Lavac sea cocks

[suse]

Should BOTH inlet and outlet seacocks be open when using the Lavac? At the moment, the inlet (narrow pipe) is open (but can be closed when required), but the outlet (large dia pipe next to the foot of the pedestal, with very big seacock) is CLOSED, and stuck shut at that.

I can flush with lid down and achieve a vacuum, then wait a few seconds, then pump again. However, on second pumping, I get some seepage back into the bowl. But most must get pumped out - I dont get back everything I started with. Sorry about this - cant think of a better way to put it.

I presume, nevertheless, that I should have both seacocks open, even though it appears to be working fairly well with just one (inlet) open. I'm just a bit worried about WD40-ing the outlet seacock and forcing it open, as it's below the waterline, and I dont want water coming into the boat where it's not wanted.

 

[Twister_Ken]

Both open - seawater comes in through one and 'seawater plus' exits through other.

Don't know where your seawater plus is going at the moment, a mystery!

When leaving the boat you can pump with the inlet closed (or the lid up) to empty the bowl, then close the outlet to prevent any back flow.

What sort of valve do you have on the exit side?

 

[summerwind]

I am amazed that you can get a vacuum. I suspect that what is happening is that you pressure up the whole system when pumping the handle and because the debris can't get out of the exhaust pipe, it is going out of the inlet. When you stop pumping, water is coming back in until the anti-syphon hole breaks the syphon. I think I would take some quick action to dry out and fix your sea cock!

What sort of sea cock is it?

 

[suse]

Not at all sure about what kind of valve, I'm afraid.

 

[suse]

Non- technical reply - the seacocks are those with a handle - inline = open, across the pipe = closed.

Is there any way to free the seacock without drying out? This would be very awkward at the moment.

Bring back the bucket, I say. Had this on a previous boat, and it never stuck, or refilled itself.

 

[Twister_Ken]

I asked because if it is a Blakes (see www.blakes-lavac-taylors.co.uk/blakes_seacocks.htm to check) you can often free them up by backing off a turn or two on the bolts that hold the keeper plate (just below the handle).

 

[suse]

Thanks, Ken - I just rang Blakes and spoke to a really good chap, and with a photo of the seacock in front of me, I now understand what you and he were talking about.

PS I've got a selection of tapered wooden plugs, which will give me some peace of mind - maybe!

PPS Just reread this - tapered wooden plugs for seacocks, of course!

 

[ccscott49]

The oulet seacock must be open, or the water wouldn't go out, when you close the lid, the pump sucks the stuff out the outlet and lets water in the inlet to flush the toilet, I think, so the outlet must be open! I'd check the seacock again, and for sure free it off so it can be opened or closed, for safetys' sake. Agter you have done that, then we can see whats what.

 

[suse]

I suspect Summerwind is probably right about everything going in and out (ish) of the inlet pipe, because the handle of the outlet pipe is at a very stuck right angle to the line of the pipe.

 

[ccscott49]

But did the toilet work at anytime? and the handle canm be removed and fitted in the wrong place, mine can, anyway, repair the seacock first, as has been siad, you just loosenn the screws a little and then get a larger lever on the sea cock, this will move it.

 

[summerwind]

As the others have said, loosening off the screws on the top of the sea cock may well allow you to move it. Before you break off the handle with a long lever, as I once did, it might be an idea to tap - I said tap - around the body of the sea cock.

It seals because two tapered polished surfaces are held in close contact by the downward pressure of the friction plate. A little tapping around the body of the sea cock, once you've backed off the screws (NOT removed them) will loosen it up a bit. A touch of heat might help as well, as long as you don't melt the outlet hose;-)

Be warned - the previous owner may have screwed the plate down really tight because the cock was leaking. You may well loosen it up but allow it to leak again. The latest pattern of Blakes sea cocks have a grease nipple to allow lubrication of the moving parts and help with sealing. As you've probably got the older type, getting it apart and cleaning it is probably a high priority.

 

[ccscott49]

Quite right about the new seacocks having a grease nipple, but you can modify yours, when you strip them down, just drill a 21/64" hole in the side, in a thick part of the body, and tap 1/*2 BSP, you can then screw in a grease nipple. If the grease nipple goes in to far and jams the taper, just put a suitable stainless washer under it. I modified mine this way, due to the seizure problem.

 

[MedMan]

There's lots of good advice amongst the answers you have received so there is little I can add other than to emphasise the serious risk of doing anything too brutal whilst still afloat. Blakes seacocks are subject to corrosion as well as seisure - I have just replaced my lavac outlet for the second time in 25 years. Slacking off the two machine screws holding down the clamping plate and waggling the handle back and forth should be reasonably safe, but anything involving long levers or blowlamps I would only contemplate when dried out or ashore.

Good luck!

 

[peterb]

Be very careful about releasing the outlet pipe. If you have been pumping with no way out then this pipe will be pressurized. If you release it then the "seawater plus" can be squirted in all directions (or, from personal experience, mainly in your direction). Before you do anything that might release the pipe, leave the system for 24 hours so that the pressurized contents can seep away.

 

[halcyon]

Does anyone know why we use this type of valve, why not a ball valve ?

These are not subject to seizing up, and have full flow.

Brian

 

[MedMan]

I would guess that decent ballvalves are relatively recent and that the Blakes type were the best available at the time the Lavac was designed. I could be entirely wrong though. A month or so ago sailing in the Ionian I met a retired engineer who used to work for Blakes. If I see him again in the Autumn I'll ask him!

 

[Twister_Ken]

Surely it couldn't be becasue the company that manufacturers Lavacs also makes Blakes seacocks?

That would be too much of a coincidence.

 

[halcyon]

A lot seam to have this sea cock, but could see no reason.

Have to fit new toilet and valves, ball valves are £4.17 and £11.69 + vat, blakes type £73 and £90, seams to good !!!

Only thing I can see is that we need a skin fitting and elbow with the ball vave.


Brian

 

[ccscott49]

Blakes seacocks are also full flow, are very efficient, do not seize (if you operate them once a week) are easy to service, I've never had one corrode, being made of bronze and I have 12 on board, never had a minutes trouble with them. BUT they need to be operated and kept serviced and greased, like I said I modified my old type to take grease nipples, then I grease them and operate them at least once a month, (offshore working the rest of the time) You may have guessed, I like them!

 

[dickh]

Blakes type seacocks were the only ones available up to a few years ago and as others have said, if serviced and greased on a yearly basis give very little trouble and are reliable. Ball valves are a recent product(my boat has them) and are perfectly OK as long as you get BRONZE ones - there are a lot of cheap BRASS ones on the market. The only trouble with ball valves is they usually come with a painted steel handle which very quickly gets corroded in the bilges and snaps off...(as I know, then you have to fit a new ball valve... - one fitted 2 years ago is getting quite stiff already...)
Also ball valves, by the time you have fitted them to an outlet and then fitted a hose fitting, end up quite tall and vulnerable from knocks etc.
You could also investigate the plastic MARANOL? type which are from the US and apparently are OK - but I don't have any experience of them - but are approved fittings.

dickh
I'd rather be sailing...