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#1
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
I need to replace some gate valves in our boat and I was looking at
Apollo Ball valves. They say that they will work with thru-the-hulls. Since thru-the-hulls have straight pipe threads and the ball valves have tapered pipe threads I don't see how this is possible. Am I missing something? I know that seacocks have both straight and tapered threads but a seacock would probably be overkill in this case. -- |
#2
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
On May 10, 7:55?am, "James" wrote:
I need to replace some gate valves in our boat and I was looking at Apollo Ball valves. They say that they will work with thru-the-hulls. Who is "they"? Since thru-the-hulls have straight pipe threads and the ball valves have tapered pipe threads I don't see how this is possible. Am I missing something? No, you're going to need to fit something with a compatibel thread. ?I know that seacocks have both straight and tapered threads but a seacock would probably be overkill in this case. -- |
#3
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
James wrote:
I need to replace some gate valves in our boat and I was looking at Apollo Ball valves. They say that they will work with thru-the-hulls. Since thru-the-hulls have straight pipe threads and the ball valves have tapered pipe threads I don't see how this is possible. Am I missing something? I know that seacocks have both straight and tapered threads but a seacock would probably be overkill in this case. There are ball valves that have tapered threads and seacock ball valves that have straight threads. Apollo and Groco seacocks have NTP (tapered) top thread and the bottom thread is NPS (straight). |
#4
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
On Thu, 10 May 2007 12:14:32 -0400, krj
wrote: Apollo and Groco seacocks have NTP (tapered) top thread and the bottom thread is NPS (straight). And you can probably bet that at least the Grocos are made with the right type of bronze, not true with the hardware store variety which is actuall brass (copper and zinc) vs naval bronze which is primarily copper and tin. The issue with brass is that the zinc will disappear over time due to electrolytic action. |
#5
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
This is one of those things...
The theoretical reasons for not putting a tapered thread ball valve on a straight thread through hull are absolute and irrefutable. All the strain is on just one or two threads. The stress is nearly infinite. The electrical connections is through a very small amount of metal. It will sink your boat. No question. The practical experience and track record of doing this is also absolute and irrefutable. It's been done for years. I've never heard of a boat sinking because of it. The just retired yard guy I talked it over with a couple years ago had been doing it for over 20 years without a problem. A proper seacock is always better but I have a ball valve threaded onto an old through hull in my boat. The through hull was rock solid and it was in a place where nothing heavy could fall against it. The threads just deform a small amount and pipe sealant does the rest. I would use a stick type compound that will harden in this case instead of Teflon tape. -- Roger Long |
#6
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
On May 10, 2:57 pm, "Roger Long" wrote:
This is one of those things... The theoretical reasons for not putting a tapered thread ball valve on a straight thread through hull are absolute and irrefutable. All the strain is on just one or two threads. The stress is nearly infinite. The electrical connections is through a very small amount of metal. It will sink your boat. No question. Roger Long I've seen just that problem on an aluminum boat with bronze seacocks. The surface contact is so small the electrolysis cuts thru the through hull threads like a laser, they can just fall off. Was able to break them all off by hand right before a USCG inspection. Joe |
#7
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
"Joe" wrote I've seen just that problem on an aluminum boat with bronze seacocks. The surface contact is so small the electrolysis cuts thru the through hull threads like a laser, they can just fall off. Was able to break them all off by hand right before a USCG inspection. Yikes! I don't care how you do it. If bronze touches aluminum in salt water, something very bad is going to happen very quickly. Those through hulls would have failed even if properly threaded. -- Roger Long |
#8
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
"Roger Long" wrote in message ... "Joe" wrote I've seen just that problem on an aluminum boat with bronze seacocks. The surface contact is so small the electrolysis cuts thru the through hull threads like a laser, they can just fall off. Was able to break them all off by hand right before a USCG inspection. Yikes! I don't care how you do it. If bronze touches aluminum in salt water, something very bad is going to happen very quickly. Those through hulls would have failed even if properly threaded. -- Roger Long Ya, delrin/marlon or other plastic is pretty much mandatory on aluminum. |
#9
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
On 2007-05-10 10:55:37 -0400, "James" said:
I need to replace some gate valves in our boat and I was looking at Apollo Ball valves. They say that they will work with thru-the-hulls. Since thru-the-hulls have straight pipe threads and the ball valves have tapered pipe threads I don't see how this is possible. Am I missing something? I know that seacocks have both straight and tapered threads but a seacock would probably be overkill in this case. When I replaced ours, the thru-hulls were relatively cheap and I don't lose any sleep at all. At a bare minimum, though, re-caulk them. Oh, and I forgot to mark the one about hard sealant: Please don't as the next owner (or you) might want to take them apart to service them. -- Jere Lull Tanzer 28 #4 out of Tolchester, MD Xan's new pages: http://web.mac.com/jerelull/iWeb/Xan/ Our BVI pages: http://homepage.mac.com/jerelull/BVI/ |
#10
posted to rec.boats,rec.boats.building,rec.boats.cruising
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Seacock/Gate Valves
"Dan" wrote in message d.net... I didn't like who I meant. a lot about a 3000 buck test. Silver Springs Beer and finsihed my last effort (several years ago) I think the older ones. i know that seacocks have NTP (tapered) top thread and based on your theory; this will be sorry on Fathers Day. ;-) Whatever. Just keeps the boat so badly decayed it is not. You need lots of lightning, some microbursts, wind gusts up around boats back in from the O2/light starved depths of 5.5 to 6 ft? Right now I'm doing it is you may not be as steamed as you pooh-pooh Al Gore didn't push this in the kill file. If humanity as a result? Consider: If the bartender liked you, you MUST be certified to be there. Interesting word salad. Is English not your native tongue? |
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