Closing Stern Gland Seacocks

[PeterBoater]

I have always closed the seacocks on water-injected stern glands when the boat is not in use but have recently been given second-hand advice that these seacocks should never be closed. No reason/justification was given. I can't think of a reason but have I missed something?

 

[theoldsalt]

Sorry Peter I am confused.

I thought water injected stern glands were fed from the engine cooling system so where would the seacock be other than the main engine cooling seacock?

 

[macd]

Sorry Peter I am confused.

Glad I'm not the only one.

 

[PeterBoater]

They are small valves/cocks mounted on the gland that open/close the sea water supply from the raw water cooling system. As this water supply presumably goes out to sea via the stern tube I called them seacocks.

 

[prv]

All right then, they are small valves/cocks mounted on the gland that open/close the sea water supply from the raw water cooling system. As this water supply presumably goes out to sea via the stern tube I chose to call them seacocks.

I think people are confused because it's not normal to have such valves.

The only reason I can see for not closing them when the engine's not in use is that someone might forget to open them again. If you're the only person who starts the engine and opening them is part of your routine, then I can't see any harm in closing them.

I also don't see any need to close them, mind you, unless the plumbing is in shockingly bad condition.

Pete

 

[macd]

Wasn't trying to be sniffy, Peter, and I'm sure oldsalt wasn't, either. It's just that most of we raggies aren't familiar with such plumbing.

If seawater can flow through through them backwards (as it were) into the cooling system and the exhaust elbow is anywhere near or especially below sea level, I'd have thought it prudent to close the cocks, just as it would be prudent to close the main inlet seacock.

 

[sailorman]

They are small valves/cocks mounted on the gland that open/close the sea water supply from the raw water cooling system. As this water supply presumably goes out to sea via the stern tube I called them seacocks.

Is this what is called a "piddler" that you refer to

 

[theoldsalt]

They are small valves/cocks mounted on the gland that open/close the sea water supply from the raw water cooling system. As this water supply presumably goes out to sea via the stern tube I called them seacocks.

Hi Peter, that sounds most unusual. Viv Cox might be very interested in that design for his web site http://coxengineering.sharepoint.com/Pages/Sternglands.aspx

What make is your stern gland? Have you any photos?

 

[vyv_cox]

Hi Peter, that sounds most unusual. Vyv Cox might be very interested in that design for his web site http://coxengineering.sharepoint.com/Pages/Sternglands.aspx

What make is your stern gland? Have you any photos?

Yes, they do sound interesting and I would like a photo if possible. As others have said, I assume the reason for not closing them is the possibility that they might be forgotten. As a slower boat the feed to my stern gland is simply a vent, open ended above the waterline. No valves in them and I don't think PSS recommend them.

 

[macd]

...I don't think PSS recommend them.

Yes, from memory not needed for boats under 12knots. Is this a powerboat?
Of course we don't know whether it is a PSS, but perhaps something similar.

 

[PeterBoater]

No photos to hand but I'll try to get some on the boat. Searching Google Images for 'stern glands' is not recommended while you're eating!

I always close the main raw water intake seacocks and the aforementioned stern gland ones because somebody else with my type of boat had the misfortune of having an exhaust elbow falling off the engine due to a failure; it and the attached exhaust hose fell below the waterline, as all the seacocks had allegedly been left open you can guess the rest. Fortunately it was spotted some time later by a vigilant marina patrol. Hence my concern on hearing that the stern ones should not be closed; I will continue to close them unless I hear a good reason why not.

 

[vyv_cox]

Yes, from memory not needed for boats under 12knots. Is this a powerboat?
Of course we don't know whether it is a PSS, but perhaps something similar.

I checked the PSS instructions as a general guideline. Even for shafts of 100 - 150 mm they don't mention a seacock but they do advise that the installation plumbing should be done 'respecting the rules of underwater plumbing'. Which could mean with seacocks on what might be 1/2" nozzles.

 

[Sinbad1951]

I also have such a valve on my water injected stern gland. Have never closed it and would suspect that its function is simply there to close if there was ever a catastrophic failure in the water injection pipe below the waterline. Closing the valve would prevent the ingress of sea water from the shaft.