New Fangled Hoses & SEACOCKS!

[ebb]

Scott.
read the end of post #29 - follow instructions to the letter.

As post #28 intimates: THERE ARE NO THRUHULLS FOR INLINE BALL VALVES.
[ further research refutes this, at least for Marelon]

So you have to use the backing nut of the thru hull with suitable rubber compoubd to weld the fitting in place. Then you have to turn the NPT valve on to the NPS, which very soon stops turning. If the idiot keeps turning he or she screws up the threads on the thruhull fitting. And the glued in thruhull will start turning, And can possibly crack the threaded tube because it is thin and compromised by the very threads that make it a fitting. Remember, it is a fitting designed for a seacock. It is not designed to take a load.

Pipes and fittings come is thicknesses too. Schedule 20, 40, 80, 160 - same outside diameter but bigger number thicker wall. You might look for thicker wall thruhulls, if you will persist on screwing an inline valve on to your Schedule 20 thru hull fitting


It is possible that some manufacturer by now has a thru hull with NPT on top and a locking nut on NPS threads on the bottom. I don't know. It would be a no brainer to produce. NOW, if such an item does not exist, we have to assume some regulatory agency says they can't. If they can't then boat builders are installing inline valves illegally as seacocks, so is your yard manager, and your surveyor should go back to house painting. He's dead wrong too.

In a properly installed seacock, as specified above earlier post no b.s., The thru hull fitting can be said to FLOAT inside the seacock. There are NO loads on the fitting. There is NO backing nut on the thruhull when the seacock is there. You cannot compare the two installations, they are apples and oranges.

The seacock is installed first with the flange either lagged onto the backing block or thru bolted thru the hull.* The thruhull is then screwed into the unit and seated onto the hull if mushroom - or into the hull if flush. One merely screws the fitting in dry and out again for shortening until it fits perfectly. This is how it has been done for decades. NO strength is imparted to the seacock installation by the thruhull.


*If that mound under Bill's seacock is epoxy-chopped strand-cabosil mix and permanently affixed ie molded to the hull and if the seacock is glued on there with polysulfide or 5200, then IMCO it is good enough to screw some lags into the backing thru the designated holes - bolts being unnecessary.

Thank you.

[Scott Galloway]

I am not sure that I would use 3M 5200 to bed a seacock, You would have one heck of a time removing it later. Also, 5200 is a slow cure so unless you will be out of the water for an extend time, I am told that 5200 is not a good choice for below water applications. If you feel differently, I'd be interested in knowing your perspective. Perhaps 3M 4200 (fast cure) might be a better choice if you don't want to use polysuylfide.

Sorry if my last post gave the impression that I was trying to explain how to install a seacock. I was not. Indeed, I have never installed one. What I was endeavoring to do was to give one view of the dynamics of what might be happening inside a seacock to thru-hull joint as compared to what might be happening inside an in-line ball valve to thru-hull joint.

Here are a few photos that might help. The first two are from Groco's webpage and show the thread locations and types of threads for both seacocks and in-line valves, and also the mounting configurations.

[Scott Galloway]

Groco states,

"Groco does not recommend the use of in-line valves as seacocks for these reasons:

1. In line valves have no means of attachment tot he vessel hull or backing block...

2. if the connected thru-hull fitting become damaged or broken.... there would be no way to shut off the flow of water into the vessel.

3. In-line valves have NPT threads, which are not compatible with the NPS threaded thru-hull fittinmg (unless the thru-hull fitting is machined with 'Combination Thread'. Installing an in-line valve onto a thru-hull fitting will create a mismatch of threads resulting in minimal thread engagement between valve and fitting, and an unsafe installation. property damage and personal injury could occur. If you choose to install an in-line valve as seacock the thru-hull fitting ue dmust have 'Combination Thread.' "

Here is their in-line valve-as-seacock drawing: oops and
that didn't up-load, so I will continue with this series of photos at a later time.

[Scott Galloway]

Here is that drawing of the in-line valve installation:

[Scott Galloway]

I took my new Groco valve down to West Marine today and let it play with some Conbroco throughhulls, and hose barbs. I also had some fun with a Conbroco (Apollo) in-line valve. The labeled pictures tell the story. Please do not interpret the photos below as reflecting on the quality of any of the fittings. Instead these photos relate only on the use of in-line fittings vs. flanged seacocks for below-water, thru-hull applications.

First the seacock:

[Scott Galloway]

Next the hose barb on sea cock:

[Scott Galloway]

Finally, here is the in-line ball valve as seacock:

[ebb]

Scott, Really impressive bunch of thumbnails you have here. Good Ole Boat and Con Racey would have done well to run their 101s through you. Now we should condense this info a bit so that it's available for everyone.

You have proven that
a seacock is a BOAT fitting.
An in line valve is a pluimbing fitting.

Tell us more about "combination" threads. Who, what, where, how.


5200. Be sure NEVER to use this legendary adhesive as a caulk, especially for thruhulls and seacocks. Never use any kind of polyurethane tube-paste for something that eventually will come apart. IMCO thruhulls have to be changed every once in awhile. Stripped threads, corrosion, dezincing.

Boat Life polysulfide is my choice for the thruhull. But I really lean toward Dolphinite. Depending on how elegant the pad and holes turn out for the seacock, might even consider Dolphinite for the flange to pad. Those Grocos have dissimular metals in them and will have to be replaced or bebuilt sometime.

Dolphinite IS a bit beyond the pale (beyond the yard manager anyway.) Would be interesting to have opinions on this. On a very neat seacock install (precise holes, close tolerances, flat surfaces, 90 degree holes) I would prefer to use bedding compound. If all bedding compound is used, would definitely thru-bolt the flange. Now we're talking about something that can be disassembled easy! Guys complain about having to sawsall the thruhull off (mushroom) when it is rubbered in place. A flush t.h. would be a real chore!

Anybody? A lot cleaner stuff to use! Cheaper too. Smells good.

[Scott Galloway]

Ebb,

Sorry about the length of this thread, but the process of discovery was just that. As homework for my latest fast-course on this topic, I spoke today with the Groco factory. They now make all of their thru-hull fittings with "Combination Thread". By the way the ball valves on the one and one half inch seacocks are made of 316 stainless.

Groco recommends against installation of their in-line valves as sea cocks for below water application. Their one and one half inch sea cocks, which I have purchased, are recommended for below water applications. Their sea cocks have NPS threads on the bottom (seaward) end and NPT threads on top end.

They currently manufacture their thru-hull fittings with NPS threads with the exception of the top section of the threads, which are NPT threads to accommodate in-line valves for above water applications. This “Combination Thread” works well in the NPS threaded sea cocks manufactured by Groco.
These fittings have an "almost indistinguishable" transition from NPS to NPT threads near he top of their threaded fitting.

If you use this thru-hull in an above water application with an in-line valve, you need to be careful not to shorten the shaft, because if you did, you would be cutting off the NPT thread. In an NPS seacock fitting, the NPT threads at the top of the thru-hull slide right into the Seacock NPS threads without harming them since they are less wide than the NPS threads. Then, when more of the thru-hull shaft is inserted the NPS threads take over. If you have to cut the length of the shaft to accomodate your sea cock installation, it's no big deal to cut off the NPT thread section at the top of the thru-hull shaft.

Groco said that their products should not be bedded with 3M 5200, cause you can't get them off later but either ploysulfide or 3M 4200 are acceptable. I called 3M company a few days ago, and 3M told me that 4200 acts as a bedding compound only on bronze-to-bronze joints since on bronze, 4200 does not function as an adhesive. However 4200 does act as an adhesive on fiberglass, and that may cause you significant problems in removal, so there you go.

When setting the correct length for your thru-hull shaft for insertion into a below-water seacock, Groco's instructions say in part:

"
a. Step 1: …Measure the thickness of the hull and backing block together (Dimension A in the sea cock drawing above)

b. Step 2. Measure the total thread depth of the female NPS threads in the bottom of the seacock (Dimension B in the sea cock drawing above) Add A and B together.

c. If the thru-hull neck length exceeds this dimension cut the thru-hull length ¼ inch shorter than A +B. If the thru-hull length is shorter than A+B by more than ¼ inch, use a thinner backing block or use an Extra-long thru-hull fitting (Groco THXL Series)"

[ebb]

How bout that, Groco got all their bases covered.
Could be their combo thread thru hull is a little thicker walled to leave some meat for the pipe threads up top. It ought to be thicker if they are inviting poeple to use their t.h. with unsupported inline valves.

When you think of reaching in at an awkward angle to shut off a hole in the hull, wouldn't you feel a lot better bearing down on the handle of a bolted-in seacock? On a sailboat, where is the waterline anyway?

Thanks to Groco for their forthrightness. However, Marelon zeros out the marina corrosion issue. One maker makes both pieces. I haven't researched if Forespar make a combo thread thrruhull. Why gamble, install seacock.

Old timers have a problem with 'Plastic.' The nylon Marelons are almost indestructable. They will melt in a fire, but so will the A/C. One problem is that they should be exercised more often than an alloy because nylon swells a little in water. You sometimes read that Marelon is for above waterline use. Forespar makes no distinction. 338 will have a few Marelon seacocks.

Notice on that forum site above, one of the guys did a very clever thing, used monel bolts for the flange. Maybe if Groco supplied the bolts, you might be sure the alloys matched. But with monel the seacock will corrode before the bolts, therefor the hole is covered, so to speak. Groco seacocks have ss balls or chrome on brass balls. OhOh, galvanic action! You carry spares. Even if you don't do the maintenance yourself.

As I say elsewhere, there are so many bronzes and alloy formulas you really can't be sure you have your little ship covered in terms of same alloys surrounding the holes in your hull. Did not notice if Groco told us what bronze alloy their seacocks are made from. If they are using mid-century formulas like Bristol Bronze for their in salt water/marina seacocks (like manganese b.) we may be in for trouble. We have an idea how long they lasted in the past but that probably doesn't jibe with the shore powered marinas we're tied up to today.

Hooray for Groco, anyway. Anything from Spartan???

[Bill]

Just to make you feel good about Marelon, I've heard that the handles break.

[Scott Galloway]

Groco's sea cocks have 316 stainless steel balls. Less expensive sea cocks and valves by other manufacturers have plated balls in their sea cocks. The Groco factory rep explained it to me this way:

If you have your boat in the water in a marine environment, then you want the top of the line. If you keep your boat on a trailer and launch it in fresh water occasionally, you might want to seek a less expensive solution. I understood that Groco might be considering other products for this market.

Groco advises strongly against the use of in-line ball valves for below the water applications. Recently I was reading somewhere about static waterline (a parked boat) vs. (I think they called it) a "dynamic waterline" when it comes to making discernments about the choice of sea cocks etc. I suppose that if asked I would define an "above water thru-hull" on a sailboat as any place that you can tack or jibe to be able to stuff a plug into from outside the hull without having to get into the water. Then again, I have had days where I saw daylight coming up through my cockpit drain thru-hulls under sail, but those are not the sort of holes that I'd try to plug from the outside while under sail.

By the way, I have been thinking with some concern about the placement of a holding tank vent in relation to dynamic waterline. You don't want the thing in your face or near your bow cowl vent for that matter, but the rail is in the water so much that I wonder where you do put a holding tank vent, unless you ran it through the transom and that would not be pleasant when running down wind.

...oops off topic.

Groco and I did not discuss which type of bronze these valves are made of, but they do provide a bonding screw, and so now I have to figure out how on my OB Model Ariel I am going to deal with a zinc for these guys. I have a rudder zinc tied to my upper rudder shaft and a rudder shoe zinc connected to my lower shaft though the shoe, but I better search this site for zinc threads, or start one.

By the way, what appeared to be forty year old Wilcox-Crittenden sea cocks on my boat, although they were as green as my new boot stripe, were in great shape. One of them was frozen due to lack of use (a head valve that was capped after the original head was removed). No pink metal at all: solid bronze that looked like new. The yard cut the poor things from my hull, and once they were off, it was apparent that they were like new through and through.

Were I to do it over again, I would have removed, rehabilitated and reinstalled the head sea cocks, and I would never have removed the cockpit seacocks. Although there is a benefit to having 1.5 inch sea cocks on the cockpit drains for sure, I could have replaced a one and one eight inch fitting, and then used a couple of parts plus a Groco full flow hose barb to take me to 1.5 inches from one an 1/4. My point in saying this is that even with very old bronze sea cocks there was no indication of corrosion. On the other hand, corrosion in my rudder fittings and upper rudder shaft were evident. We have a hot harbor. A neighbor lost a rudder due to corrosion a few years back, and yet, my unbonded thru-hulls and sea cocks were just fine. MY Boiat has been in thsi harbor and this slip for at least ten years.

Groco stopped making their rubber plug seacocks in 1992, and I had two of those. Although undersized for my application, they were in perfect condition also. I had just dissambled, cleaned them, and and regreased them before the yard recommened replacement. The solid bronze parts and sea cocks were not bonded to anything, but the bronze was in like new condition.

Hmmmm Bill, I though Marelon was virtually indestructible except by fire. Even the very traditional Dan Spurr has used them, so although they seem somehow out of place on my Ariel. Mr. Spurr put some Marelon Seacocks on his Triton as I recall. See "Spurr's Boat Book". A must read for every Ariel owner.

If you are wondering how green that new boot stripe is, I just repained it today. The original job did not withstand three haulouts in less thn a month. So, take a gander. The green and red are paint of course. The white is pure original gelcoat:

[ebb]

Current practice is not to bond ie connect your underweter thruholes together. Since you ARE OUR researcher on this subject, maybe you can find substance for this. I believe skippers feel that marinas are so hot that it is better not to connect but to zinc.
[John, on the 'sink me zinc me' thread suczincly explains modern zincing]


I really don't think Marelon can be broke. The broken handle story has been around forever. It may be related to the screw that holds the handle on to the body which has been replaced by a fatter one for a number of years. But I don't know what "breaks."

Marelon seacocks cannot be taken apart for maintenance. The only m. you have to do is grease the ball by taking the hose off inside and outside when the boat's out. Once a year. Maintenance consists of 'cycling' the valve. The dirtier and more virulent your marina the more you turn the handle. Wouldn't this be the case for an alloy valve? Exercising the valve keeps the ball clean.

One Marelon guy says he has never had a problem even tho his valves are rather stiff. The handles are balanced in the sense that they project out both sides of the shaft. He doesn't LEAN on the long side but cups (my description) the handle providing up and down turning on the handle.

If you've forgotten to cycle your seacock for three years and you have live barnacles in the hole, and you use a piece of pipe to persuade the handle to open or close, something has to give. What gives maybe is the center(?) I'm going to check this out because I want to use Marelon on 338.


I have not varified this:
Forespar site talks of a "93 series" a heavier form of thruhull. If I understand it, you not only can get a heavier thruhull but also get one with STANDARD PIPE THREAD. You match the NPT with an NPT valve (not sure if that means seacocks also have that option.)


What this means is that you can get many more turns befor it snugs up. I'm going to call them and will ask. I can't see any reason for a pipethread thruhull going into a pipethread seacock - so they must be talking about the questionable practice of using an inline valve as a seacock. And providing a stronger thruhull with the proper threads.



OK. Just talked with Forespar. Yes the handles can break, cecause they are not exercised regularly and the balls load up. Head discharge seacocks calcify and must be REPLACED periodically. The same is true for sink valves related to what you put down the sink.

The 93 series of SEACOCKS were produced in response to new regs (But by whom didn't compute (ABYC?)
You purchase the seacock and thruhull as a unit. They are pipe-threaded ie both are NPT. The thruhull is pared down till it fits into the seacock depending on backing block height. This has to be the most secure setup ever.

For you guys who insist on alloy, maybe Scott can find out if Groco/Apollo/Spartan have a version of these too. It's a whole new ball game

[Scott Galloway]

Ebb,

I am not sure that I care to find out. In my still very uneducated opinion, it make no sense to have an NPT to NPT connection between a thru-hull and a sea cock. This does make sense when using an in-line valve, but a seacock must fit snuggly and bolt through or screw into its backing plate. The length of the thru-hull will depend on the measurements A + B in the above drawings. So unless they made a series of these thru-hulls in various lengths, one would be in the position of having to cut off part of the NPT fitting on the thruhull and rethread these things.

When I spoke to the Groco rep, we did discuss the NPT to NPT fittings on their thru hull to in-line valve option for above the water applications. He told me that they design NPT threads to turn by hand 2.5 to 3.5 turns. Having more turns is not OK, and having less turns is not OK. Then you get about another three turns mechanically (as I recall) with your wrench.

That makes a total of 5.5 to 6 threads engaged, and that ain't enough turns in my opinion for a below water and below valve application, despite the fact that many marine yards install in-line ball valves on thru-hulls in exactly this manner, and Groco themselves show you the best way to do exactly what they do not recommend which is to hook one of these NPT ball valve to NPT through hulls. Indeed even some surveyors accepot the use of these things as valid applications, and the ABYC may actually allow them (according to Buck Algonquin). However, Groco and many marine writers strongly recommend against doing this NPT to NPT ball valve to thru-hull thing below water, so why design a seacock that replicates this silly use of NPT fittings even if the NPT to NPT joint would be tucked away within the seaock body with all of it's glorious six threads engaged (you hope).

The idea behind an NPT fitting is that the taper in the male and female threads coming together creates the necessary compression to hold the joint together....provided that the joint will not be stressed laterally. And by the way, plumbers are not supposed to even do this NPT to NPT thing below ground in a fuel tank installation. They are supposed to use something called a swing joint to reduce the potential of ground-movement-caused lateral sheer severing these NPT to NPT joints. This taper is a good thing for most plumbing applications. The Groco rep says that finely machined NPT fittings if tightened correctly will hold without teflon tape or pipe dope. Pretty cool, huh? Well yes, but not were there might be lateral forces such as flying bodies, tool boxes or storage containers, boxes of canned beans, or spare parts that ypou might store beneath the cockpit in the vacinity of your cockpit thru-hulls.

Now in a traditional flanged sea cock, a different approach is used: A sandwich consisting of a sea cock flange with backing block on the inside and a thru-hull flange on the outside, fully engaged male and female threads along the full length of the A + B dimension (The depth of the threads in the bottom of the sea cock plus the distance from the top of the backing block to the outside of the hull less 1/4 inch), and lots of bedding compound between all of the invloved parts creates the compression necessary to hold the system together. The NPT Threads in this application would offer no advantage that I can determine, would make installation more difficult, and actually serve to weaken the joint by reducing the number of engaged threads.

Now having said all of that, the Groco rep also advised me that the industry is changing rapidly and this means that using conventinal wisdom is somewhat dangerous without consulting your manufacturer and installer (or yourself) about the design of the parts and the installation procedures and material to be used. For instance, Groco has gone from straight thread thru-hulls to something approximating "bastard" NPS threads and finally at this point in time to their current combination thread, but their literaure doesn't overtly state that. And then there is my developing expertise which is based partly on reading writers who published books that predate the changes in the industry relating to thread depth... and also one manufacturer's strong recommendation with is current with their product.

For another instance, this business of which bedding cocmpound to use and coming to understand the cohesive and adnesive characteristics of various products such as 5200, 4200 and various polysulfides is not that simple. You can download the detailed 3M technical sheets and still not undertand what you are dealing with. I had to call 3M to dissover that:

1. 4200 does not act as an adhesive on bronze, but only as a sealant.
However, getting it off fiberglass is another thing all together.

2. The jury is still out on the interaction between 4200 and certain plastics such as PVC and nylon. 3M told me to test the product before using. Prudent advice, but what are the standards for that test? Does your marine yard know the answer? Do you? Wanna be a guinnea pig?

Back to threads, your installer (or you) could very easily assume that a part has one sort of thread and find that the truth is far different. So consult the manufacturer and your yard before you install. If you are using a yard to do the installation, and if you get the answer, "Because we have always done it this way," then take your boat and sail rapidly to another yard, assuming that your original thru-hulls and seacocks are still installed. It's a bit late to do so otherwise.

Certainly there is no substitute for hands-on experience when it comes to working with boats, but when the manufacturing environment is changing, being up to date with the technology is equally important.

[ebb]

Like I said, repeating Forespar, Buy the set. Seacock comes with thruhull. Probably comes with printed instructions for the yard manager to follow.

4200 is a polyurethane. I wouldn't use anything but marine polysulfide.

Strangely Forespar recomends any and all brands of marine adhesive including 5200. Will ignore that. but will order a set of the 93 series to see what it is. If you lag in the flange from the top with screws, it may mean you can take the seacock off from the inside. You could replace with a fresh one while under way (and a face full of ocean.)

What you do with the mounting is make sure (if you have the height room inside) that the thru hull fits exactly into the seacock as it comes from the box when it is screwed down to the backing plate - or flattened mound of epoxy. I would do this with any brand of valve, because repair and removal next time becomes easy, and therefor not something likely to be put off.

Scott, we are talking here about a flanged seacock (Forespar 93 series) that has straight pipe threads that engage the thru hull. If you get your A's and B's right, as you say, you will be able to turn that valve right down onto the backing. And have it TIGHT. And it is flanged so just about nothing is going budge it if it gets hit.

5 or 6 turns of matched pipe thread is pretty darn good for pipe and fittings. That is I think one half to three quaters of the threaded male portion (IT IS on the tailpiece that goes into the 1 1/2" Forespar inline valve I have right here. but it only feels right as I'm no engineer.) All the lands and grooves are touching in that small area. That's the advantage of pipe thread - you tlghten with teflon tape - and a little bit more.

The seacock screwed onto a straight thread thruhull is, shall we say, merely interlaced. It is only tight when gooped with caulking, no teflon possible here,
You would be able to go under your boat, and if you hadn't used 5200, 4200 or 3200, theoretically easily unscrew the thruhull. That's why you have so many threads, male and female, makes it unlikely. A NPT straight thread seacock is really held on by the flange fastenings. Believe it or not. Somebody tell me if I'm wrong.