through hull fittings and valves
- Thread starter woodster
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Scott,
By accepted definition any valve below waterline connected to a thru-hull becomes a seacock or sea-valve. Take the valve off the thru-hull and it is a valve/cock, put it back on and it's a seacock/seavalve.
When someone makes mention of a "proper" or "traditional" seacock it will have a wide flange and a means of securing the flange to the hull other than just the thru-hull fitting. Still a seacock though.
The word seacock stems from "cock" meaning:
1- A faucet or valve by which the flow of a liquid or gas can be regulated.
Put sea in front of it and you have seacock. Cock is just another word for valve. Even a gate valve is technically a seacock if used for the purpose of shutting of water flow on a boat. There are different types of seacocks that can be used, flanged with ball, flanged tapered cone, flanged adapter with ball valve, valve on a thru-hull, flanged gate (not seen much any more) and non-flanged ball or gate or any other combination.
When you buy from a chandlery they call a flanged valve a "seacock" because that is about the only thing it can or will be used for with the built in flange. If you buy a ball valve you could use it to shut off fuel flow, which is not a seacock, or in a domestic water situation. Not until you connect it to a flanged adapter or thru-hull does it make it a seacock...
Confusing, I know.....
I do believe that we have to get the terminology correct. Some people get upset because it looks like we are mincing words, but this is very serious topic and not everyone wil "know what you mean". Thanks for clearing up the definitions for us, and the primer on cock(s).
BTW when I was installing the seacocks, I was explaining to my wife what I was doing and using all the terms for these things. She replied with "boats are perverted"
BTW when I was installing the seacocks, I was explaining to my wife what I was doing and using all the terms for these things. She replied with "boats are perverted"
Because they would not seal reliably. With a flanged adapter or true seacock, the NPS section of the through-hull isn't being relied on to seal out the seawater, the sealant between the flange and the hull is. If you chased the NPT threads out to NPS, the only the valve wouldn't seat down on the threads like it does with NPT threading and the chances that the ball valve would become loose from working the handle is much higher without that tight fit.
Because the wall thickness of the thru-hull would be compromised with a taper. They were never designed nor intended to have a tapered thread cut into them and the wall thickness was not designed for this ahead of time.
You can buy "combination thread" thru-hulls which is simply a band-aid approach. With combination threads they cut the peaks off the first few threads..
this thread has had very good replies thanks everyone...
now to add to the fire ....some of the plumbing has street L's prolly to maintane overhead clearance/direction regulation ect ...i do have concerns about that ....should the street L's go between the through hull and the valve...it seems to me that if some thing should break that would be the most likely place and if that happened i might be very hard to plug the hole with a wooden plug with out going over board and driveing it in from the out side under the hull.... also what type of sealant or would teflon tape surfice
regards
woody
now to add to the fire ....some of the plumbing has street L's prolly to maintane overhead clearance/direction regulation ect ...i do have concerns about that ....should the street L's go between the through hull and the valve...it seems to me that if some thing should break that would be the most likely place and if that happened i might be very hard to plug the hole with a wooden plug with out going over board and driveing it in from the out side under the hull.... also what type of sealant or would teflon tape surfice
regards
woody
If clearance permits I would put the elbows after the ball valve not in between. The fewer things you have to fail between where the water is coming in and where you can stop it(the ball valve) the better it is. But sometimes you don't have a choice because you will have plumbing prairie dogging out of the floor panel.
I installed all the flange adapters and then capped them with pvc caps. After I put the boat in the water and I had the money to do all the plumbing, I unscrewd the pvc caps and inserted a rubber stopper in the hole. I then put pipe dope ONLY on the malke thread, so not in the ball valve female threads. I pulled the stopper out and screwed on the ball valves(magically changing them into seacocks).
If you put pipe dope on the female threads, when you thread it together, the pipe dope gets forced up into the fitting. I'm not sure if that tip is on Mainesail's website, but he told me about it when I was installing mine.
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