if a new boat does not come with bronze seacocks they should be immediately replaced, as if the boat was in eminent risk.

Brass regular seacock
That of course makes no sense. Almost all production boats come with low quality brass seacoks (CW617N) and the average time they need changing is about 10 years.

That does not mean that a seacock due to some unusual circumstances does not need replacement after only one year or two and because of that seacoks should be thoroughly inspected every year and changed at the smallest sign of corrosion, white powder or small changes in color.
Brass DZR seacock
The problem of brass seacocks has to do mainly with dezincification, a galvanic process that extracts zinc from the brass leaving it fragile. It can happen if the boat zincs are not in a perfect condition or if there are abnormal electric currents on the water. It will probably happen anyway after many years, but it can happen in just some years under abnormal conditions.

It is rare but there are some well known cases where seacocks lasted just one year or two. So does that hysteria about brass seacoks make sense? Well, the truth is that boat builders should be using a higher quality brass, more resistant to dezincification (DZR) and almost all of them are using a lower grade brass but the truth is also that even high quality bronze seacock manufacturers don’t warrant their products for 5 years and I know of some bronze seacocks (of low quality) that lasted only one year or two. All seacocks should be carefully inspected every year even if that does not mean that they all last the same time.

RCD has its share of guilt on this issue because while stating that the seacocks should be made of corrosion resistant material don’t specify the allowed materials and as almost all brass valves will be able to resist the required 5 years (on normal circumstances) boat manufacturers, to save some coins, don’t use proper long term corrosion resistant materials on seacocks. Hopefully there are some talks that it is going to change due to RCD new demands. A good article about the subject:
http://korrosion.dk/onewebmedia/Corrosion%20i%20Through%20Hull%20fittings%20and%20seacocks-070616.pdf

Should we be very carefully about seacocks and seacocks inspection? Absolutely! 

Should regular brass seacocks be changed after 10 years (no matter what) or changed at the first signal of discoloration, white powder or signs of corrosion? Absolutely! 

Blakes bronze seacock
Should we be worried when we buy a new boat with having seacock problems on the next few years? Nonsense!!! even if that does not dispense seacock inspection each year.

Should you be worried with seacocks when we buy a used boat with 10 years or more? Absolutely! As well as with rigging, rudder and many other parts that are more expensive than seacocks. That does not mean that we should not replace them, if the previous owner has not done that already. The problem here is that many still look at a 10 year old boat as if it was an almost new boat, including the engineer that wrote that article above about corrosion on seacocks.

Should you look at the seacock’ materials when you buy a new boat? Absolutely!... they are a good indicator of the boat building care with the choice of materials but I would not say that they should be more important than keel and boat structure, keel bolts, chainplates linkage, rudder assembly, bulkheads, hull material and building techniques. All are good indicators of boat quality but while seacocks can be easily replaced, all other mentioned parts are not.

Should you mount bronze seacocks when replacing brass ones? Not necessarily, DZR (that is also brass) performs better than some bronze ones and some plastic ones. High grade bronze seacocks like Blakes or high quality plastic ones like the True design may be a better option than DZR Brass but they are justifiable only if you leave the boat full year on the water.
http://www.holmedodsworth.com/materials/datasheets/brass-datasheets/cz132-cw602n-dzr-brass

True Design seacocks
Anyway the future seems to point to good quality plastics seacocks, that offer a lesser price than top quality bronze ones and are full corrosion proof. However they need to be of very good quality plastic to assure the needed strength.

Should boats have mandatorily better seacocks (RCD) than the ones that are installed now by almost all boat builders, made of regular brass quality? Absolutely! 

Is there a reason for the hysteria about the ones that are installed now? No, if you have the knowledge to deal with that, after all there are tens of thousands of boats around with less than 10 years on the water and they are not sinking due to defective seacoks, but there is reason to be concerned about seacocks and carefully inspect them every year and change them after 10 years (if made of regular brass) and I bet many don’t do that and that is one of the reasons for this post.
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This will be the last post in a long time. I have not been posting because I have been preparing my sailing season that will start in some days. I will come back only in October…so, till then, fair winds to all and have fun sailing.

6 comments:

  1. Paulo , I will miss your web presence , fair winds
    Jari

    ReplyDelete
    Replies
    1. Thanks mate! Fair winds to you too.

      Delete
  2. Have fun, see you in the winter again :)

    LeoV

    ReplyDelete
  3. Fair winds Paolo :)
    We will be waiting for your return. Take care and enjoy!

    ReplyDelete