Changing a thru hull / ball valve at sea
by SV Crystal Blues 8 Jan 2018 19:19 UTC
Diver Ryan was faster and cheaper than a haul out © Neil Langford / SV Crystal Blues
We've done this a couple of times now, and it's a really simple and fast maintenance job. Finding a dripping leak in a ball valve on the engine sea water inlet, we investigated and found it was seeping through the seal to the handle. It had given us 15 years of service, so I was happy to replace it. We located the spares we carry and selected the right size - 1.25" in this case.
Next we needed a diver, and in chilly St. Augustine that was not going to be the Admiral. No way said she! A call to the local cruiser's net identified a willing local, so we scheduled the job for the next day at slack tide. Note that Crystal Blues has skin fittings (thru hulls) with stand pipes that are threaded, to allow the ball valves to be screwed on and off, without actually effecting the skin fitting.
Diver Ryan arrived right on time, and as he prepared his gear and suited up I started on my own work sequence :
- Close the faulty valve and loosen the hose clamps on the hose connected to it.
- With the hose clamps out of the way the hose tail (hose barb) is unscrewed from the valve. It rotates easily inside the hose, meaning you don't ever have to fight to actually get the hose off the hose tail. This is made easier if you always apply a little silicone sealant to the hose tail during assembly, before sliding the hose over it.
- Once the hose tail is disconnected the action begins, Ryan the diver enters the water with our trusty toilet plunger and holds it over the water entry point. He taps three times on the hull to signal he's ready, and I open the ball valve - voila, just a tiny amount of water enters the boat, before the pressure differential forces the plunger tightly against the hull and seals the entry.
- Unscrew the old ball valve, clean up the threads on the stand pipe, apply new PTFE tape and then screw on the new valve. Close the valve, tap three times on the hull and the diver removes the plunger. Simple!
- Some time later I re-attached the hose tail and re-fastened the hose clamps. Job done.
While many older boats still have skin fittings that incorporate the valve, many newer vessels are built with separate components which allows this process to work just fine. From my perspective, $80 for a diver for 30 minutes is a lot better than $800 for a haul out, just to change a ball valve.
This article has been provided by the courtesy of SV Crystal Blues.