A unique British made product is available in the US, enabling repairs to be made to sea-cocks, and ball valves, without lifting the boat. Everybody hopes they will never have to touch the through-hull fittings, but you should be prepared, because stuff happens on boats.

The age-old remedy for working on through-hulls has always been the tapered wooden plug. These plug holes fine, but they have limitations, for instance, it's very difficult to replace a ball valve using a wooden plug. With a Sea Stopper it's easy.

Sea Stopper is a 3 3/4”inch diameter mushroom shaped flexible urethane/rubber umbrella on an 11”inch stem. The principal is simple, you just slide the head of the stopper into a closed sea-cock/valve, then open it and push the stopper right through to the outside of the hull. The umbrella springs open outside, and water pressure seals it against the hull. You can then work on the fitting. Bingo!

Nobody likes to disturb these vital below waterline fittings unless they have to. So how do you know the Sea Stopper will work in an emergency? I had this question answered for me not long ago. 

I decided to unscrew the plastic filter bowl on my AC water inlet for cleaning. The outside part of the sea stopper, which seals the sea-cock opening.The bowl proved impossibly tight to unscrew by hand, so I applied extra leverage with a large pipe wrench. The bowl was attached directly to the fitting with a bronze elbow, (that's a mistake, there should be a flexible pipe between them), and the valve broke completely off the through-hull fitting!!  Water, water everywhere, and not a drop to drink!

A trusty wooden plug was attached to the fitting, as they are on all my seacocks, for just such an emergency. I quickly pushed it into the 1” hole, and stopped the water gushing in. After my heart stopped pounding, I thought about trying the Sea Stopper.

I eased the wooden plug out, then quickly shoved the stopper straight through the skin fitting. Water pressure then forced it against the outside of the hull and it immediately stopped the inflow—totally. I then unscrewed the ball valve from the through hull fitting and lifted it over the stem of the Sea Stopper  Luckily there was still about 3/4” inch of thread protruding through the skin fitting, so after I cleaned it with a wire brush I was able to slide a new ball valve down the stem of the stopper and screw and caulk it on to the skin fitting. This would not have been possible with the wooden plug in place, because the head of the plug was much bigger than the valve; so it would not have be possible to removed the valve.

With the new valve screwed down tight on the skin fitting I then just eased the stopper back out of the assembly and closed the sea-cock. Job done! and I hardly got my hands wet.

The ring in the top of the stem is for attaching a line or bungee cord to keep a little tension on the stopper if the outlet is near the surface, where there is less outside water pressure. The ring is also a good way to hang the stopper from a hook in your bosun's locker.

I have other ten valves on my boat ,so I’m now working my way through all of them, including the larger 1 1/2” size, All without the cost of lifting her.

This stopper is about the cheapest and most effective safety device you can buy for a boat, at only $19.95, including US shipping, and every boat should have one. They also make unique birthday and Christmas gifts. E-mail Roger here to buy the Sea Stopper. hughes_roger@hotmail.com