TESTING A GROCO SEACOCK

[bornfreee]

A very good quality seacock.
http://m.youtube.com/watch?v=KKTKQUcvU9w

[Miker]

An interesting test, however, when is a saecock, or a hull put at that kind of stress? As in, having the saecock pulled sideways from inside? I'm not an engineer, but I don't see it's as relevant as putting the saecock in a panel, and pressing from outside to see whether it pushes through the panel.......... Or have I missed something?

[storm petrel]

Most likely way a seacock fails underway is when it is bumped or forced. Could be a boot, an anchor or someone applying a ridiculous amount of force to open it (ie if it was seized). So I think the side force test is relevant.

[bornfreee]

I agree Mark that is why they quote 500 pounds

[Troppo]

A bloke I know with a 30 foot ancient riverboat, ply on hardwood framing, had a bit of a weep of moisture around a seacock [actually a valve on a thru-hull so not specifically a seacock by definition]. He pointed it out to another bloke with him and this guy reached down to grab it and shake it to see if it was loose. The first bloke managed to stop him from touching it. A week later on the slip when they went to remove the thru-hull, it fell out in their hands. The wood around the thru-hull had rotted and they were white-faced contemplating what would have happened if they had tried to wriggle it when out on the water.

My story has nothing to do with the Groco seacock test but I think it highlights that any hole in the hull can have serious consequences and so a bit of care with equipment [and installation and maintenance] is beneficial.

Nobody purposefully goes and kicks a seacock in their boat or throws a battery at it but accidents happen and it would be nice to have assurance that the fitting is tough. While a serious knock on the inside would be rare, the consequences of failure of a thru-fitting is totally serious. You would think that all underwater fittings would be tough seeing as they are so important but that is not the case, some manufacturers seem more interested in making money than a quality product. At least with independent testing and a 'standard' set by the boat association or whoever then a certain level of toughness is more assured.

troppo

[steve]

Troppo,

The guy who tested the Groco seacock also tested several other seacocks including three types of Marelon valves and some arrangements of bronze valves. He presents them here:-
http://forums.sbo.sailboatowners.com/sh ... p?t=136999

The tests videos, and the discussion forum which follow them, are very informative.

One of the tests was on a Marelon through-hull with Marelon ball valve, which looks like the arrangement you have just installed. Unfortunately it came out of the test badly.

Also tested was a bronze through-hull with a bronze valve which seems to be the most common arrangement in Australia. It performed better, but still failed before reaching the target test force of 500 lb. The failure was breakage of the through-hull tube, not slippage at the mismatched thread mentioned elsewhere.

I think the lesson I have learnt from these tests and other recent posts is that, unless you are prepared to go to the expense of installing flanged seacocks (bronze or Marelon), make sure your seacocks are located within small compartments where there is no possibility of heavy objects being stored and no possibility of a foot ever coming in contact with them.

Steve