General Info: When to replace thru hulls??

[LaBomba]

Originally Posted by downunder

Thru hulls and ball valves, not sea cocks on a Lagoon 400.

I would be looking at the link below at Compass Marine and consider installing flanged seacocks.

Replacing Thru-Hulls and Seacocks Photo Gallery by Compass Marine at pbase.com

And regardless of what you install or are already installed, keep some tapered wooden plugs on board "Just in case Murphy drops in".

[Lagoon4us]

Next will be Titanium 'Nylex' hose.........Give me a break

The hose is the weakest link, two SS hose clamps at 180 opposed is fine.

We are replacing our factory fitted 'brass' / 'bronze' ball valves after 5 years service. There's a lot of scaremongering on Forums but our personal experience is the factory fitted valves are still working quite nicely, but 5 years is enough.

Beware also what has been fitted by so called 'experts' to accommodate air-con, de-sal feeds etc because quite often they'll fit any valve and skin fitting that they can buy at a hardware store.

Unless you have traceability it's only an opinion as to whether a 'crumbly' brass valve was indeed factory fitted.

With all the negative talk i still have not seen, nor heard, nor found on the WWW one instance of a Lagoon being lost to these rascally so called 'brass' valves.

Sand a section of your skin fitting and compare it's true colour to this chart, i think they will not be yellow brass...

Copper Alloy Forms

[boatpoker]

Originally Posted by Lagoon4us

We are replacing our factory fitted 'brass' / 'bronze' ball valves after 5 years service. There's a lot of scaremongering on Forums but our personal experience is the factory fitted valves are still working quite nicely, but 5 years is enough.


Unless you have traceability it's only an opinion as to whether a 'crumbly' brass valve was indeed factory fitted.


Sand a section of your skin fitting and compare it's true colour to this chart, i think they will not be yellow brass...

1. Replacing them after five years is a good idea since the CE standards only require them to last five years. Real bronze seacocks have been lasting 40years plus and are still good.

2. That colour chart looks realy nice on a computer screeen but the differences in situ make it of little use.

3. Three of the Lagoons I surveyed were new boats still in possession of the dealer and all had brass throughulls and chrome plated brass ball valves. None of the fittings were marked with DZR or CR to indicate corrosion or dezincification resistance, in otherwords brass.

None of the above are major issues in fresh water unless electrolytic activity is involved but in salt water five years is about all you'll get and much less if galvanic of stray current is involved.

There is another thread on this forum that reprints an email from Beneteau (Lagoon) confirming that they use Brass. (Finally got the specifications of sea cocks from Beneteau. Unbeliveble)
Paul Stevens (linked in earlier post) in his articles also has communications from Beneteau (Lagoon) confirming they use brass.

[Emmalina]

Having just removed 14 thru hull fitting I can honestly say i was very impressed with the quality of these fittings. They are all 30 years old and there is no corrosion on any of them. I just opted for a sea chest / Manifold as there were too many holes below the water line. I have a large bucket full of the old fittings LOL

[Lagoon4us]

There are 3 to 4 metal skin fittings/ball valves on a base model Lagoon cat depending on how many toilets are fitted.

There are a further 2 metal ball valves that have contact with seawater that do not have skin fittings.

The sewage holding tank valves are plastic units and can number from 2 to 4.

The colour chart is an industry standard chart for visual recognition of metals.

I believe they only fit what will get them through their certification, personally it's abhorrent.

Interesting however the valves/skin fittings that i've looked at on some 20+ Lagoons were all in good working order and the age/model dates ranged from 2004 to brand spankers!

Cheers.

[barnakiel]

Start with visual inspection. If they look pristine, they are likely to be fine.

If they look iffy: take the worst case out and bang it some. See what happens and act accordingly.

b.

[Lagoon4us]

Originally Posted by barnakiel

Start with visual inspection. If they look pristine, they are likely to be fine.

If they look iffy: take the worst case out and bang it some. See what happens and act accordingly.

b.

But only when slipped, a de-zinced valve look's quite perfect till hit etc.....

[timbenner]

Thanks everyone! This has been very informative and given me confidence regarding what to use and how to do it. My conclusion, use the Groco Bronze flanged seacocks, with epoxy backing plates: Seacock Backing Plates / Alternate Method / No Through Bolts Photo Gallery by Compass Marine at pbase.com

Anyone know where to buy the G-10 epoxy/fiberglass sheet??

Next thread: "Advice/Experience Replacing Metric thru hulls and ballcocks, with existing metric pipe, to new Imperial thru hulls and seacocks?? Imperial/metric mish/mash"

[careka]

Originally Posted by offline

I believe that common practice on any boat is to lubricate anything that needs maintenance with large quantities of whatever cash is on hand.

like this

[sailorboy1]

Originally Posted by careka

like this

pictures worth a 1000 words, and in this case the guy probably used too small of a bucket

[Dockhead]

Originally Posted by timbenner

They claim that Titanium is 40% stronger and 40% lighter than Stainless Steel. I gave you the wrong link to titanium thru hulls. Here's the correct one: Thru-Hulls - Titanium

My God - I'm in love. Again . I'm replacing all my through hulls. . .

[Lagoon4us]

And a carbon fibre dunny!!!!

[Watercolor]

I believe you can get G-10 fiberglass sheets from McMaster Carr. www.mcmastercarr.com

[geoleo]

Originally Posted by osirissail

Well, first things first - the "Through hull" is the screw-in fittings that passes through the hull and into the "seacock." Which is the valve that allows you to keep the ocean on the outside of the hull.

Then there is the matter of whether your "Seacock/Through-hull" combination are made of metal (e.g. bronze) or resin (e.g., Marelon - or God forbid PVC).

Typically, bronze or actually any Seacock material gets "sticky" and unless lubricated and exercised become very difficult to open and close. So a schedule of lubrication and exercise (opening and closing) them is important. If they have never or rarely ever been lubricated or exercised then they might become "frozen" and you cannot open/close them without risking breaking them. In that case, replacing them would be advisable. Or at least removing or disassembling them to clean and refurbish makes sense.

Otherwise, if they are functional and not broken, cracked or otherwise compromised there would be no reason to replace them. However, if the Seacock/Through-hull is bronze it is possible that it has been subject to stray electrical currents and "de-zincified" which turns the normal bronze colored metal "pink." Then it would also be advisable to change them and correct the stray electrical problems.

Just like screws, Through-hulls come in different head styles - mushroom/round head or flush/flat head. Sometimes if the boat has been run down some hard dock or other obstructions the mushroom/round head style Through-hull can get the portion that is on the outside surface of the hull, scrapped off or broken. Then again it would be advisable to install new ones.

Also if the Seacock is not a tabbed base "flanged" style which is bolted to the hull and instead is merely being held in place by the threads of the Through-hull, it would be advisable to remove the Through-hull and check it for cracks in the threaded section. However, since the Through-hull portion is normally "bedded" with adhesive caulk is it rarely possible to remove it without breaking or destroying the fitting. So if there is no indication of any leakage leaving the system alone also makes sense.

So there are several variables to consider as to whether "replacing" them is advisable or not. More important sometimes is to check the hoses attached to the Seacock and the hose clamps and their condition as the hose clamps rust and break or the hoses dry out and get rigid and fracture or crack.

Lagoon Thruhulls and seacocks aren't Bronze or Marelon-they are brass! and by design are only supposed to last 5 years as 'approved by the stupid CE LOL

[Watercolor]

About 8 or 9 years ago there was a company that manufactured titanium hose clamps and was trying to promote them to the marine industry. The major issue at the time regarding titanium and boats dealt with the position of titanium on the galvanic scale as compared to other metals like SS and Alloy 836 (AKA leaded red brass, 85-5-5-5, Composite bronze, and ounce metal).

The reason why Allot 836 and 316 SS seem to be compatible is that they are very close on the galvanic scale. It is my understanding that the galvanic scale gap between titanium when compared to alloy 836 and 316 SS is significant, and the larger the gap the greater the corrosion rate.

Here is a site that discusses the galvanic effect of significantly different bronzes Alloy 836 (composite bronze) and silicone bronze in a highly technical gate valve.

Search | Corrosion Analysis Network

I'm not against using titanium, I was very interested and was in conversation with the company rep for the marine industry when I learned about this issue. The company abandoned the project, they said because of the sharp spike in titanium.

One of the issues that came to mind was how do you ground to a titanium thru-hull?

Just a bit of food for thought.