Thru Hull Blues

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Hugh

Anyone out there have suggestions on my thru hull replacement project? Step one is done, I have four open holes in the boat. I went out and bought 4 bronze seacocks, with the accompanying thru hulls, tailpieces and etc, and now its been sugested by the "guy" at the marina that all those weighty seacocks may be overkill, since my hull is no more than 1/2 inch thick at the most. The size I guess of the required backing plates will cause the installation to take up too much room in some locations. The alternative that has been suggested is that I should use simple bronze ball valves screwed onto the thru hull. Even though they would cut off the thru hull so the valve screws right down to the lock not and backing plate for stability, and even though I'm making sure someone keeps the installed thru hull from turning as they screw the valve down, I'm very concerned because the thru hull is NPS threads and the valve is NPT. Still a couple other "boat fellas" around say they do it all the time. Are they a little stupid or am I a little obsessive? The second issue is that instead of a saftey seacock at the raw water intake, I'm planning just a 3-way valve installed so that the engine can either draw from the deep blue sea, or from another inlet of my choosing for winterizing or emergency. Why will that not work (assuming the NPT/NPS issue is solved)? Now I don't want the perfect boat. I feel like the best solution would be to install seacocks, but the valves are much cheaper, and they will fit in my tight spaces. It does seem a strech to install a 20 pound bronze fitting for my head sink drain. Can I get by safely for coastal use with this set-up? Thanks for the help. Hugh
 

Rick D

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Jun 14, 2008
7,187
Hunter Legend 40.5 Shoreline Marina Long Beach CA
NPS Valves

You can order the valves in NPS thread also. That's the way to go. RD
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Seacocks vs. ball-valves

I used NPT ball valves for years before I got around to replacing them with seacocks. The issue with seacocks on my H37C was the size of the thru-hulls, 1/2". The smallest seacock is for 3/4" so that necessitated bigger holes and new thru-hulls. The picture is the original engine thru-hull setup. I use a T-valve on my engine seacock. But for selecting the engine or the air-conditioning as output. My big galley drain is still the original gate valve. I don't know if they even make a ball valve or seacock that big.
 
H

Hugh

Thanks for the info

I finally decided to go with Bronze Thru-Hulls and Marelon valves. For some reason the Bronze valves locally available were all NPT, while the Marelon are NPS, like the thru-Hulls. The marelon valves are much lighter, and fit better in some of the spaces too. I still used a bronze seacock on the engine intake, with the 3-way valve fitted on top. Two valve handles there to screw around with, but I'll just have to tape off the upper handle, except in emergencies, or for winterizing.
 
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