Sea cocks

[Johnny WAFI]

Hi all

What is the life expectancy of the original seacocks in a Sadler 29? Should I be doing something?

 

[Tranona]

If they are Blakes then just do the regular maintenance. If ball valves then they are likely to be bronze if original. If gate valves get rid of them and replace with DZR or composite.

 

[rogerthebodger]

If they are Blakes then just do the regular maintenance. If ball valves then they are likely to be bronze if original. If gate valves get rid of them and replace with DZR or composite.

Tranona

What is your view on 316 stainless steel ball valves as a seacock

I fitted 3 part stainless steel ball valves for ease of servicing

 

[Kwik Decision]

Hi all

What is the life expectancy of the original seacocks in a Sadler 29? Should I be doing something?

If they are like ours were, most will be blakes. Service once a year when out of the water (lots of instructions on line), and they will last as long as the boat. The exception may be the engine seawater inlet - ours was a 1/2" ball valve, which was replaced with 3/4" DZR skin fitting / ball valve / hose tail when we re-engined. As you are looking to replace your Bukh, you may well need to do the same...

 

[johnalison]

The seacock in the heads will certainly be Blake’s, but I recall that the others on ours were gate valve affairs, which should be replaced in any case.

 

[Tranona]

Tranona

What is your view on 316 stainless steel ball valves as a seacock

I fitted 3 part stainless steel ball valves for ease of servicing

Their biggest weakness is crevice corrosion on the threads. Underwater valves create perfect conditions for crevice corrosion of the threads of both valve bodies and fittings where oxygen starved water sits in the threads. Much the same with plain brass where galvanic action start the dezincification process. Failure of yellow metal seacock/valves is almost always in the threads of fittings, both through hulls and hose tails. Using bronze, DZR or composite avoids this.

 

[rogerthebodger]

Their biggest weakness is crevice corrosion on the threads. Underwater valves create perfect conditions for crevice corrosion of the threads of both valve bodies and fittings where oxygen starved water sits in the threads. Much the same with plain brass where galvanic action start the dezincification process. Failure of yellow metal seacock/valves is almost always in the threads of fittings, both through hulls and hose tails. Using bronze, DZR or composite avoids this.

What I did to try to prevent crevices corrosion is to use a Sikaflex type sealant in the threads to prevent any water ingress into the threads

No signs after 12 years of continuous submersion.

The same with my stainless steel prop shaft and my fabricated stainless steel propeller

 

[Tranona]

That is good advice. However yellow metal is dominant because of the range of valves and fittings available at modest cost and they re readily acceptable to the market. Maybe composites will achieve this kind of acceptance in the future as they have down under where there are no local yellow metal manufacturers. In Europe though yellow metal has such a wide market acceptance in different fields it will be difficult to shift.