The title says it all! Simply threading a ball valve, or in-line valve as pictured above, onto a thru-hull (top photo on this page) is not a proper seacock. Sure, many sailors refer to any thru-hull mounted valve as a seacock but in the proper sense threading a ball valve onto a thru-hull or mushroom head is not a "proper" seacock.


This ball valve shows what can happen, in less than a year, using cheap "yellow brass" valves purchased from Home Depot. This valve was literally a week or two away from catastrophic failure of the boat sinking type!


As I've said, and will continue to say, USE ONLY marine rated valves of either bronze, stainless steel or Marelon and DO NOT buy valves for your boat at hardware stores or home centers like Home Depot!