Engine raw water seacock - is it more important or vulnerable than any other?

[KompetentKrew]

I'm starting a new thread about this because I don't want to derail my existing one about my exhaust elbow, but I wanted to reply to AndrewB's comment there:

Very sensible to shut the raw water seacock before dismantling - is the implication that KompetentKrew does not shut this routinely? That's not so kompetent, KK.

Is the engine raw water seacock particularly special in this regard?

I don't close the seacock to the heads between flushing it, why should I close the raw water seacock between using the engine? Admittedly it wouldn't be much of an inconvenience to do so if I'm in a marina for a week or two (or even, as now, for a couple of months), but I never leave the boat for more than a few hours.

There seem to be plenty of people here that I'd expect you'd regard as competent who leave their seacocks open all the time:

• pvb: http://www.ybw.com/forums/showthread.php?443496-x#post5496390
• john_morris_uk: http://www.ybw.com/forums/showthread.php?237817-x#post2518632

I don't particularly want to rehash all those previous threads but, equally, I'm quite happy to exercise the engine raw water seacock on a regular basis if it's more warranted to close that one than any others.

 

[prv]

Is the engine raw water seacock particularly special in this regard?

No, but probably in the really old boats where this religious ritual began, it was the only seacock on board so became the natural focus for the devotions of the faithful

Pete

 

[scottie]

There are two separate issues here ie closing the seacock and ensuring that you can close the seacock

 

[prv]

There are two separate issues here ie closing the seacock and ensuring that you can close the seacock

Agree the latter is a genuine issue. I exercise mine a couple of times a season and there will be a detectable initial stiffness if the last time was a while ago. I assume due to fouling building up in the valve, and that if left too long the seacock would eventually become jammed.

Pete

 

[Sandy]

I open sea cocks when arriving at the boat and close them when leaving because:

• I've got into the routine (yes I do have a checklist)
• It allows me to check the sea cocks
• it keeps them "exercised"

The engine raw water seacock has a clever wee locking gate on it fitted by a brilliant mechanic.

 

[LittleSister]

The engine raw water seacock has a clever wee locking gate on it fitted by a brilliant mechanic.

What is this 'locking' of the seacock, and what is the advantage?

 

[doug748]

The engine and heads seacocks control the more complex systems on most boats so it makes sense, if you close any, to close them.
If you never close any it's a bagatelle as to them working or not when needed.
Using all of them now and again is good practice, in every sense.

 

[RichardS]

What is this 'locking' of the seacock, and what is the advantage?

Probably a gizmo to stop one starting the engine when the seacock is closed.

I close the engine seacocks when we leave the boat and return home to the UK. Before that they had been left open for 5 years. Don't ever do that as you might never be able to close them again. :ambivalence:

Richard

 

[vyv_cox]

I have not checked the original thread but it would make sense to close the seacock if dismantling the seawater pump. Otherwise, I open my seacocks in April and close them at lift-out, between August and October. The only exception is the toilet discharge cock that is closed when the holding tank is in use. I check that all of them work as intended before launch and grease the three Blakes ones.

 

[Ohlin Karcher]

Old boat..
Brand new raw water seacock: Always left open, unless the boat is laid up, afloat.
Ancient Blakes heads seacocks: Religiously closed after use, they are connected to an antique Blakes sea-toilet and could theoretically sink us!

 

[RupertW]

I open all seacocks I’m getting to the boat and shut all except the engine seacock when eventually leaving it for a few weeks. I keep it moving but always leave it open as the chances of a mechanic or a crew member starting the engine with it shut seems more likely than it and the hose above it failing simultaneously. The filter and first hose connection is above the waterline.

Like so many boat decisions we all weigh one unlikely risk against another so have no actual evidence whether we have made the right decision. The only evidence seems to be that seacocks fail only when someday has lost faith in them and decided to replace them. We then get the “it fell apart at the first bit of my sledgehammer” story.

 

[AndrewB]

I always close all seacocks (except cockpit drains) if leaving the yacht for a couple of weeks or more. Then tie a string on the morse lever to remind myself the engine raw water intake is shut. This seems such a simple precaution, which takes not 2 minutes, that it is hardly a matter of "weighing up the risks".

If you are not going to bother, I'm tempted to wonder why fit sea-cocks in the first place? In any case, even if they are there, chances are they will have seized or broken if you don't exercise them from time to time.

Incidentally, a few years ago a yacht sank in a marina where I was based, as a result of a failed hose clip on a seacock that had been left open. Oozing diesel then made a terrible mess. So it does happen.

 

[Sandy]

What is this 'locking' of the seacock, and what is the advantage?

Keeps the sea cock open or closed. No chance of accidentally pushing it the "other way". OK I know the risk is low but I like the feature.

 

[Daverw]

All my seacocks have locking catch built into the handle as standard

 

[graham]

I found those locking gates a pain as you needed both hands to open the seacock.One to hold the gate up one to move the lever.Ended up removing them.

 

[Spirit (of Glenans)]

IMHO AndrewB's post was in the context of dismantling the cooling system, whereby, on some boats, there would be an inundation if the seacock were left open.
In answer to the wider discussion that has developed; I am in the habit of closing all seacocks when leaving the boat, having been trained to do so from when I started learning to sail. It both exercises the valves and leaves nothing to chance.

 

[Stemar]

My engine seacock is fairly inaccessible, so it doesn't get closed as often as it should, but I do find that an assortment of shelled critters tend to move in, blocking things up over a couple of seasons, so keeping them out would seem to be a good argument in favour of closing. The argument against is that I'm not so good with checklists, so would inevitably forget to open it when I start the engine. I used to hang the key on the seacock when I closed it, but I've done away with the key, so I can't do it any more.

 

[AndrewB]

The argument against is that I'm not so good with checklists, so would inevitably forget to open it when I start the engine. I used to hang the key on the seacock when I closed it, but I've done away with the key, so I can't do it any more.

Avoid such problems by getting into the routine of checking that water is spitting out of the engine exhaust when the engine is started. It's not only a shut sea-cock that can block water flow.

Much better than panicking when the temperature alarm goes off as you are negotiating a busy waterway.

Honestly, I don't suffer from OCD, these sea-cock precautions only take a moment, it's not worth not doing them. If you have a sea-cock that is neglected because it is difficult to reach, then cut an access port - a neat, waterproof cover is cheap.

 

[barryhall]

If your engine is below the waterline or, more precisely, the water injection point into the exhaust is then, as I found on a previous boat, the only thing between a flooded engine (or boat) is the impeller in the pump. This can be alleviated by installing a syphon break however they can be prone to the valve sticking.

 

[KompetentKrew]

Thanks. Barry. The impeller on this engine is very accessible, so I should check it asap.