Home |
Search |
Today's Posts |
#1
posted to rec.boats,rec.boats.building,rec.boats.cruising
|
|||
|
|||
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
|
|||
|
|||
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
|
|||
|
|||
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.cruising
|
|||
|
|||
Seacock/Gate Valves
"Dave" wrote in message ... On Thu, 10 May 2007 14:55:37 GMT, "James" said: 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? Coupla things. West has some ball valves that will fit right onto the straight threads of the thru-hull. However for purists, that setup will run into the objection that the thru-hull may break as the result of galvanic corrosion when you try to close the ball valve. Current standards call for a flanged connection. (Not being that much of a purist, I replaced my gate valves this season with ball valves that screw onto the existing thru-hulls. The existing thru-hull has held up for 25 years, so I'm not too concerned about it.) One point, Dave: All through-hulls have a limited lifespan. Essie also has/had threaded through-hulls onto which seacocks are screwed, but I'm in the process of eliminating them. In a salt environment, Essie's through-hulls lasted 40 years. She is now in fresh water, and they still look and feel solid, but I do not consider that to be a permanent state. So far I have completely eliminated three of these through-hulls (head compartment), glassing them out and converting to a porta-potti setup, with the head sink discharge now being pumped out well above heeled waterline. Eventually I will eliminate EVERY below-water through-hull that I can. Ideally, I will have only two: seawater intake for the engine, seawater intake for the galley sink. But it's an unknown at this time whether or not I can get my cockpit drains to discharge above waterline. |
#5
posted to rec.boats,rec.boats.building,rec.boats.cruising
|
|||
|
|||
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. |
#6
posted to rec.boats,rec.boats.building,rec.boats.cruising
|
|||
|
|||
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 |
#7
posted to rec.boats,rec.boats.building,rec.boats.cruising
|
|||
|
|||
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 |
#8
posted to rec.boats,rec.boats.building,rec.boats.cruising
|
|||
|
|||
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 |
#9
posted to rec.boats,rec.boats.building,rec.boats.cruising
|
|||
|
|||
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. |
#10
posted to rec.boats,rec.boats.building,rec.boats.cruising
|
|||
|
|||
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/ |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Seacock/Gate Valves | General | |||
Seacock/Gate Valves | Boat Building | |||
Seacock/Gate Valves | General | |||
Seacock/Gate Valves | Boat Building | |||
Seacock/Gate Valves | Cruising |