To close, or not to close, the engine seacock

[prv]

Kindred Spirit lives in a marina berth that dries for a short while on springs. The engine intake seacock is not the most accessible - reasonable in an emergency, but once I rebuild the bunk it's under, a bit of a faff for routine use. I'd like to leave it open all the time, but there are two possible reasons not to:

1. All the water could fall out of the hose, and not go in again when the tide comes back, resulting in running the engine dry. The highest point in the system is the strainer, which is a couple of inches above the waterline. If you open it while afloat, the water stays in the strainer body. My dad (with whom I share the boat) is very keen on there never ever under any circumstances being any air in the intake hose, and closing the seacock before drying out is therefore mandatory. I'm of the opinion that the pump will be able to pull through a brief bubble in the supply without any trouble; it starts off wet as the hose from strainer down to pump never empties. The pump is new after an engine overhaul.

2. The hose could detach itself from the seacock and flood the boat. Strangely, my dad is terrified of this happening with the engine seacock, but is apparently unconcerned by either of the toilet seacocks, the cockpit drains, or the galley sink, all of which are left open. I can't really envisage this happening, since the hose was an incredibly tight fit on the nipple (would need to be cut to be removed; it's probably a size too small really) and is then secured with two good jubilee clips. The pressure differential in the joint is as near zero as makes no difference (the intake is inches below the surface) and the seacock is in its own partitioned-off space with no stowed gear to molest it. It's hard to think of anything which might cause the hose to separate.

Thoughts?

Pete

 

[john_morris_uk]

There are lots of people with some fairly irrational fears about seacocks and I am not sure that any argument put forward on this forum is going to change your dad's mindset.

There is no reason why the impeller won't pull through seawater from a TOTALLY emptied out seawater hose (in practice it won't empty out completely - only the hose leading down to the seacock). After all what happens when you first launch the boat since I assume that you don't have to prime the seawater intake to get the engine cooling to work? Therefore a small bubble of air is going to give it no problem at all. However impeller pumps don't like being run dry for long - and I always makes sure that there's lots of lubricant on the blades of our impeller when I first start the engine after our boats just been launched and the system is empty.

Regarding sea cocks, I expect there are people on here who will think that I am totally irresponsible as I leave most of our seacocks open 365 days a year. In fact the only time some of them get closed is when I go round them checking that they are still working OK. I agree that double clipped hoses don't usually jump off for no reason, and some of the seacocks have to remain open - eg our cockpit drains...

Regarding your situation - I suspect that you will just have to put up the foibles of he who pays the bills (or his share of the bills).

 

[Severnman]

If you get in the habit of closing all your seacocks you WILL have to open them again for routine operation. This exercises them which is good maintenance. You will also have peace of mind knowing that you will be able to operate them as required and that they wont be siezed!

 

[prv]

After all what happens when you first launch the boat since I assume that you don't have to prime the seawater intake to get the engine cooling to work?

If I recall correctly, the system was still full of water from having run up on shore to make sure we'd be able to motor away from the lift. I had all the seacocks closed as we went in (to minimise the number of potential simultaneous leaks to deal with - in fact there were none) which held the water in the engine system. If we went out and in again tomorrow, yes, dad would carefully prime the system with a jug into the strainer before starting up.

There are lots of people with some fairly irrational fears about seacocks and I am not sure that any argument put forward on this forum is going to change your dad's mindset.

Sadly, I think you may be right. I would feel more assured in my disagreement knowing that others saw it my way though

Pete

 

[Latestarter1]

John Morris, a voice of sensible reason.

I have never been asked to survey a vessel damaged by sea cocks being left open.

However I have looked at countless boats damaged to the extent of being written of due to sea cocks being shut. Worst case was brand new vessel in France, exhaust system went on fire writing off one engine and the complete interior leading to constructive total loss. Issue in this instance was that experienced owner never shut of his sea cocks, however technician had visited the vessel to carry out work and shut them prior to securing the vessel.

Legal wrangles lasted for several years, servicing dealer argued 'accepted custom and practice' as well as claiming that it was in vessel insurance clause. Most of the burden fell to dealers insurance company, with a very small portion blame against owner for not confirming that cocks actually open as part of his pre-flight checks.

As for my own vessel, memory all used up due to age, as mentioned on another post. I leave mine open

 

[dukes4monny]

I close all seacocks when leaving her unattended. When she's been out of the water, prior to launch I close the main engine seacock and prime the strainer, that way I only have to open the seacock once she's afloat.........

 

[dukes4monny]

However I have looked at countless boats damaged to the extent of being written of due to sea cocks being shut. Worst case was brand new vessel in France, exhaust system went on fire writing off one engine and the complete interior leading to constructive total loss.

An interesting point.......I am very careful about my checks of seacocks etc., but am acutely aware that others aboard might not be. I do wonder whether fitting a flow sensor (with alarm) on the raw water inlet is a good idea?

 

[Bosun Higgs]

Your dad is being irrational but you can't tell him that without getting into an old bull / young bull situation. So either live with his rules or quietly " forget" each time. "Sorry Dad, I'll try to remember next time "

I never shut any of the seacocks. With the boat on dry land, the engine water pump if in good nick will suck up water maybe 6 ft lower than the bottom of the hull irrespective of the air in the system. I know - mine does so.

 

[Deleted member 36384]

Why Leave A Hole In Your Hull?

I keep my seacocks closed. The engine raw water intake and exhaust are opened when I step on the boat and closed when I leave. The rest remain closed until needed and closed after use. Its not born out of paranoia, its just a practice I have adopted over the years due to water from the loo and sinks entering the boat. Its more to do with avoiding inconvenience than reducing risk.

From your own perspective it could be considered that there is a greater risk to the seacock jamming when needed due to debris from the mud, so closing might be a prudent thing.

A problem might present itself if you had partial plugging of the inlet. Then you may fine that the impeller can not lift the sea water through this restriction as well as over come an air gap. Of course this blockage could be present irrespective of the position of the sea cock. You may find that impeller wear and tare would be higher if every time you start the engine after a dry out it runs dry for a second or two.

At the end of the day I personally don't see the point in leaving my own boat unattended with a hole in the side that has the facility to be closed off. Having said that I blew the exhaust hose off the manifold after starting the engine with the exhaust valve closed. So much for prudence!

 

[chriscallender]

I prefer to close the engine seacock - not because I'm worried about the boat sinking but my usual startup procedure is to start the engine with it closed and then open it immediately - my concern being filling the exhaust water trap and getting sea water in the engine if she is slow to start after not having been run for a while. I always open it immediately the engine starts and then check the exhaust for water flow (... apart from the one time I didn't, that was slightly expensive ;-) ).

Another question, what is the need for double clipping hoses. My thinking is that if they are going to magically jump off with one clip (eg because they are badly secured) then they'd probably manage to jump off with 2. Surely one wide hose clip has the same grip as 2 narrow ones?

 

[Monique]

I close all mine when unattended. Opened before sailing except for Heads, sinks etc which are closed while under sail.

GL

 

[doug748]

I normally close the engine seacock, tho I do leave some others open - cockpit drains are a prime example.
It is easy for me and I don't know how I would react if it was difficult, I suspect I would still close it. There is a lot of associated stuff attached to an engine and many bits could fail in a leaky way.
BTW I always lift a floorboard when the intake is closed and never replace that floorboard wihtout turning the cock on.

 

[magic-martinh]

As above(Monique). Minimal risk and very little effort. I can't imagine being incharge of a boat and not double checking the raw water seacock.

 

[dovekie]

Potential corrosion of the clips themselves is the reason for double clipping I have always assumed. One might corrode and snap, but two is unlikely?

 

[TWINSCREW]

Morning, I think the double clipping of all hoses is more a requirement of Insurance Companies or Surveyors than boat owners, it was a condition of my last survey.
I had an incident some years ago delivering a yacht from up the hamble, lost wind off Calshot and started the topsail, engine warmed up the compartment and a badly fitted engine intake hose (stretched to fit) warmed up and parted company with the seacock,first I knew was wisps of smoke coming from the bridgedeck area, turned off the motor to hear water gently filling the bilge... I always turn all seacocks off..

 

[LORDNELSON]

Sea cocks

Mine are all closed when the boat is unattended and all open when attended. Main reason is I wonder what insurers would do about a claim for sinking from an (unattended) open sea cock. In common with most other small boat sailors upon starting the engine I look over the stern to check that cooling water is coming out of the exhaust.

 

[mattnj]

i use to leave mine open...until recently, when the bilges were full and pump was running when i got onboard (after a week)
after investigation there is a corroded raw water fitting hidden away that was leaking away slowly, could have been a lot worse if it was anything more than a fast drip....amazing how quickly it rusts away when it leaks too, this looked fine in October when last checked (need to remove a load of bits)

they all get closed now, and i remove the engine battery switch thing and put it by the raw water inlet, so it is very hard to turn batteries on without water first.

 

[pagoda]

Your dad is being irrational but you can't tell him that without getting into an old bull / young bull situation. So either live with his rules or quietly " forget" each time. "Sorry Dad, I'll try to remember next time "

I never shut any of the seacocks. With the boat on dry land, the engine water pump if in good nick will suck up water maybe 6 ft lower than the bottom of the hull irrespective of the air in the system. I know - mine does so.

I do shut seacocks if I'm not on board, and the engine seacock when "finished with engine" . At least you then go in there to open it and have a check round the engine at the same time. Sailing - I keep pretty much all shut unless the heads are needed.

I found the water pump was quite capable of lifting from a large drum of water about 5 feet below the prop, as I ran the engine from this to make sure the raw water side had antifreeze in it this last winter. And it happily lifted and disposed of a few air bubbles in the process. Worked fine.

I don't think anybody honestly needs to be paranoid about sea-cocks- but you DO need to look at equipment regularly to be aware of problems before they bite you...
If you open and close them regularly - you are less likely to find one frozen in the wrong position!

Graeme

 

[Searush]

I am of the "never close the seacocks" school - I would simply not remember to open them again, leading to disaster & recriminations.

My first boat only had cocks on the cockpit drains - there were no other holes in the hull (engine was o/b) and she had the driest, dustiest bilges in the world. Current boat has cocks for engine, sink, seawater tap, toilet & cockpit drains plus a hole in the stern for the prop shaft. She always carries a gallon or two of bilge water, but most comes over the side I reckon, with a slow drip from the prop unless just greased. She dries on every tide and has done for over 20 years in my ownership and never had a cooling water problem.

Leave 'em open, the risk of failure is low, even if the consequence is fairly severe. Leave 'em shut & the risk of forgetting to open them is quite high - especially if you are on your own - and the consequences are probably as expensive as sinking. That's my risk assessment anyway.

 

[stav]

My old girl is on a drying mooring in a harbour so sheltered. I leave the sink, bilge pump, cockpit drains and engine seacocks open. The heads and head sink are closed, very easy to access. The toilet bowl is just below the waterline and with young children on board the little waterin/waterout lever can be played with and the washbasin seacock only has space for one jubilee clip.

When I have kept boats on exposed swinging moorings in Portland Harbour I closed all seacocks then on the basis she could sink before anyone else notices and when it was rough the boat could get thrown around a bit.

Good luck with it but hey 2 minutes work in reality and better to agree a practice and stick to it. How about a comprimise of a second inline valve with easy access to keep the water in the engine. Second thoughts that is a pants idea. But will leave it there for others to laugh at.