Shutoff valves. open or closed?

justsomeguy · Nov 4, 2015

Justin_NSA said:
Where's the logic in closing them when you pack up and leave? What am I missing?

If you never operate the valve, will you be able to when needed?

Don S/V ILLusion · Nov 4, 2015

The conventional wisdom is to always close all thru hulls when leaving the boat. The value(s) themselves rarely fail but the clamps, hoses and fittings are all weak points.
If you require evidence, statistics indicate more boats sink at the slip then not...

Nothing is going to "overheat" or "drain" simply by closing a valve. Further, the valves can "freeze" thereby making them inoperative unless they are used frequently. A corroded valve can break.

Moral of the story - there are numerous reasons to close them and none to leave them open.

capta · Nov 4, 2015

Very, very rarely will a thruhull leak. Almost always it is a hose or hose clamps that go, beyond the seacock. Obviously, you can not operate water cooled equipment with the seacock closed, so I must be missing something there.
Many who only use their boats occasionally shut all the seacocks when they leave the boat and that sort of mystifies me when it comes to cockpit drains and the like.
As a full time liveaboard, the only time our seacocks get closed is if we are working on a line connected to it. I have yet, in over 50 years, to come back to the boat and find a line leaking, other than fresh water, so sometimes I'll shut down the pressure water pump.
It seems to be a personal choice based on how secure one is with their plumbing, I guess.

Don S/V ILLusion · Nov 4, 2015

Justin_NSA said:
Good feedback. Aside from working the valves so they don't freeze up, I'm not reading any other good reasons.

Read again. You missed something.

The overheat scenario would be forgetting to open the valve before starting the engine. Hence the argument for leaving it open.

interesting perspective:
Rather than remember to simply open it, take the chance of sinking the boat..

Sometimes, it seems all we can do is shake our heads when people ask for advice and then chose to ignore it. Why bother?

Don S/V ILLusion · Nov 4, 2015

Justin_NSA said:
Maybe I'm dense but where exactly would tne risk of sinking occur? The valves are ABOVE the water line. If there are bad connections or loose clamps below the valve, shutting it won't help. It's a simple physics law. Aside from that you just mention 'conventional wisdom' and 'statistics'. I'm not ignoring you, I simply don't see your point.

How are your AC and engine intake seacocks above the W/L?

Maybe I wasn't clear but I thought we were talking about those.

Charles Erwin · Nov 4, 2015

Evidently you use the term "shut off valve" to means a valve through the hull above the waterline whereas most folks took you to mean "sea-cock" which is a valve and through hull below the waterline.

Have to go now because someones boat is mostly submerged at his mooring. Apparently the sink drain hose got knocked loose from the sink, fell over and flooded the boat.

Charles

Benny17441 · Nov 4, 2015

Well you could generalize that by shutting all valves you are providing your boat the best protection. The reality is that we are faced with different size valves, at different locations servicing different appliances or fixtures. These appliances or fixtures can carry different risk of failure considerations. Inevitably the issue of convenience vs. safety will come up. I believe that the first line of defense is the frequent inspection and timely replacement of clamps and hoses and fixture seals. I say first line because at some point you will need to open them valves and safety is most important when you happen to be aboard. There are valves that because of their location it could be very bothersome to open and close every time you use the boat. When talking about the head (toilet) water intake I always close these valves as the seals on these units are unreliable. On the other hand the engine raw water intake always remains open so if someone should crank the engine up it will not burn the impeller. If I need to close I will lay the boat keys on the handle as a reminder. The sink drain is a large valve but as long as the hose and clamps are verified to be in good shape it poses a small risk. I would close the A/C intake valve if it was located in a convenient location but otherwise not. One thing that is important is to exercise them valves with some frequency; inspect and exercise. Of course if you are facing a hurricane or storm go ahead and close all. As you can see different people have made up different rules that suit themselves and you should make up your own. Oh on the A/C if you happen to start the unit with valve closed it is designed to shut itself off with no damage. Make a routine and follow it. The first line of prevention for a boat sinking at the dock is the neighbors and people around it and not any bilge pumps or valves.

capta · Nov 4, 2015

Justin_NSA said:
Both have a vertical piece of hose between the thruhull and the valve. The AC system is right underneath the vberth pane. I think it would be wise to regularly check fittings and hoses, especially on systems that don't consider water level, but I think I'm safe. I should look for the possibiltity of syphoning too. I appreciate the feedback.

Every boat I've ever been on, the "valve" or seacock is mounted DIRECTLY on the thruhull. Whatever you have there is 100% unacceptable if what you wrote is correct! There must be NOTHING between the thruhull and the seacock that can fail.
From your description, though I may be presuming a lot, if these valves are standard "gate' valves like on a faucet at your home, these are also 100% unacceptable. You should purchase and install proper seacocks directly onto the thruhulls so that you can shut the valve at the water's source should you have a leak anywhere in the line. Thruhulls and seacocks rarely fail; gate valves often do.

31seahorse · Nov 4, 2015

Hello Justin, First, thanks for starting this conversation. Today we changed a thru hull fitting and the ball valve style shut off valve screwed onto it. Not a true seacock, but I'm sure many boats have this arrangement prior to connecting to some tubing to serve whatever needs to take in water or put out water or some other effluent. RE: Stuck ball valves.....The one I removed was stuck in the shut position. I hesitated to force it to open for two years prior to its removal. It was the thru hull valve for the holding tank pump out. Not likely to use it here in SW Florida, but I will think to operate that valve just to insure its operational if necessary. I often (but not always) shut the galley sink drain when we leave the boat at the dock. I seldom shut the raw water intake for the engine. I believe I will make a note to self: Get into the habit of closing all the thru hull valves when closing the boat. It will just be a new part of "putting the boat to bed", and as a wise man once said, "It couldn"t hoit!".

Unless we are missing something in your explanation, what capta is explaining is a concern to me about what you described. Pictures would help if you wouldn't mind showing what you are asking about.

hewebb · Nov 5, 2015

I keep mine closed when not on the boat. I hang the start key on the seacock for the engine intake to insure I do not start the engine with seacock closed.

Scott T-Bird · Nov 5, 2015

I've never understood that thing about hanging the key on the seacock. How is it that you just don't open it by habit, without need for reminder? Besides, don't you always check the discharge immediately after the engine fires up? The impeller isn't going to blow up if you momentarily forget to open it. Certainly, if you check the discharge by habit and find no flow, you'll shut down before the impeller is damaged (it's been soaking in water even while the seacock is closed).

Besides, the new Yanmar control panel eliminated the key. What would you hang on the handle in that case?

capta · Nov 5, 2015

Scott T-Bird said:
The impeller isn't going to blow up if you momentarily forget to open it.

If you start your diesel with the seacock closed, you will have destroyed the impeller by the time you can shut it down after finding no exhaust water through visual inspection, 99 times out of a hundred. It may not show for a while, but the damage is done and impellers do not self repair. So, if one does make this mistake, change the impeller on principle, just to be safe because it will fail soon afterwards, if not immediately.
Low water flow is not at all the same as no water flow, sucking against a closed valve.

Gunni · Nov 5, 2015

Scott T-Bird said:
Besides, the new Yanmar control panel eliminated the key. What would you hang on the handle in that case?

You hang a lock down/tag out on whatever disconnect you use to render the vessel's ignition inoperative. It goes to the the thru-hull valve when in operation, and back to the disconnect when you close the valve.