Seacocks (gate valves) and advice request

[FairweatherDave]

I have uploaded several piks to a picasa album as attempts to upload here here have been painful. Click on the pik to get a decent size image

https://picasaweb.google.com/DWMacAdam/CentaurSeacocks?authkey=Gv1sRgCMSL2rXS6uTd8wE

Been putting this job off but it has to be done. I know the gate valves have to go but what are the chances of being able to disconnect them from the skin fittings? My boat is a Centaur and I would presume the skin fittings should be okay (inevitably I will examine them). Polite reactions to the state of the gate valves are welcome along with other advice! If anyone can advise suitable size of the new seacocks even better

I won't be changing the blakes seacocks.
Thanks Dave

 

[VicS]

What is wrong with the existing gate valves?

A little surface pink colour on the outside is nothing.



I'm surprised they are not bronze if original.


You'll replace with ball valves if you do need to replace presumably.

The cockpit drains are 1". I can see the size marked on one!

Id guess the galley drain may only be 1/2" (perhaps 3/4")

 

[Scarboroughsloop]

It also looks like one valve only has 1 hoseclip on it ans on others the second clip does not seem to be over the valve anyway so is probably doing more harm than good.

 

[vyv_cox]

I agree with VicS. Why change them? The weak point of this type of valve is the very small section at the end of the actuating rod, that drives the gate itself. This commonly breaks due to dezincification, so the gate will close but cannot be withdrawn. I would remove the gate mechanism by unscrewing the bonnet, leaving the body in place. Inspect the internals and if all looks well, replace them.

Personally, I see no point in cockpit drain cocks anyway, unless the cockpit floods under engine. If you close them when the boat is left the cockpit will flood with rain water. Just leave them open but exercise them occasionally to keep them free of fouling.

 

[testmonkey]

If this was my boat I'd change all those gate valves to new bronze or DZR ball valves. Blakes valve I would clean and rebuild if necessary. Whilst at it I would also consider replacing all hoses and clips as well, making sure to double clip all hoses and tape a suitable size soft wood plug next to the valve. But each to his own, personal taste varies. I've had a engine intake hose burst on me and then have to deal with a broken gate valve and after that experience take no chances...

 

[awol]

Personally, I see no point in cockpit drain cocks anyway, unless the cockpit floods under engine. If you close them when the boat is left the cockpit will flood with rain water. Just leave them open but exercise them occasionally to keep them free of fouling.

Apologies for the digression - my cockpit drains get closed when it's party time, otherwise those in the cockpit get wet feet. I reckon they are a social essential just like nibbles and limes for the gin.

 

[FairweatherDave]

Thanks for the replies. Not changing them is music to my ears as I can't see anything wrong with them, except the various deposits in the pictures are not pretty.... I don't close the the cockpit drains as I follow Vyv's view about rain, and I do "exersise" them periodically, and have tugged the fittings etc to test for structural strength. I have replaced the water inlet pipe to the engine and I do know exactly where my bungs are. Gate valves are out of favour though and I understand why but I like the if it ain't broke (and I keep them serviced) no need to change..... I would do the job if/when I need to re-engine the boat.

 

[prv]

Personally, I see no point in cockpit drain cocks anyway

You would if you'd seen the state of the hoses when we bought KS

Personally I'd prefer GRP tubes stoutly glassed into the hull, though. No valves needed then.

Pete

 

[ghostlymoron]

I agree with VicS. Why change them? The weak point of this type of valve is the very small section at the end of the actuating rod, that drives the gate itself. This commonly breaks due to dezincification, so the gate will close but cannot be withdrawn. I would remove the gate mechanism by unscrewing the bonnet, leaving the body in place. Inspect the internals and if all looks well, replace them.

Personally, I see no point in cockpit drain cocks anyway, unless the cockpit floods under engine. If you close them when the boat is left the cockpit will flood with rain water. Just leave them open but exercise them occasionally to keep them free of fouling.

The usual reasons for getting rid of gate valves are that :-
1. You can't tell at a glance whether they're open or closed
2. They can get a foreign body stuck in the gate and appear to be closed when they are in fact partially open
3. The operating spindle/mechanism can corrode (but this can happen with ball valves as well)
The OPs valves look to be of substantial construction and have certainly stood the test of time. However, for reasons 1 and 2, I would replace them with DZR ball valves and in future exercise them frequently to make sure they don't seize up.

 

[johnlilley]

Gate valves will often fail internally where they obviously cannot be seen. The best test for identifying this failure before it occurs is to fully close the valve quite tightly and fully open the valve quite tightly, perhaps slightly more tightly than you would normally undertake.

When you start to reverse the movement from tight open or tight closed, on a good valve there should be very little free movement on the handle before the gate starts to move. If you note that you are getting a considerable amount of free movement before the gate obviously starts to move then this is the suggestion that the square cut threads on the spindle thread connecting to the gate are noticeably worn. in some cases you will find that just the effort of tightening the valve that degree extra is the last straw for the spindle and the handle will suddenly spin freely.

Eventually what happens is that these threads crumble and break just leaving the handle of spinning round with basically a stripped thread in the gate. This can be very inconvenient if the valve is in the fully closed or fully open position. Obviously, take care when doing this if the vessel is afloat. It is quite surprising how many gate valves will fail on this test as, it is often the spindle that is of the low quality material.

f the valve has to be removed and you want to minimize the risk of the skin fitting turning at the same time then if access will allow you can put a saw cut down the side of the valve where it is screwed on to the skin fitting. Obviously take care not to cut into the skin fitting and this does make the valve easier to remove and minimises the risk of the skin fitting turning.



John Lilley

 

[aquaplane]

On my Centaur I replaced the cockpit drains and the galley seacocks when I bought the boat.

The heads ones are Blakes like yours so I just serviced those and kept them.

The engine inlet has an integral strainer so I kept that too, it looked OK when I stripped it down so I was happy with that.

I couldn't get the hoses off the cockpit drains but found that, with the clips off, I could unscrew the hose adaptors with the hoses still on. It was then easier than I thought it would be to get the valves off. I had stilsons on the 90° elbow to hold it steady and a large adjustable on the valve to turn it. About 18" tools IIRC, much bigger wouldn't fit in the locker.
There was some plumbers paste type stuff on what I took off but I just put thread tape on the new ones.

I excersise the cockpit drain valves every time I go in the locker open the engine coolant seacock.

 

[FairweatherDave]

Thanks for all the further replies. Really really useful stuff. Funny how you can read up so much around the subject yet putting up a specific post with piks takes my confidence up so much more. . Thanks Dave

 

[rob2]

I'd like to add another voice in favour of keeping them -- but... Externally they look to be in good condition, but if you're out of the water at present, I'd second the advice to unscrew the actuator to check internal condition and to grease the threads. If everything is good inside then they're keepers!

It's just as likely that any failures will be the hoses and clips so take the opportunity to examind them. Flex them in your hand and if they are starting to feel brittle, then it's time to replace them. A rubber factor will be able to supply the hose at a greatly reduced price compared with buying from the local chandlery. In my case, living in Basingstoke and the boat on the Hamble, I can use factors in either Southampton or Reading. When inspecting the hoses, have a look at the worm gear in the clips, even some stainless clips have rusty gears which could let go, unseen.

Rob.

 

[VicS]

On my Centaur I replaced the cockpit drains and the galley seacocks when I bought the boat.

The heads ones are Blakes like yours so I just serviced those and kept them.

The engine inlet has an integral strainer so I kept that too, it looked OK when I stripped it down so I was happy with that.

I couldn't get the hoses off the cockpit drains but found that, with the clips off, I could unscrew the hose adaptors with the hoses still on. It was then easier than I thought it would be to get the valves off. I had stilsons on the 90° elbow to hold it steady and a large adjustable on the valve to turn it. About 18" tools IIRC, much bigger wouldn't fit in the locker.
There was some plumbers paste type stuff on what I took off but I just put thread tape on the new ones.

I excersise the cockpit drain valves every time I go in the locker open the engine coolant seacock.

Keep an eye on the strainer basket. Our experience was that it was ordinary brass, dezincified and fell to bits one day when we tightened the cover down while the basket was not quite positioned correctly

 

[aquaplane]

Keep an eye on the strainer basket. Our experience was that it was ordinary brass, dezincified and fell to bits one day when we tightened the cover down while the basket was not quite positioned correctly

Mine looks OK for now. It can be difficult to align the strainer though, I fit the strainer to the lid and then screw it in in one piece.
If I put the strainer in the housing it always falls over and won't engage in the recess in the lid.