seacocks - gatevalves vs ballvalves?

There are a couple of problems with gate valves that make them less suitable for boats than ball valves:
1. They are usually made of brass which isn't sufficiently corrosion resistant for a marine environment.
2. They don't have the positive on-off action which a lever gives you; they use a threaded rod to screw down the gate and it isn't immediately clear if the valve is fully closed or has met some obstruction on the way.
3. They don't usually have flanged bodies that can be through bolted to the hull. They have to be mounted on a skin fitting which is a less secure installation.

I'd go for bronze or stainless or, my real preference, Xytel ball valves.
 
Re: sea cocks - gate valves v ball valves?

Well trod path. Gate valves are no - nos, particularly below the waterline for the reason Saltyjohn says. Bronze gate valves or even better Blakes cone type seacocks are the way to go. Not a lot in it in price, but space may determine one or the other.
 
[ QUOTE ]
For me gatevalves are more reliable in the long run. Which ever way you go, don't cut the quality.

[/ QUOTE ]I am not sure how you believe that gate valves are more reliable. There are a large number of gate valves on boats which have poor quality innards and in which the knob turns round and round and does nothing.

The link to the Australian hull valve page is interesting, however I note that there aren't any gate valves in the pages I looked at either.

My suggestion is either good quality ball valves (you know whether they are open or closed...) or Blakes type cone valves if you can afford them!
 
Re: sea cocks - gate valves v ball valves?

You are right.

100 lines. Never fit gate valves to a boat!
 
Re: sea cocks - gate valves v ball valves?

I have to agree with all of the above, although my boat has gate valves on soome throught ulls, but they are all above the waterline. Being changed out as they get old!
 
Re: sea cocks - gate valves v ball valves?

Blakes valves are the way to go. You can service them afloat ( as long as you haven't allowed them to sieze).
You can remove the taper in order to poke the skin-fitting strainer, afloat, stemming the flow with a rag or taper.
Every fitting should be a blakes - especially now the modern ones have grease nipples. (now I need to find a LOT of cash to follow my own advice)
 
Re: sea cocks - gate valves v ball valves?

When I replaced my toilet outlet last year, the proper Blakes was only £20 or so more expensive than a bronze ball valve, including the through hull and tail. Crunch was that there was not enough height to get the ball valve in anyway - and my grandchildren will appreciate my choice!
 
Re: sea cocks - gate valves v ball valves?

Sorry Folks,

In the 1970's and 80,s most uk boats were fitted with gate
valves. The advantage of the gate valve is that it can be maintained. If every winter the gate is removed, greased and replaced then this should last for years.
In my previous life I skippered a sail training vessel with 13 gate valves. Once a month each gate valve was closed and reopened to clear the thread. When the gate valve is fully open, then turn it back half a turn and it will not seize.
In my present boat I am changing the ball valves to bronze gate valves because I can MAINTAIN them. All it needs is a little EFFORT!!!!!!
 
Re: sea cocks - gate valves v ball valves?

Part of my reason for asking was the failure of a gate valve, located below waterline for a cockpit and scuppers (combined) drain. The valve stem broke in closed position. Had closed it to change a hose which had holed. That was at start of the summer, so had to take the boat out of the water to change the valve (for a ballvalve).
Now intend changing the others this winter.

Thanks for all comments.
 
I am totally against gate valves because crustacean/barnacles can quickly jam them so that they do not close completely. Unfortunately it is very difficult to tell that they are not closed, whereas with a high quality ball valve, it is obvious.

However, be very wary of cheap ball valves that are supposedly marine bronze. Apparently china has been churning out some rip of ones made from very inferior brass, and with the ball made of mild steel with chrome. They should last about 6 months in sea water!
 
Re: sea cocks - gate valves v ball valves?

I've got 2 gate valves on my boat. I've been thinking for some time of replacing them with ball valve types - but I'm now wondering whether that's a good idea. At least with the gate valves I can strip them right down to their working parts for examination and greasing - so I know what condition they are in. I do this once a year when the boat is ashore for the winter.

If you don't maintain gate valves at all they'll fail.
 
Re: sea cocks - gate valves v ball valves?

i once had a gate valve fall apart on me the inside had coroded. good job the boat was out the water might not be here to tell the tale other wise. always fit good quality ball valves or if you can afford it proper cone sea cocks!!!!
 
With a ball valve, when open, there is no restriction to the through flow of water. The closing mechanism (i.e. the ball) is tucked away out of sight and misses all the gunge. When it is closed, there are no cavities for nasties to grow.

No contest!

It is also easy to add a switch if you wish to show valve state as a finally check when leaving the boat. Try that with a gate valve!
 
You must log in or register to reply here.

Other threads that may be of interest

Sea Change
Mini sandblaster for rust spots on keel?
2 3 4
Replies
63
Views
2K
Mister E
M

Share this page

Top