New Fangled Hoses & SEACOCKS!
Anyone had any luck working with the white sanitary waste system reinforced hoses? The white stuff seems to be the only hose stock that marine stores carry these days other than reinforced bilge pump hoses?
The current challenge is trying to replace my clear plastic cockpit and sink lines with reinforced tubing.
I guess that the white stuff is very reliable, but how on earth do you get it to slide onto a pipe or through hull fitting? Soaking in hot water doesn't get enough hose on the pipe for a second hose clamp. The vertical distance between the valve and the downspout is short and the "T" to the sink must fit into that space also.
The white stuff says "1 1/2" but it sure doesn't slide very far onto a one and a half inch cockpit drain fiberglass down spout.
NPT = Not Playing That game on my sea cocks
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.
Another good reason to thru-bolt your sea cocks
Here is perhaps the most convincing reason that I have yet encountered to thru-bolt your flanged sea cocks....and implicitly another good reason never never to install one of those in-line valves in your boat in-lieu of a sea cock. If your boat is in a yard that alleges that in-line valves are sea cocks, you now have a reason to tell them why the two are different, and why you are sticking with Linn and Larry. The quote below is courtesy of Linn and Larry Pardee's marvelous web page:
http://www.landlpardey.com/Tips/Tips_2002_November.html
This post was dated Nov 2002:
Proper sea-cocks
"One of the jobs we have done at Mickey Mouse Marine this season, was to install a new marine toilet in a clients boat. We inspected the sea-cock and found it was, like many that are being used today, not connected in any way to the hull, with only the threaded portion of the thru-hull fitting connecting it to the boat. It was a sort of fortunate/unfortunate story. Unfortunately electrolysis had gotten to the thru-hull and it crumbled as we tightened the hose clamps because it was the only thing securing the sea-cock to the hull, if we pulled on the sea-cock handle to close it, that too would have broken loose. Fortunately the boat was dried out on our tidal grid and we could fix the situation before water poured in. But it reminded us again that this type of arrangement is potentially disastrous. Not only can electrolysis cause a failure, but a good whack from shifting gear could snap this connection. Check your sea-cocks to make sure they are bolted to the hull in such a way that should the thru hull fitting fail; you can still close the valve and keep water out. A very good and affordable proper sea-cock is made by Groco in the US."
Personally I am starting to see the wisdom in Ebb's desire to have no holes whatsoever below the static waterline.
3 Attachment(s)
Another Haulout - Another Approach
In 2010, I decided that it was time to try it again the right way. The capable and very professional people at Aquarius Marine in Santa Cruz removed my two Groco sea cocks and two inline ball valves along with all four thru hull fittings. The two seacocks along with three additional sea cocks were installed IAW American Yachting and Boating Association (AYBA) standards. Pre-drilled resin saturated plywood blocks were glassed onto the interior of the hull, and covered with additional layers of glass, and finally a layer of gelcoat. The seacocks were mounted to the resulting raised pads with bronze screws. I decided to have a fifth thru hull installed for the sink to eliminate the "T" in the port cockpit drain. I reasoned that this would prevent an accidental flooding of the cabin due to a blockage in the cockpit drain below the “T”. I now keep the sink drain closed unless I intend to use the sink for something other than a storage bin for items that I can reach from the cockpit. Shown in the photos below are:
1. The port-side cockpit drain before mounting of the seacock
2. The completed raw water line for the head.
3. The completed port-side cockpit drain and separate sink drain
lit'lgull's forespar marelon seacock
Insisted that I wanted a flush thru-hull, nothing sticking out.
Needed a 1 1/2" seacock and decided on the reinforched nylon one.
Convinced self that there were no bronze seacocks made with an alloy that was corrosion free.
A 1 1/2" Forespar seacock is a massive true flanged foot valve.
Its three 5/16" flange bolts are widely spaced and a fair distance from the thru-hole.
Those bolts are common available silicon bronze and imco nearly inert in salt water.
A338's hull in the flat of the bilge aft where I wanted the seacock was only 5/16" thick.
Built up the area with glass mat and epoxy to about 1/2".
This allowed chamfering the thru-hull hole, and chamfering the bolt holes.
The flat head bolt holes were chamfered deeper so that the heads could be covered with putty.
This would allow finding those bolts again in case the installation has to be taken apart.
The Forespar flush head straight thread thru-hull is rather long. It screws into the seacock about an inch or so.
The interior nubs that are used to turn a bronze thru-hull (just inside the head) are molded into the marelon at the far end of the fitting. Couldn't believe it, damned New Zealanders!
I called Forespar about their placement and the guy said that the two nubs were not for screwing the thru-hull in - "they're left over from the molding process." There are four small cut outs around the rim that are supposedly used to turn the fitting. Did they have a tool available? NO!.
But I felt at the time that I shouldn't shorten the thru-hull from what they supply.
That meant I had to build up a thick block of ply padding for the seacock. Almost two inches if I remember. Used pieces of various thicknesses of Meranti glued with epoxy.
But it left me with installing the damn thruhull and pissed at Forespar. Because I had already messed up the bitty recesses with dry fitting.
But this also meant that the flange bolts had a lot of meat to seat in.
And being through bolted and caulked with butyl means that they can be driven out later.
With a massive backing block this turned to be and if the bolt holes are all accessible, we might lag the seacock on from the inside, as Tony suggests. With the large fastening holes in the 1 1/2" seacock we'd be using, what, #16 screws? Plenty of grip. But through bolting is undeniably stronger, easier to remove - and mechanically fastens the backing structure/pad to the hull along with the valve. With any substantial backing the thru-hull hole and the three bolt holes imco don't present a weakness problem.
After the flanged seacock* is installed with butyl tape (which allows squeeze-out but also resistance to complete squeeze-out that would happen with the tube stuff - in theory anyway - that there will remain some waterproofing under the flange after bolting.
The seacock effectively shuts the hole. The thru-hull screws into the seacock independently from outside.
Used a lot of white thread sealer paste on the part of the thru-hull that screws into the seacock.
The long length of the fitting in the hole through the block has tube butly only part way but the flange is seated in the stuff. Didn't seriously cram it full. Fully screwed into the valve with thread paste it won't leak and if it does it won't matter - as long as I have buttoned the seacock in place.
Cut out a crude installing tool from 1/8" aluminum sheet. It extends down into the thru-hull to the nubs and also registers into two of the small cutouts in the rim of the thru-hull. Screwing it in and seating it slightly below the surface of the hull is a piece of cake. Unscrewing it years from now will be a different story.
The bolts holding the valve can thoerctically be driven out by turning the nuts off and using a driver pin to knock them out. Only the heads in the hull are caulked. NOT GLUED. If I have left enough room the seacock could then be unscrewed from the thru-hull inside. You'd have to be on the hard, of course. Then the thru-hull can be hammered out as it is not connected to anything. If I felt that a polysulfide sealant had to be used it'd be only under the head, not on the threaded shank. Would not seat the thru-hull with urethane rubber sealant.
If this works out in practice, we have here a non-corroding system that can be taken apart easily for replacement or recaulk.
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*Using an in-line ballcock valve for a permanent underwater hole in the hull is 100% WRONG. Even if Forespar shows this as an alternative in their literature you must assume that a ballcock valve shutoff on the hull
MUST ONLY BE USED ABOVE THE WATERLINE.
But imco NEVER used this way in any Areil/Commender.
The Forespar guy on the phone defended the ballcock/hull use by saying, 'a lot of builders use them this way'. That doesn't make the cheap-skates right!
I would not have any hole under water that depends solely on the thru-hull for its strength. The threading makes the thru-hull even thinner. IMCO the threads can be considered as SHEERING POINTS that a whack from the side can break. So even a drain above the waterline hidden away in a locker, almost inaccessible, for which you have a shutoff can get broke if it is a ballcock riding on the thru-hull.
Don't think that a hose clamped to a thru-hull drain is very clever either. Hose has tobe supported so it doesn't become a lever arm to break the ballcock off.
[way later edit: Groco (not Forespar) now has a ballcock conversion kit that adds a straight thread flange to the inline valve converting Groco brand ballvalves to a proper seacock.]
What have I missed?
Yeah, I know, keeping it short!:D
Professional Boat Builder
Thanks, Tim.
You'll find it in Archives under Attention to Detail.
Type of hose recommended for under water (nothing less than wet exhaust) is also mentioned
and just as important to how robust the installation is.
Steve D'antonio, the writer, has a test I've not heard before.
It's the STAND-ON-IT test.
If you can't stand on any part of your valve, hose and hole-through-hull system
it is not strong enough!
Groco adapter plate option
[11/24/10]
Chance at 'Commander #256 (Ceili)' is installing a bronze Groco system using a patented flanged adapter of Groco's that allows an inline ballvalve to be used instead of a seacock.
His installation is elegant and innovative.
imco THE BEST retro on thruhull systems using bronze.
Here in a blog is the end-all/be-all primer on this controversial subject we've been engaged in here...
Can't find right off who generates it but it has the ooooomph of MaineSail [CompassMarine]
or his sister.
Before you mess with that hole in your boat, look at this...
http://www.pbase.com/mainecruising/seacock_primer
Then be inspired by Chance's install.
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Can't find the author of this quote:
"Tradition is what you resort to when you haven't the time or money to do it right."
ain't that the truth