Seacock Issues
From a recent project addressing many of the issues with poor quality seacocks, I am please to endorse a new type of Seacock which I have been involved in the development of
Gate Valves
These are typically found on older crafts. They generally are the least suited to marine applications. There is no way of telling visually if they are open or closed. Faults found are usually failure of the handles. Note if the handles spin too easily then they are probably not operating the gate. The gate seizes and forces the thread on the handle. Further they have a habit of leaking due to the gate not closing fully from marine growth or limescale on heads outlets. Many of these valves are made from brass not bronze or DZR (De-zincification Resistant Brass) Unless the gate valves are particularly good quality which is rare but can be found on larger valves that are made from all bronze including the handles on small craft, the advise is often to replace. They should never be replaced for another gate valve.
Cone Valves
SeaSeal Seacocks
SeaSeal are high-quality, forged Dezincification Resistant (DZR) brass marine valves designed to control water intake/discharge below the waterline. Made in England, they are engineered for durability, corrosion resistance, and user-serviceability, allowing them to be freed or maintained while the boat is still in the waThey are our recommended replacement seacocks, more information can be on this website: www.seaseal.co.uk
Blakes
Older type made by ‘Blakes’. The older valves are made from bronze whilst newer ones are DZR. Typical faults found are the lack of maintenance and seizure of the outlet on heads and deterioration of the hull bolts. Worn valves leak. The valves need to dismantled and greased yearly.
Ball Valves
The quality of these vary greatly. Many cheap ones are made of nickel coated brass and have mild steel handles which rust. The quality of the nickel coated brass bodies can be questionable and unsuitable for marine use. However they are the most commonly found seacocks on craft and benefit from being easy to use and identify whether they are open or closed.
When replacing these seacocks, the material should be bronze or DZR brass, (marked CR on the body of the seacock). Avoid seacocks marked CW617N, these are high zinc content brass suitable for fresh water domestic purposes.
Plastic Seacocks: Forespar, Trudesign & RANDEX
‘Plastic’ seacocks.
Forespar uses proprietary material called Marelon®, which is a carbon fiber and glass-reinforced polymer. Forespar make skin fittings too.
Trudesign use a glass fiber reinforced polymer for the seacocks and fittings
RANDEX use a glass fiber reinforced polypropylene (typically found on Beneteau holding tank outlets)
Plunger type: Elanco
Elanco seacocks, specifically known as Elanco Hull Seals, are specialized, flush-mounted seacock valves developed in the 1970s, designed to reduce drag and turbulence for sailing yachts. Commonly fitted on Hustler, UFO, and early Oyster yachts, these bronze or aluminum valves operate as a secure,, tapered plug mechanism, with parts and servicing still available through Landamores.
Skin Fittings, Hose-tail Fittings
The material should be bronze or DZR suitable for marine use, alternatively appropriate marine grade plastic to be used with their associated seacocks. Test bronze/DZR by scraping to see if they have dezincification (pinking or taking on a dark red hue).
General Advice
All seacocks should be easy and positive to operate. They should show no sign of corrosion, the tailpipes should show no signs of dezicification. They can be tested if they open and close correctly whilst out of the water by pouring water through the pipe whilst the craft is out of the water. If the material of the seacocks is unknown (no mandatory marking scheme) they should be regulary inspected. The hosetails should be the right outside diameter for the inside diameter of the pipe. The worm drive (jubilee) clips should be all 316 stainless. Backing pads should not be solid wood but ideally be GRP (buy from www.seaseal.co.uk or at least marine grade ply.