See full version: Start Your Inspection with the Seacocks
Make sure any boat under consideration uses seacocks or ball valves that are UL Listed. Unapproved seacocks are a primary indicator that the boatbuilder is cutting corners, so they're the first thing a buyer should look at. And they're right in the bilge next to the stringers and frames, so it's easy to check both at the same time. here
Consumer Caveat: A few builders making low-priced boats don’t use seacocks or ball valves for through-hull fittings under the waterline. Some use non-UL-Listed ball valves. There is no government agency who inspects these things, so buyers have to do it, or they should hire a surveyor.
There can be confusion about seacocks vs. ball valves. True seacocks, used for generations, have a bronze body holding a tapered plug with a hole through it, held in place by a nut or some other easily removable means, and a handle. Turned one way, the plug lets water run through; turn the handle the other way, the flow is stopped. Servicing the seacock is easy: Remove the nut and the whole thing comes apart for cleaning or lubrication, which should be done yearly when the boat is hauled.
No Seal/No Dice. What's not fine are ball valves without the UL seal, made not for marine use but for some other purpose. They're almost as bad as gate valves, but not as easy to notice.
New boats built to NMMA certification standards have UL-Listed seacocks that are installed correctly with a backing plate against the hull to distribute the stress. When checking the seacocks, be sure they are UL-Listed for marine use. Sometimes, there's a plate with the UL seal, but sometimes it is on the handle. [links]
Rubber gets soft and deteriorates with time. Hose clamps corrode and break. The constant vibration of a boat loosens the soft hose on which clamps have broken and can easily slip off a seacock. Water gushes in.
Consumer Caveat: A few builders making low-priced boats don’t use seacocks or ball valves for through-hull fittings under the waterline. Some use non-UL-Listed ball valves. There is no government agency who inspects these things, so buyers have to do it, or they should hire a surveyor.
New boats built to NMMA certification standards have UL-Listed seacocks that are installed correctly with a backing plate against the hull to distribute the stress. When checking the seacocks, be sure they are UL-Listed for marine use. Sometimes, there's a plate with the UL seal, but sometimes it is on the handle.
The NMMA, following American Boat and Yacht Council (ABYC) rules, requires that the seacock withstand a 500-pound load applied to it for a period of 30 seconds – so if a crew member working in the engine room slips and fetches up on the seacock, it won't break off and let in a geyser of sea water.
There can be confusion about seacocks vs. ball valves. True seacocks, used for generations, have a bronze body holding a tapered plug with a hole through it, held in place by a nut or some other easily removable means, and a handle. Turned one way, the plug lets water run through; turn the handle the other way, the flow is stopped. Servicing the seacock is easy: Remove the nut and the whole thing comes apart for cleaning or lubrication, which should be done yearly when the boat is hauled.
UL-Listed seacocks are usually bronze, but some are made of a high-performance polymer like Marelon, too. Some builders prefer non-metallic through-hulls and seacocks because they're non-corrosive, but many prefer bronze. So long as they are UL Listed, either is approved.
The regulations also require a handle that swings through a 90-degree arc and clearly indicates whether the seacock is open or closed. Any boat that doesn't have proper seacocks is one to avoid.
Commonly known as DZR or CR brass, this alloy also comprises copper and zinc, but small proportions of tin and arsenic are added to resist de-zincification and to increase its physical strength.
When installing a through-hull fitting below the waterline of a solid GRP hull, it’s a good idea to smear some neat epoxy around the inside of the hole and let it cure before installing the fitting itself to ensure the laminate is fully sealed. If your hull is cored beneath the waterline (unusual, but not unheard of) it’s better to drill a smaller hole out first, remove the core material over an area twice the diameter of the fitting, refill the cavity and hole with solid GRP, and then drill out to the correct size for the fittings once totally cured. [links]
Regular brass is an alloy made from mixing copper and zinc and is often used in the manufacture of cheap marine fittings, including through-hulls. Although it might seem an ideal material for the job, it isn’t, as the zinc component can be dissolved out of the alloy through electrolytic or galvanic corrosion (de-zincification), leaving a highly copper-rich fitting that is very weak.
Also specially designed for marine applications, Alex-type seacocks, made by Italy’s Guidi, come with a bronze body and neoprene seals. Rather than having a lever, they sport a fire-resistant ABS operating knob and “plug” that retracts into it when opened. The advantage to using this approach is that unlike a lever arm-style seacock, the Alex valve can be mounted in areas where access is restricted. [links]
Question: I’m considering the purchase of a 60-year-old wooden powerboat that I’ve fallen in love with. I do have a question though. In the photo I sent in you can see the handle for the seacock used for the engine raw-water intake.
It is a bronze gate valve that the current owner says was in the boat when he bought it some 15 years ago. I’ve read that these are not compliant with current industry standards. Is that true and if so why? [links]
Gate valves can't provide a quick visual reference on whether a through-hull is open or shut. And the handles tend to rust.
Gate valves like the one shown on this raw-water intake are still fairly common on old boats, but marine surveyors don't look kindly on them -- for good reason. [links]