PBO Seacocks cock-up

[rex_seadog]

Just received my June PBO and must take issue with the comment that Blakes' seacocks turn off with a 'quarter turn'. They most certainly do not as I've commented several times on this forum and only realised last year after suffering many years of wet bilges, lockers etc. Assuming you start with the handle opposite (i.e. at 180 degrees) to the outlet pipe) then you need to turn about 110 degrees to completely turn off. In practice we push it as far as it will go against the pipe. Once it is dismantled it is obvious why this is so. Sorry to keep repeating this advice but I want to share my delight of a dry boat with anyone who is similarly suffering.

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[chriscallender]

Hi Rex,

Good information to know, since I think I am therefore leaving mine not fully off ... so I might as well have just left it in the on position when I left the boat for the last year or 2 since the boat will still sink if the hose fails!

However, one thing puzzles me ... why would the seacock leak to the bilges if it was left partly on, any more than it would leak if it were fully on or fully off?

Chris

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[Birdseye]

depends what they are connected to. I made the same discovery - my leaks were seacocks connected to henderson bilge pumps, and in a chop some water fed back through the one way valves of the pumps.

<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[anabel]

If seacocks properly installed & maintained there will be no leaks no matter what the sea conditions or the position of the seacock handle. From fully open to fully closed requires an 180 deg. turn of the handle. I have the handle such that when seacock is fully open, one of the nuts is fully exposed. This one I have painted red. Then when fully closed this nut is hidden by the handle. This means I only need to glance at the sea sea cocks to know whether it is open or closed. This applies to both inlet & outlet. Each lay up season I take both asunder & clean & grease same. I would always have the bowl pumped dry when heading out. Otherwise water in bowl can be splased out in rough conditions.
Rgds.
EH.

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[ashanta]

The sea cocks with lever action on my boat (3 of them) operate on a quarter turn. The two seacocks for my cockpit drains are gate valves.

Regards.

Peter.

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[brianhumber]

Re: Blakes Seacocks?

Don't understand you here,
If you have a simple one pipe seacock, when the elongated oval port cut in the taper plug is in line with the pipe then fluids can pass from pipe into plug and thus out to sea (or vice versa)
When the taper is turned sufficiently such that the enlongated port is no longer in line with the pipe aperture but facing the brass body of the cock then fluids can no longer flow. To make sure this has happened people normally turn 90 degrees

If you are having leakage then it is possible the taper is erroded either side of the port. This is beginning to happen to mine on the toilet discharge tapers due to the corrosive element of sewage and urine after insufficent pumping through but they are 16 years old now so I am not complaining. The inlet tapers are as a virgin.

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[rex_seadog]

Re: Blakes Seacocks?

<When the taper is turned sufficiently such that the enlongated port is no longer in line with the pipe aperture but facing the brass body of the cock then fluids can no longer flow. >

It's exactly as you say, brianhumber, but to achieve the situation where there is no overlap between the oval cutout in the cone and the outlet hole you need more than a quarter turn. It all depends on the relative sizes (angles subtended by the arcs) of the respective holes. It's quite obvious if you dismantle the valve.

To answer chriscallender, in our case the loops on the inlet/outlet pipes of the heads are such that when we are well heeled to starboard they are below the water-line and if the valves were slightly open as described water would back up into the bowl and slop over. As we have only shallow bilges this would find its way into every corner of the boat. We had very little leakage from the actual body of the valve and this only because I over-tightened the bolts in a futile attempt to prevent the water backing up into the loo. All this did was to squeeze out the grease and make the situation worse. According to Blakes you should be able to move the levers with the pressure of only two fingers. It was only after I had removed the valves with the intention of replacing them that I realised the geometry was such that the extra 10-20 degree turn was required.

By the way, our Blakes valves are the older versions without the grease nipple but as far as I know they are otherwise identical.

To Anabel, not sure we are talking of the same valves as on mine it is imposible to turn 180 degrees from the fully on position as the handle comes up against the outlet pipe after, I guess, 150 degrees. Sorry if I'm being pedantic but in this case size (number of degrees) matters.

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