Seacocks at the Soton Boatshow

[Guest]

Having looked over around 10 different makes of boat at the show, I noticed that all used the red levered ball type of seacocks.

I really need to replace four on my boat - all are the Blakes type. Blakes now cost about £85 a go compared to about £15 for the ball type.

I would like to go for the ball type but what are the drawbacks ?

Also, no boats at the show used wood mountings on the seacocks , only sealant it seemed to me. Is this ok now ?

Many Thanks

 

[Guest]

Vic, I have used both types and theres really no difference, but I must admit to prefering the lever type. Quick both to operate and see if its open or closed. Some people here may disagree but I actually think they are less bothersome to maintain.If they are operated on a regular basis they are less prone to siezing. As for fitting directly to the hull without wooden backers, again no problem.

 

[Guest]

I lack the engineering expertise to provide a reasoned answer, but I suspect there are several disadvantages against the cheaper valve. I hope one of our website experts sees your posting, as at the back of my mind are contrary thoughts. Many of the ball valves may have been designed for domestic plumbing (ie non-marine materials)and may not be suitable. Although a reputable chandler would hardly supply them?? I will now have to fork out £85 x four. Gulp!
I used wooden backing pads when installing sea cocks, but I grew up regarding Hiscocks Cruising books as The Sailors Bible. Perhaps materials and methods have moved on, but it stills seems like a good seaman-like procedure.

 

[Avocet]

I've wondered about that too. I have both on my boat but have not dared to use the ball type below the water line before this season - when I replaced my engine raw water inlet seacock. I think one problem might be that the cheaper ball valves will have a number of different metals in electrical contact with each other. This might well lead to failure one day. The traditional ones seem to last forever and can be completely stripped and greased and tightened up when they start to leak - but at the price they are, I could throw away the ball valves every few seasons and still be quids in! If there's one thing I don't like about some some ball valves, it's that they don't have a big, wide flange to mount through the hull. Mine is just screwed on to a skin fitting. This makes them more vulnerable to snapping off if tripped over or if something heavy in a locker were to fall on them.

As far as backing pads go, I think the intention is to use the wood as some sort of gasket between the seacock and the hull in the hope that when the flange bolts are tightened, they're all taking a similar load. Depending on how smooth and flat the inside of your hull is, you might find a small lump of GRP putting big loads into the seacock flange without the wood, whereas with it, the lump would just make a dent in the bottom of the wood. I suppose there's also the advantage that wood will swell if wet so the self-sealing characteristics would be improved. Finally, I also suspect that before the technology existed to manufacture ball valves and high tech polyurethane adhesive/sealants like Sikkaflex, traditional seacocks were all we had!

If I need to repalce any more, I'll probably use ball valves and will check them regularly. I'll do my best to screw them on to the shortest skin fitting I can and I'll try to make as certain as I can that the skin fitting and valve body are made of the same material. Finally, I probably won't use a wooden backing pad because the clamping area of a skin fitting locknut is so small. I will, however, bed it in with copious amounts of Sikkaflex.

...and when my boat gets surveyed again in four years time, I'll probably have to rip it all out because I bet some surveyor will come up with some reason why I can't!

 

[roger]

The seacock problem is mostly to do with electrolytic corrosion and the right metals. From what I've heard, some sorts of bronze are little more than brass and will dissolve quite quickly in sea water. I'm sure other contributors are much more informed on this topic than I am.

 

[johnt]

just to reassure you Avocet...Ive had the same ball valve on my raw water intake for about 12 years no problems whatsoever! just a twiddle now and then to make sure it still works

but the blake 's valves on the other outlets freeze up if they dont get serviced!

one plus point ....if your quick you can change a ball valve WITHOUT taking the boat out of the water, but you do have to pump the bilges afterwards lol (it was the galley sink sea cock)

 

[dick_james]

If you get a peep at the specs for ball valves you will find they are supposed to be good against all sorts of nasty toxic substances, including salt water. They are used extensively in industry for these reasons (in fact, that's why they were developed) Generally from single material (chromed brass or stainless) apart from seals which are usually PTFE. You can get servicing kits for the better ones. I've had them on my boat for several years now, no probs. Go for it!
Dick James