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Closing sink through hull

Nov 18, 2015
18
Sirius 21 Oyster Bay, NY
Hey everybody, I am now the owner of a brand new used Sirius 21 (1978). I keep in the water and will be using during the winter months here in NY. The sink through hull makes me a little nervous. We just do day sailing in the winter and have no use for the sink. Has anyone closed that through hull? I don't want to use a bung due to freezing temps. I have a few ideas, but any input would be great. thanks Chris
 

kito

.
Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
Any thru hull that's below the waterline should have a seacock. I actually added a seacock to my head's sink that was 8" above the waterline. Just in case my pump goes out and I have a leak and the waterline begins to rise :)
 
Nov 18, 2015
18
Sirius 21 Oyster Bay, NY
That is correct. The sink drain itself is threaded so maybe there was a threaded plug for it at one time. There is a metal pipe coming out of the hull which is attached to a heavy rubber/plastic tube which runs to the sink drain. There is no sea cock involved. My big concern is the rubber pipe splitting or cracking. I know I have to put in a sea cock or just cap the metal pipe off. I was just wonder if any other sirius owner had experience with this issue. Chris
 
May 24, 2004
6,635
CC 30 South Florida
Perhaps a picture would help. I'm not familiar with the Sirius and don't know how many responses you may get from other owners. Let's start with the basics, is your discharge port above or below the water line? Is the top of the metal tube above the waterline? How is the plastic/rubber tube connected too the metal tube? You will need to conduct a risk assessment in order to determine what action if any needs to be taken. If the discharge port is above the waterline no seacock is required as it is deemed you have two sources of protection, the air gap between the thru-hull and the water plus the integrity of the tube metal/plastic going up to the sink. If the discharge port is below the waterline but the top of the metal tube is above the waterline you only have a single source of protection but at least is metal which will withstand some shock without breaking. There should be a seacock but in the old days they did not deem it necessary as long as the metal tube projected above the waterline. The largest risk would be posed by corrosion and the tube would require thorough and frequent inspections. The only way of improving safety would be to install a seacock as you could plug the metal tube at the top and it could still break at the base. Now the worst situation would be if the metal tube is short and you have the plastic/rubber tube below the waterline. Now the solution to this problem would be to get a quality discharge hose that may fit over the metal tube and use double clamps to secure it and then connect to the sink drain. Just determine what is your actual risk and then determine what you would need to do. If you notice in any of the cases I have not given consideration to capping the metal tube as it would not bring any additional benefit to those suggested fixes and loosing the use of the sink for no gain is not warranted. This is just food for thought as I really do not know what your lay out is. In the past and now days I continue to rely more on frequent inspections of the thru-hulls, hoses and clamps than I rely on the actual seacock valve. Our sink valve is located in an awkward place and we keep it open at all times. We do exercise it periodically to insure its working condition but the last time it was closed for any period of time was in preparing the boat for a hurricane.
 
Jul 14, 2015
840
Catalina 30 Stillhouse Hollow Marina
That is correct. The sink drain itself is threaded so maybe there was a threaded plug for it at one time. There is a metal pipe coming out of the hull which is attached to a heavy rubber/plastic tube which runs to the sink drain. There is no sea cock involved. My big concern is the rubber pipe splitting or cracking. I know I have to put in a sea cock or just cap the metal pipe off. I was just wonder if any other sirius owner had experience with this issue. Chris
There should be shut off valve installed at a minimum.
 
Aug 19, 2013
129
Sirius 22 Minneapolis
Here is a photo of the OEM installation. Not a true seacock but a bronze shutoff valve. Just a hose connected to the thruhull is a bit risky to put it mildly.
seacockvalve_zps86885fd2.jpg
 
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Nov 18, 2015
18
Sirius 21 Oyster Bay, NY
Thanks for the pic. That is what I was thinking about doing. I was surprised that the boat was designed without a seacock on the thru-hull. Maybe its "trailer sailor" category led to the designers making that decision. Chris