Seacock, Nps or Npt?
- Thread starter toliver
- Start date
The main problem with screwing a NPT (tapered) ball valve onto a NPS (straight) thru-hull is not leaks, but strength. You will only be able to turn the ball valve 1.5 to 2 turns before it jams. Probably won't leak, but now you have a pretty good lever working on a bronze thru-hull with only around 1/32-inch thickness and no structural support. Corrosion, or a dropped box or misstep and the ball valve snaps off the thru-hull. Quick! Did you remember to tie the right size tapered wooden plug to the thru-hull? And where's the damned mallet!
Groco makes a really useful "hybrid" adapter that allows you to have structurally sound fitting, yet replace the ball valve without removing the thru-hull. Did six of these on my 84 Hunter 34 to get rid of the execrable gate valves. And use fiberglass donuts instead of cheap wooden backers. Expensive and time-consuming, but very solid.
Groco makes a really useful "hybrid" adapter that allows you to have structurally sound fitting, yet replace the ball valve without removing the thru-hull. Did six of these on my 84 Hunter 34 to get rid of the execrable gate valves. And use fiberglass donuts instead of cheap wooden backers. Expensive and time-consuming, but very solid.
It appears that the PO attached a 3/4 to 1/2 reducer on top of the old gate valve. Then screwed in a 90 degree adapter that ended in a 3/4" pipe where the hose is clamped. Strange.... I guess they couldn't find one of these: http://www.overtons.com/modperl/pro...rko4Xn9-xmk_YBUsO3-30p-sHvfqr5tnjIaAj308P8HAQ
That setup is going to slow the flow of water and possibly be a choking point for debris.
That setup is going to slow the flow of water and possibly be a choking point for debris.
Thank you...but I do not understand...are you suggesting keeping the reduction from 3/4 to 1/2 and just add the 90 with barbs on the end to grasp the hose better?
Right... Toss the reducer, elbow, and pipe and replace with a single Groco 3/4" elbow with 3/4" nipple.
Thanks, I ordered that 90 degree 3/4"on both ends bronze fitting from WM today...will update forum when item is delivered and installed...you must have a nice keen eye for "strange" plumbing setups. I believe your reply was true and really well stated.
Problem solved...Here is a pic of updated Ball Valve installation completed today with a 3/4" 90 Elbow.
WM excellent service with 2-day delivery.
Thank you to all who responded to my question here and for all your great comments and advice.
You all reminded me that there are several different levels of completing any boat repair and/ or update from "poor/ dangerous" to "excellent/ super safe".
As sailboat owners repair decisions are often made from a mix of personal choices according to safety, expense, availability, complexity, skill level, health, sailing location, boat age and more.
For my personal situation a "good/ safe enough" installation is fine and I can sleep at night.
Thank you especially to "heritage" who as far as I know is the only forum reader out of 800 views to notice the strange and incorrect original seacock set-up on my sailboat and bring it to my attention. I now feel that I have a safer, simpler and more efficient seacock set-up and better engine cooling system due to "heritage" who took the time to analyze and help my particular situation.
Thank you, thank you...I really appreciate your time and expertise.
I am pleased and learned a lot from everyone's comments.
To me, this Forum thread is a fine example of how helpful and informative SailboatOwners.com can be.
I am grateful to you all.
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Not true. Next time you are in a marine parts store, go get two of them and only screw them on halfway and then see if you can pull them apart. Not going to happen. There would be enough gap to allow water to seep through, but there is strength in it. Just about all boat builders have been doing it this way for 30 years. Is it best? No, but it clearly works. And if you don't bond your thru-hulls, they will not corrode (assuming they are bronze).
When I was a kid I jumped off the roof with a custom blue tarp parachute. It worked. When I jumped off the bridge in Twin Falls I did not use the blue tarp parachute.
Just because a kludged thread mismatch arrangement works most the time is no argument for deliberately doing it wrong,.
Just because a kludged thread mismatch arrangement works most the time is no argument for deliberately doing it wrong,.