Thru-hulls And Seacocks

[Lighthouse]

A great primer article on thru-hulls and seacocks - HERE.

This stuff is really important to keeping your boat afloat.

[redbopeep]

Originally Posted by Lighthouse

A great primer article on thru-hulls and seacocks - HERE.

This stuff is really important to keeping your boat afloat.

Yes! this a great resource about seacocks

[The Cruising Kitty]

Just went to a lecture at the Cruising Association on the brass seacock situation in the EU. I am scratching my head.. definitely in the amazingbuttrue category.

In the EU, the European Regulations for Small Craft have been rewritten (1998) to say that fittings must be corrosion resistant - for at least 5 years! This applies to fittings beneath the waterline. And guess what, it seems that many manufacturers in the EU have started building yachts 'to standard'.

Confusing the issue further for boat owners is that even if you know you want bronze (or DZR) fittings, there is no requirement for this to be clearly labelled (or labelled at all) on packaging. Even chandleries are often not able to correctly identify what the parts they are selling are made of (according to the speaker at the CA lecture I went to).

Does the same situation exist in the USA? If I buy my fittings in the US can I solve this problem? Are US boatbuilders using brass seacocks?

Any insight would be much appreciated. Thanks in advance.

[JeanneP]

Bargain boat manufacturers tend to use bargain parts. After some issues with various gear, Peter and I search for Made in the USA cast metal parts. Groco, Perko, and Apollo are all US manufacturers of brass plumbing fittings, but I doubt you'll find a builder's spec. sheet that goes into that much detail about the quality of its plumbing fittings. Having heard of no problems with quality, I would venture to say that if it's made in the U.S. and says "brass", I would accept that as fact.

More commonly, you'll find Marelon fittings installed to save money. Since they are also lighter in weight, one might investigate whether these are more commonly found on multihulls. Most experienced sailors avoid Marelon due to their high (relatively speaking) failure rate. We have long memories when it comes to gear failure. But when looking at boats to buy, that is a "kicking the tires" and survey situation.

Not very helpful, am I? Sorry.

[redbopeep]

It is my understanding that the reputable brands (including the three JeanneP lists) all make BRONZE not brass thruhulls and seacocks. Though a high quality brass may pass marine testing just as a bronze does. Bronze uses Tin whereas Brass employs Zinc in the alloy. Some brasses actually do quite well in salt water (see Naval Brass for example) but still, bronze thruhulls are likely best. In the US, you will find items which have passed appropriate testing for use on boats to be labeled "Marine UL Listed" or with the UL spec (e.g. UL-1121).

Reputable mfrs of seacocks and thruhulls include:

Apollo,

Blakes,

Groko,

Perko,

Willcox

I hope this information is helpful. You can find numerous retail suppliers who carry these thruhulls and seacocks.

I dare say that someone might use brass (not bronze) thru hulls for a very long time without failure due to de-zincification as long as the boat has a properly sized, placed, and maintained sacrificial anode. Even bronze seacocks will "pink" from electrical activity if the boat's anodes (typically zinc but sometimes mild steel or another material) are not properly sized, placed or kept in proper shape. In seawater, if the anode is not experiencing at least 400 millivolts (tested with a silver-silver chloride half cell and V-Ohm meter) it will not be doing its job and that means other metals on the boat will be sacrificed. That means brasses will lose their zinc and bronzes will lose their tin. Both leave behind a copper structure which is "pink" and not as strong as the original bronze or brass alloy.

Our boat is wood so we have to be very careful to assure that the we have just the right size of anode and maintain it. We use a zinc on the prop shaft but on the hull/keel/rudder interface, we use mild steel as, on our boat, zinc anodes are too aggressive and the wood adjacent to the anode could be damaged. So, we maintain between 500 and 630 millivolts. If we go over 800 millivolts or under 400 millivolts we risk damage to the wood and bronze/brasses respectively. We replace the zinc on the prop shaft every 8 months or so, the mild steel anodes are replaced every 4 months or so to maintain the proper voltage potential. Fiberglass boat owners don't have the same concern on hull material degradation and typically can go with a larger anode and longer between service.

Fair winds,

[The Cruising Kitty]

Thanks both Jeanne P and redbopeep. These answers are about as comprehensive as it gets!

Looks like I will be heading to the US to pick up/replace my fittings. Good to know.

[JeanneP]

Thanks, Brenda, for catching my mistake. Bronze is what I meant to write, "Brass" is what I was thinking about warning against. Or, as a friend said many years ago, the fingers typing are faster than the brain thinking.

We had a brass fitting on the sailboat, and once when we hauled the boat, one of us accidentally hit the fitting and it shattered just like glass. The comments we heard were that the zinc in the brass acted the same as the sacrificial zincs we had on prop shaft and keel - sacrificed and leached out of the metal.

[jackmox]

Hi from jack mox so has anybody had any experience with sterling gen sets ie external combustion gensets i cant find any real info but need quiet power so one of these may be the way forward ( maybe

[Brent Swain]

With steel hulls, welding in type 316 stainless sch 40 pipe nipples, with stainless ball valves on them, has given me zero problems in over 40 years.