Seacocks, types and materials of construction.

[aquaplane]

I'm new to seacocks, Aquaplane has no holes in her bottom.

Chiron has an interesting mix of Blakes ones and Gate valves. One of the gate valves on a cockpit drain was broken and the other is stiff, the engine inlet seems OK for now. I'm lead to believe that gate valves are the worst option, ball valves are better, Blakes say Blakes are the best.

I don't know that Blakes do anything other than brass so sticking with ball valves, is stainless essential, is brass "good enough" or will nickel plated brass do?

And the Blakes valves on the bog (which has been removed for lake use which may explain much) are stuck in whatever position they are in.

[Clyde_Wanderer]

My preference is S/S ball valves, the full bore/flow type if checked periodically are trouble free, plus you have the advantage of single action opperation, ensure they are at least 316 grade.
I changed the raw water inlet for s/s ball valve, the heads outlet is 1 1/2" but there is not enough room under the pan deck to fit a ball valve, so it is still utilising the bronze gate valve which I removed last winter stripped cleaned and greased and found it to be in perfect condition after some 20yrs in service.

[Silkie]

Underwater brass is a definite NON! Salt water is worse than fresh but brass contains zinc which leaches out electrolytically (is that a word?) and leaves the alloy honeycombed and weakened. IMO.

It may be that your first mention of brass is a typo since proper Blakes (and blakes-type) seacocks are made of proper bronze AFAIK.

[sahona]

Don't let the blakes out of your sight, they are the perros cohones.
A hammer and drift from the outside with the seal-bolts loosened will free them, grease and they're fixed.
Next best is the ball-valve IF ITS MADE OF THE RIGHT STUFF!!!! You don't want the handle to fall off as you try to close it... If you come across valves specified for use in the food industry - especially coffee- they'll outlast the standard ones.
Gatevalves - have to confess they do jam, probably because folks tighten up the shaft packing without lube, but I've never had a catasrophe with them.

[Fingal]

Ball valves are far safer than gate valves and come in a variety of materials. As suggested ordinary brass is not a great plan as it will eventually dezincify and become brittle. This is not an overnight process however. ASAP Supplies (google it) have a very wide range; DZR which is a brass with a low zinc content is generally regarded as perfectly safe to use for skin fittings. Blakes are possibly the best seacocks in the world but they are very expensive indeed.