Gate valves - bad rap?

[Fred Ficarra]

Jim, The cause was lack of oxygen.

As soon as I read your post about not moving the water, I knew what was going to happen. It's text book stuff.

 

[Garry @ S/V TASHTEGO]

For Rick Dinon

That still leaves an unsupported valve on the end of an unsupported thru hull. Once again, what will you risk to save 50 0r 60 bucks in a boat for which you paid somewhere between maybe $10,000 and $250,000? Cost benefit wins the arguement even if its just the benefit of knowing that your installation is first class.

 

[Rick D]

To Garry

I don't disagree necessarily. You can purchase ball valve sea cocks assemblies that some believe are better than tapered-shaft traditional valves. See this link http://www.jamestowndistributors.com/ak/Plumbing/Seacocks/Buck_Algonquin_Seacock_fam/index.htmlHowever, using a valve with matching threads to a screw-down through hull fitting with the proper backing is acceptable practice for marine below-waterline fittings as far as I know. The only thing you may be giving up is the ability to put retaining screws into the flange. Otherwise, it's exactly the same assembly, no? (Just re-read your post and you said the valve is unsupported in this construction.) Well, it is true the valve casting is not tied to the hull, but if you use a valve with the proper tread match to the through hull, you have seated the valve on to the through hull, so I guess the risk would be that the through hull itself would break. That must be some degree of higher risk, but suppose it is a question of how much.http://www.jamestowndistributors.com/ak/Plumbing/Thru_Hull/index.htmlRick D.

 

[Fred Ficarra]

Gord, we need you! (again)

How many of our boats are sinking because of unsupported ball valve through hulls, compared to boats with traditional seacocks?

 

[Gord May]

Don't use unsupported Ball Valves

I’ve been more or less satisfied with the negative advice offered here, on NOT using Gate Valves , nor Stainless-Steel (underwater).According to the BoatUS Article “Why Boats Sink” , Undeerwater Fittings are the single most common cause of sinkings.http://www.boatus.com/seaworthy/sinking/default.aspReason ~ PercentageUnderwater Fittings ~ 50%Rain and Snow ~ 32%Fittings Above the Waterline ~ 9%Poor Docking Arrangements ~ 8%Other ~ 1%See also the BoatUS Article: http://www.boatus.com/seaworthy/swmbs.aspand Boating Magazine’s “30 Ways to Sink a Boat && 29 to Stop It”http://www.boatingmag.com/article.asp?print_page=y&section_id=8&article_id=504&page_number=1Bronze, Marelon, or (perhaps) Titanium are the preferred materials for SeacocksBelieve it or not, Titanuim Valves are not all that expensive, comparted to Bronze.Titanium is 40% stronger & 40% lighter than stainless steel and most important, titanium is very corrosion resistant.Listed below are some, but not all forms of corrosion that have virtually no effect on Titanium in a seawater environment:* Cavitation Corrosion* Crevice Corrosion* Electrochemical Corrosion* Electrolytic Corrosion* Erosion Corrosion* the dreaded Galvanic Corrosion.http://www.titan-marine-hardware.com/index.htmTitanium Thru-Hulls: http://www.titan-marine-hardware.com/titanium-thru-hulls.htmTitanium Hose Clamps: http://www.titan-marine-hardware.com/titanium-hose-clamps.htmQ: I asked “Titan” what they recommended to use for Seacocks with their Titanium Thru-Hulls. I would understand their (following) answer to be an interim recommendation only.A: Hello Gord, actually we're developing a line of Titanium Seacocks/Ball Valves that should be available mid-2005. Titanium will not corrode in seawater as you know, and other metals will still have their Galvanic corrosion issues, but not the Titanium. We would recommend using the Marelon as no corrosion issues would exist. However with composite materials the issue of melting in any fire situation exists, and you need to be careful with exposure to sunlight, as I'm told the material degrades under those conditions.Best regards, Hugh Richards

 

[Fred Ficarra]

Thanks Gord

Good scoop. In reading the info I learned that the boat US survey was of only 100 sinking's. The examples of a thru-hull failure were limited. The only way one was damaged was by putting a cheater bar on a frozen seacock. That would be one of those cases where we hopefully know our abilities and limitations so as not to do something stupid. The cheater bar method of freeing a stuck seacock was the only example to recommend the bolt-on models. Seems to me that my setup is pretty safe. All valves are Marlon and protected from flying objects. Thanks again Gord.