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Gate valves and why we don't use them...

8K views 28 replies 11 participants last post by  jlprice 
#1 ·
I know I know... But I haven't had a haulout other than to cradle ship my boat and I still have one gate valve for the galley sink drain. It finally gave up the ghost today. You can turn the handle all you want forever and ever and ever :eek: I think the gate is lodged about 1/4 shut but of course there is no way to tell. So now I have to either schedule a haulout ASAP or hope the tides are right to dry out on the grid. Temps are around freezing so I can't do any glass work or painting. What a waste of a haulout...

Let this be a lesson to all you procrastinators!!! I know you are out there...

Replace crappy substandard valves ASAP!!!

Don't wait, DO IT NOW!
 
#2 ·
Do I understand correctly from your comments that you are in Alaska but don't haul your boat for the winter?
I changed all my gate valves in my 1978 27 footer this spring. It was a time consuming and fairly expensive venture but worth it in my mind. The gate valves looked brand new when I took them off but I still like the piece of mind I get from proper seacocks. They were in fresh water only.
Wait for Maine Sail to chip in here on this subject... it should only be a few minutes or so. He has an excellent site providing great instructions on how to do this. You shouldn't need to do any painting or fibreglass work but I used some West System epoxy to set my new bedding / backing plates.
 
#3 ·
Year round sailing in Alaska... What sucks is I had plans (always got plans...) to replace all the mushrooms and backing plates and install real flanged seacocks for every thru-hull. Now I get to just band-aid the problem and save it for later by putting a new NPT ball valve on the old mushroom.
 
#4 ·
At least it isn't on an engine cooling intake. Had a fellow sail club member recently tell me about the time a gate valve failed on a boat he was on, on the engine raw water intake. IIRC, the alternator bracket failed, the alternator fell off and broke off the raw water intake's gate valve's handle. They jury-rigged an alternator bracket (they were "at sea"), but did not realize that when the gate valve's handle was broken off, the gate fell closed. Luckily, it turns out impellers are usually tougher than we give them credit for.

Jim
 
#6 ·
There is nothing inherently wrong with using gate valves on a boat as a sea ****. The problem arises with the quality and design of valve used. What is commonly seen is a brass valve suitable for home use. There are high quality gate valves available in a variety of materials and construction methods. and they'll work just fine properly installed.

Small boat sea cocks serve their purpose well if maintained. Ball valves work easily but sometimes too easily if they're mounted to something that is subject to vibration and movement, like a boat. They can be either closed or opened inadvertently. Most of them commonly found are of no better construction than the lowly gate valve from the hardware store. Being a ball valve does not inherently make it safer...just easier to use.

There are no ships that use the same type sea cocks you'll see on boats; there's no effective way of operating them absent power. Gate valves are used almost exclusively, with the telescoping thread type being most common. Butterfly valves are often used but not for sea cocks. Butterflys are commonly power driven and suffer the same weakness that most, other than gate valves, suffer; a potential inability to close by manpower alone. Those long stems you see on gate valves are what gives them their mechanical advantage. Thus one man can easily open or close a valve that may be serving a 36" diameter pipe.

Here's a site I found buy simply googling gate valves: http://www.velan.com/products/pdfs/vel-api603-99-web.pdf
Further research will reveal the tremendous variety of suitable gate valves, even for your thru-hulls.
 
#8 · (Edited)
There is nothing inherently wrong with using gate valves on a boat as a sea ****.
There are several inhearant reasons not to use gate valves where a Teflon seated ball valve is available:

-No definite position indication
-mating surfaces will leak if damaged
-takes a lot longer to open or close
-prone to jam on backseat
-damage from freezing more likely
-more corrosion prone (more wear surfaces)
-more parts involved (more point of failures, as in my case)


 
#7 ·
I know I know... But I haven't had a haulout other than to cradle ship my boat and I still have one gate valve for the galley sink drain. It finally gave up the ghost today. You can turn the handle all you want forever and ever and ever :eek: I think the gate is lodged about 1/4 shut but of course there is no way to tell. So now I have to either schedule a haulout ASAP or hope the tides are right to dry out on the grid. Temps are around freezing so I can't do any glass work or painting. What a waste of a haulout...

Let this be a lesson to all you procrastinators!!! I know you are out there...

Replace crappy substandard valves ASAP!!!

Don't wait, DO IT NOW!
yep! still trying to figure out the best way to fix my situation. I can sail, but the cooling system is closed for now: http://www.sailnet.com/forums/gear-maintenance/47301-will-my-boat-sink-what-should-i-do.html
 
#9 ·
I think you'll find that subs use butterfly valves that are backed up by gate valves. Double valving thru-hulls is common practice on ships. I've never seen a square head **** or a ball valve on any ship..at least in a major piping system.
 
#13 ·
Thanks for that link, bubb2. The picture is illustrative of how you can have a three foot diameter gate valve and still allow one man to close it! It can also be noticed how the stem rises up through the wheel as it opens which allows it to be lubricated periodically. The packing in the stuffing box is replaceable and the box itself is adjustable for wear and compression of the packing to prevent leaks.

Here's a non-rising stem model approved by Lloyd's fro marine use.
http://www.johnsonvalves.co.uk/Data/Data Sheet No. 06.05 - IW3 Gate Valve.pdf
 
#14 ·
How did this thread turn into "Here is the gate valve I use on my 1020 foot ship?"

Anyways. I got another question for you all.

Here are the givens:
6 hours of working time on a tide grid
35-40 degree air temp. Water 42F.
Glass work not possible.
Any use of sealants questionable..

Gatevalve is non functional and stuck open.


Should I:
A: replace it with a standard bronze ball valve being careful not to tweak the mushroom and break its seal

B: Cut down the mushroom. Undo the nut on the mushroom. Carefully thread a Groco seacock on and hope for a good seal. If I do it this way I will leave the current backing plate in place which is glassed wood. One big problem is it is barley the size of the base of the seacock. I also could not thru bolt it at this time.

C: Do nothing and have a boat with an 1 1/4" thruhull that can't be shut for the next 6-8 months until the weather allows for a real haul out and glasswork.


Hmmm. I am leaning heavily to option "A" but these are my choices. I have a 12 foot tide noon in two days so hopefully I will be able to get a spot on the tide grid and get to work. If I miss this next tide window it will be another month before I can try again! Eek...
 
#16 ·
I think adding a second valve is probably your best temporary fix. If you try removing the existing valve and break the seal on the through-hull, you'll have an annoying and persistent leak that will put a strain on your bilge pumps and batteries. :)
 
#17 ·
There is no direct path to the bilge where it is so if it did leak the water would end up all over the cabin floor.... ick.... But due to space restrictions it isn't possible to add a second valve. Heck, it is hard enough to get in there and work on the first one. The closest thing to that idea that I though of was to remove the hose barb and cap it. This isn't satisfactory in my mind. I have a nice pair of vice grips that are meant for working on pipe I can use to keep it from moving. Worst case I can pop it off, get some fast cure 5200 and stand there in the rain and rising tide with a heat gun :)
 
#18 ·
Either leave it alone then or put a plug in the thru hull from the outside. I'm getting confused here. Are you worried about the gate valve rupturing, with the bonnet popping off and flooding the boat or are you concerned that you've a thru-hull you cannot close if necessary? If the former, then you need to replace it or plug it, period. If the latter, and the rest of the piping between valve and sink is in good condition, you can add another valve anywhere, even under the sink.
 
#19 · (Edited)
The problem valve: About 4" above is blocked. There is about 6" on either side to work with, and as you can see the area behind the valve quickly tapers off to nothing. This valve is about 12 - 18" below static waterline. The ball valve in front of it is for the holding tank discharge.



I am concerned about having a thru-hull that can't be closed. I also can't winterize the system properly. The sink drain is 1 1/2" exhaust hose that appears to be in good condition, but then it tees off. This is a really tight area. It passes through a bulkhead about 6" after making a 90 degree turn, and then under some cabinetry and then to the sink. The other problem is not being able to winterize the system. I usually pour RV antifreeze into the sink. It does get cold enough to freeze sea water here!

Would life-caulk cure in time? It looks like I am going to be on the grid for about 12 hours. The next high tide isn't high enough to float off. Weather looks like chance of rain. Highs 45 low of 36 Shorepower is available so I could use a space heater if necessary at least inside the hull.
 
#20 ·
Would life-caulk cure in time? It looks like I am going to be on the grid for about 12 hours. The next high tide isn't high enough to float off. Weather looks like chance of rain. Highs 45 low of 36 Shorepower is available so I could use a space heater if necessary at least inside the hull.
We answered this question last year in another post you made about tide grid & changing of seacocks.

Here's what I wrote last time after calling both 3M and Boat Life..

I called both 3M and BoatLife and spoke with tech support about cure times & launching. I did this because neither site really specifies launch time's or windows before launch and I would like to add this info to my article. Here's what I was told by each..

BoatLife: When I spoke with boat life they very clearly stated to me that a full cure of between five to seven days with Life Caulk is what they recommend before a launch. The tech support guy would not budge on this point even when I told him 3M 4200 and 5200 will finish curing under water. I could not get him to budge on this and he said tack and cure are two different things and cure times are very dependent on ambient temperature. He also stated that the air & hull temp can't drop below 40 degrees during the cure process and must be perfectly clean before application.

3M: I spoke with Tom about 4200, 5200 and 101. He advised against 101 due to it's very long cure time in a short window situation or regular 5200.

As for 3M 4200 & 5200 Fast Cure he stated that while they will still cure under water they don't advise running the boat, as in water movement over the hull, until cure has been completed because it can erode any sort of fillet or seal thus causing a leak and possibly moisture entrapment. I think a slow motor to your dock would not hurt as he was mostly referencing power boat failures.

3M also stated that a 40 degree minimum of both hull and air temp should be adhered to and that the lower the temperature the longer the cure time. The hull must also be bone dry & free and clear of any paint, dirt or oil when you are applying it.

3M's official policy on underwater use is to let them fully cure but this guy was being quite honest. He did say they have seen failures on quick launches that's why he advised NOT moving the boat after launch (no water flow across the hull).

Again, 3M's OFFICIAL LEGAL STATEMENT POLICY IS TO LET IT FULLY CURE BEFORE LAUNCH. I say this because I don't want people running around saying 3M told me it's perfectly OK to launch in one hour even though it probably is if you're smart about it....
 
#21 ·
To be the safest, I'd take the rubber hose off and plug that elbo. Then I'd cut a plug to knock into the mushroom thru-hull from the exterior making sure that it does not reach the gate valve inside. Winterize your system and address the thru-hull and new valve at spring haul-out.
 
#22 ·
Sorry MaineSail. I remember that thread but I keep getting mixed up by BoatLife's advertising. It is a good thing you actually spoke to them otherwise I might have taken their product descriptions too literally :eek:

Can be applied underwater for emergency repairs. Can be applied to damp surfaces.
and..
CURE: Since Life-Calk sealant is a moisture/temperature cure and requires the absorption of moisture from the surrounding atmosphere, an increase in the relative humidity or submersion in water will result in a shorter tack free time and faster cure.
 
#23 ·
Sorry MaineSail. I remember that thread but I keep getting mixed up by BoatLife's advertising. It is a good thing you actually spoke to them otherwise I might have taken their product descriptions too literally :eek:

and..
I think both will cure but I'd be more comfortable with a product like 4200 Fast Cure than a slower curing polysulfide given the water and air temps and I generally don't like polyurethanes but I think this is one application that supports a fast cure product.

What I would do is get your boat ready for the tide cycle and tied in place on a dropping tide. At this point, and after plugging it from the outside, remove the gate valve. If you don't break the original seal on the thru-hull doing this yee hah! If it works you still have enough tide to bring her back to your slip and call it a day and if it does leak you're ready for the tide. Even if you break the seal of the thru-hull it will most likely be a drip, drip leak not a gushing river. So you can wait for the tide and be redy to go the minute it drops below the level of the through hull. Fly fishing waders work well to give you more working time. I used to careen my lobster boats when I was younger so I know the drill..;)
 
#24 ·
Sounds like a plan Maine. I'll take every tool, material, & part possible to handle anything... Even the splash zone. The boat will start to settle at 11.5' and the thru-hull will expose at around 10' Start working then... I'll have 4 cycles to get it fixed before I will have to get off the grid or stay there for another month! Fun fun fun... BTW I had to get the darn thing Fedexed overnight because the big local marine store is shut down for inventory and no one else had a 1.25" freaking bronze ball valve. Gotta love Alaska. If I'm not too rushed I'll try to take some pictures so you can add a "What to do (or not to do) if you are a pathological procrastinator" section to your thruhull website..
 
#26 · (Edited)
sailboy,
You might try your local well-drilling supply house. 1-1/4" is a very commonly used pipe size in the water well industry. He may have only forged brass valves on hand but can get either bronze or stainless easy enough. Many of them sell products from these guys who you can see make all three types of ball valves, and yet others. Legend Valve

You might also consult Grainger, although you'll need a commercial account to order from them, if there's one in your area. Here's a list of a few of their bronze ball valves. http://www.grainger.com/Grainger/wwg/guideBrowseMatches.shtml
 
#27 ·
I've been following this with some interest. We bought a 1975 38' C&C in July and none of the gate valves work and the surveyor recommended they be replaced with ball valves. Its in the cradle now and I plan to replace the gate valves with ball valves. Can I remove the valve from the through-hull and put on a ball valve or is it pretty well guarenteed that the through-hull is going to spin and I'll need to remove it and rebed it? If that's the case, then, is a flanged valve better?
 
#28 ·
JLprice-

Is the through hull bolted or screwed to the backing plate??? If not, then yes, you'll probably spin the sucker when you're removing the valve.
 
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