Seacocks & Thru-hulls

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E

Ed Schenck

Oversimplified?

Maybe I oversimplified. I bought both the thru-hull(straight threads) and the "seacock" at the same time. It looks like the one on the left in my previous post. I did notice the "NPT" but believe that is a typo. I have another one to install sitting on the boat and will check this weekend. I can tell you that the body screws all the way down onto the thru-hull. Well at least to the end of the threads in the body. The reason that I bought both the thru-hull and seacock as a package is due to size. On my H37C the engine and head thru-hulls are 3/4" and I could not find a "seacock" to fit. The new ones are bigger, 1 1/4" maybe? I know I have to fill the old hole and redrill to install. I also know about tapered versus straight threads. I have a ball valve on a thru-hull right now. If it is not REAL tight it leaks. And when you get it REAL tight the handle is likely to be where you cannot open and close it. But I have not had the problem of only getting three or four threads.
 
J

JCAL

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Dec 14, 2008
81
Hunter 27, 1990 Lake Charles
Seacocks or Ball Valves

The issue that insurance companies and surveyors express concerning the Seacock (ball valve) vrs standard ball valve is not the ball or throat of the valve but the diference between the threads and the ability to attach the seacock to the hull other than just the thru hull fitting. The seacocks I referenced which have are uni-body construction through the valve assembly and have a triangle base that will bolt to or through the hull. Also the threads on the base end (triangle) are the same as the thru hull and the thru hull fitting will screw into the valve over 1" approx. I have tried them both in the store and on my boat after I bought them. the real issue is not the ball valve but inablity to get proper fit for strength. Recommend you go to the local boat shop/store and try what I Have pointed out, I did. Do not be confused by the valves listed as "sea ball valves" The threads do not match the thru hull. You will find this also in the West Marine Advisory. You can have reasonable and acceptible security with the ball valve seacock or at least that is what I found through research via online, boat yard, and pratical application on my boat. I hope that your research brings you and your family and friends security and many great days on the water! Jim
 
J

JCAL

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Dec 14, 2008
81
Hunter 27, 1990 Lake Charles
Seacocks or Ball Valves

The issue that insurance companies and surveyors express concerning the Seacock (ball valve) vrs standard ball valve is not the ball or throat of the valve but the diference between the threads and the ability to attach the seacock to the hull other than just the thru hull fitting. The seacocks I referenced which have are uni-body construction through the valve assembly and have a triangle base that will bolt to or through the hull. Also the threads on the base end (triangle) are the same as the thru hull and the thru hull fitting will screw into the valve over 1" approx. I have tried them both in the store and on my boat after I bought them. the real issue is not the ball valve but inablity to get proper fit for strength. Recommend you go to the local boat shop/store and try what I Have pointed out, I did. Do not be confused by the valves listed as "sea ball valves" The threads do not match the thru hull. You will find this also in the West Marine Advisory. You can have reasonable and acceptible security with the ball valve seacock or at least that is what I found through research via online, boat yard, and pratical application on my boat. I hope that your research brings you and your family and friends security and many great days on the water! Jim
 
Rick D

Rick D

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Jun 14, 2008
7,139
Hunter Legend 40.5 Shoreline Marina Long Beach CA
OK, I'm Pipe-Thread Confused

about NPS and NPT, as to through-hull applications. Look at two items: the Marelon through-hulls and the Conbraco ones. Also the Marelon and Conbraco in-line ball valves. I used Boat US, West and Defender catalogs. Marelon: Defender says the Marelon through-hull is NPT. It does not say what the in-line ball valve threads are. It describes the in-line ball valve as a seacock but differentiates it from the flange-mounted ones. Boat US does not identify the type of thread for either piece. West does not identify the thread on the through-hull. They say the ball valves are NPS. Somebody's wrong. Conbraco (and West's brand not ID'ed): Defender says the through-hulls are NPT threaded. It does not say what the ball valves are, but describes them as "Shut-off Valve (seacocks)" that "install with a standard through-hull or sea-strainer". Boat US says the through-hulls are NPT thread, as are the ball valves. However, the ball valves "Should not be used as a seacock". Finally, West Marine does not say what the thread is on their through-hulls. They do say the ball valves are NPT, and add that they are "not intended to be screwed onto a straight-thread through-hull". Again, some real inconsistencies. So, what do you say? Is it possible that there are NTS ball valves that screw on to a NTS through-hull? Or, perhaps there are NPT through-hulls that accept NPT ball valves. But why then the recommendation to not use them as a seacock? With all the admonitions about not commingling NPS and NPT threads, we at least ought to be able to determine what's what. I think the manufacturer's web sites might be a place to start, but this sure is a mess for something this important. Also, I don't understand why a tapered traditional through-hull is better than a ball valve. Rick D. (Confused)
 
Rick D

Rick D

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Jun 14, 2008
7,139
Hunter Legend 40.5 Shoreline Marina Long Beach CA
OK, I'm Pipe-Thread Confused

about NPS and NPT, as to through-hull applications. Look at two items: the Marelon through-hulls and the Conbraco ones. Also the Marelon and Conbraco in-line ball valves. I used Boat US, West and Defender catalogs. Marelon: Defender says the Marelon through-hull is NPT. It does not say what the in-line ball valve threads are. It describes the in-line ball valve as a seacock but differentiates it from the flange-mounted ones. Boat US does not identify the type of thread for either piece. West does not identify the thread on the through-hull. They say the ball valves are NPS. Somebody's wrong. Conbraco (and West's brand not ID'ed): Defender says the through-hulls are NPT threaded. It does not say what the ball valves are, but describes them as "Shut-off Valve (seacocks)" that "install with a standard through-hull or sea-strainer". Boat US says the through-hulls are NPT thread, as are the ball valves. However, the ball valves "Should not be used as a seacock". Finally, West Marine does not say what the thread is on their through-hulls. They do say the ball valves are NPT, and add that they are "not intended to be screwed onto a straight-thread through-hull". Again, some real inconsistencies. So, what do you say? Is it possible that there are NTS ball valves that screw on to a NTS through-hull? Or, perhaps there are NPT through-hulls that accept NPT ball valves. But why then the recommendation to not use them as a seacock? With all the admonitions about not commingling NPS and NPT threads, we at least ought to be able to determine what's what. I think the manufacturer's web sites might be a place to start, but this sure is a mess for something this important. Also, I don't understand why a tapered traditional through-hull is better than a ball valve. Rick D. (Confused)
 
J

JCAL

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Dec 14, 2008
81
Hunter 27, 1990 Lake Charles
Threads

I cannot speak for Marelon valve however I can speak for Conbraco and Perko ball valve seacocks I have them both. I went into a west marine store and tried them along with the standard ball valve and sea ball valve. The Conbraco and Perko ball valve seacocks have two type threads, the thru hull side are the same as the thru hull fitting and the other side are NPT. The Conbraco and Perko ball seacocks fit the thru hull fittings and the others don't, no confusion here about that. There may be NPT thru hull fittings however I could not find them. Put it any way you want this works and that don't. Good luck! Jim
 
J

JCAL

.
Dec 14, 2008
81
Hunter 27, 1990 Lake Charles
Threads

I cannot speak for Marelon valve however I can speak for Conbraco and Perko ball valve seacocks I have them both. I went into a west marine store and tried them along with the standard ball valve and sea ball valve. The Conbraco and Perko ball valve seacocks have two type threads, the thru hull side are the same as the thru hull fitting and the other side are NPT. The Conbraco and Perko ball seacocks fit the thru hull fittings and the others don't, no confusion here about that. There may be NPT thru hull fittings however I could not find them. Put it any way you want this works and that don't. Good luck! Jim
 
B

Brent Headberg

Ball Valves & Seacocks

Well, after reading everybody's comments on this subject, one thing has come out of it, I can see: The threads are the most important component to a proper installation, not the material. There have been many opinions about brass vs. bronze and I don't think that is really the issue since brass and bronze are very similar metals and would not create a galvanic reaction. I downloaded the catalogs and cut-sheets from Conbraco and noticed that you can order the ball valves with any kind of configuration you want on the threads (either end). Also, McMasters Catalog sells these valves in various configurations too. I guess it boils down to this: Whatever an owner decides to do is based on his comfort level and common sense. From the manufacturer's side, they do what is required by regulations and their liability. Thanks everyone for your comments. Capn' Brent S/V Elena Lua
 
B

Brent Headberg

Ball Valves & Seacocks

Well, after reading everybody's comments on this subject, one thing has come out of it, I can see: The threads are the most important component to a proper installation, not the material. There have been many opinions about brass vs. bronze and I don't think that is really the issue since brass and bronze are very similar metals and would not create a galvanic reaction. I downloaded the catalogs and cut-sheets from Conbraco and noticed that you can order the ball valves with any kind of configuration you want on the threads (either end). Also, McMasters Catalog sells these valves in various configurations too. I guess it boils down to this: Whatever an owner decides to do is based on his comfort level and common sense. From the manufacturer's side, they do what is required by regulations and their liability. Thanks everyone for your comments. Capn' Brent S/V Elena Lua
 
E

Ed Schenck

Wrong Brent!

I think. :) How would you screw a locknut or seacock down all the way to the hull with tapered threads? As I stated in my first post and has been written about since, I can screw the locknut and the body of the seacock all the way onto the thru=hull until they bottom out. Those are straight threads which I thought were called "NPS".
 
E

Ed Schenck

Wrong Brent!

I think. :) How would you screw a locknut or seacock down all the way to the hull with tapered threads? As I stated in my first post and has been written about since, I can screw the locknut and the body of the seacock all the way onto the thru=hull until they bottom out. Those are straight threads which I thought were called "NPS".
 
C

Carl and Juliana Dupre

Metallurgist Please Speak Up!

Hi, Brent. I am not a metallurgist, and I have kept quiet till this point because I really don't know what I am talking about, but here goes. I would worry about brass. I believe that brass alloys contains zinc. I believe that one of the fundamental differences between brass and bronze alloys is that bronzes do NOT contain zinc. With brass I would be concerned about galvanic action leaching the zinc out of the brass alloy matrix. You might find yourself with microscopic porous swiss cheese instead of solid brass after a few years. We have been told that brasses really do not belong in the marine environment. That's my proposal for possible "senseless myth of the day". Would someone who actually knows what they are talking about please speak up on this point? Thanks. Carl s/v 'Syzygy'
 
C

Carl and Juliana Dupre

Metallurgist Please Speak Up!

Hi, Brent. I am not a metallurgist, and I have kept quiet till this point because I really don't know what I am talking about, but here goes. I would worry about brass. I believe that brass alloys contains zinc. I believe that one of the fundamental differences between brass and bronze alloys is that bronzes do NOT contain zinc. With brass I would be concerned about galvanic action leaching the zinc out of the brass alloy matrix. You might find yourself with microscopic porous swiss cheese instead of solid brass after a few years. We have been told that brasses really do not belong in the marine environment. That's my proposal for possible "senseless myth of the day". Would someone who actually knows what they are talking about please speak up on this point? Thanks. Carl s/v 'Syzygy'
 
Rick D

Rick D

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Jun 14, 2008
7,139
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Carl and Juliana , Interesting Point

...and I believe that is exactly the issue with brass. See the West Marine comments regarding brass and bronze. I do think there is something called 'red brass' that may be acceptable, but that's from memory a long time ago, from a West Marine reply to a Practical Sailor review. Don't take my word for it. Rick D.
 
Rick D

Rick D

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Jun 14, 2008
7,139
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Carl and Juliana , Interesting Point

...and I believe that is exactly the issue with brass. See the West Marine comments regarding brass and bronze. I do think there is something called 'red brass' that may be acceptable, but that's from memory a long time ago, from a West Marine reply to a Practical Sailor review. Don't take my word for it. Rick D.
 
J

JCAL

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Dec 14, 2008
81
Hunter 27, 1990 Lake Charles
464 naval Brass

Bronze is the perferred metal to use however MBCOQQ-B-637A-BU-Alloy-464-1/2 hard Naval brass is acceptaqble. The Navy has used it for years. Jim
 
J

JCAL

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Dec 14, 2008
81
Hunter 27, 1990 Lake Charles
464 naval Brass

Bronze is the perferred metal to use however MBCOQQ-B-637A-BU-Alloy-464-1/2 hard Naval brass is acceptaqble. The Navy has used it for years. Jim
 
K

Kevin

Added Question?

Why are there lots of 1/2 inch thru hull fittings available, but a lack of seacocks smaller than 3/4?
 
K

Kevin

Added Question?

Why are there lots of 1/2 inch thru hull fittings available, but a lack of seacocks smaller than 3/4?
 
M

Mike H

added question

I found the same thing: no bronze seacocks smaller than 3/4". Yet my raw water intake for my motor is via a 1/2" thruhull. I found a marelon 1/2" seacock. It was the only one I could find.
 
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