sea water intake gate valve replacement

[jennyo]

I have a 1964 cris craft wood skiff that i want to replace the old
sea water intake gate valve.can i replace it with a ball valve and a flanged
adapter fitting or should i replace it with a flanged thru hull sea ****.

Thanks for any advise.

 

[Mischief Managed]

Re: sea water intake gate valve replacement

I have a 1964 cris craft wood skiff that i want to replace the old
sea water intake gate valve.can i replace it with a ball valve and a flanged
adapter fitting or should i replace it with a flanged thru hull sea ****.

Thanks for any advise.

Ball valves should never be connected to through hulls, they have different threads. Through hulls and seacocks have NPS (straight) threads, ball valves have NPT (tapered) threads You can mate tapered and straight threads together, but it won't be very strong since you can't get many turns on the junction. Perhaps you can find an flanged adapter fitting with NPT threads, but I have never seen one.

 

[shrew]

Re: sea water intake gate valve replacement

As long as we're talking about proper Bronze fittings, then a Bronze Flanged Adapter with a male threaded connector, and a bronze NPT threaded ball valve is fine. Personally, I think it makes it easier to clean the inside of the running pickup and inspect and service the ball valve anyway. I've used both teflon tape and pipe dope and not had issues with leaking at the threaded connector.

Update: Simutaneous post. My flanged adapter plates are NPT threaded. Grocco makes them i believe. The ball valve is the marine type, not a home store one.

 

[Mischief Managed]

Re: sea water intake gate valve replacement

Ball valves should never be connected to through hulls, they have different threads. Through hulls and seacocks have NPS (straight) threads, ball valves have NPT (tapered) threads You can mate tapered and straight threads together, but it won't be very strong since you can't get many turns on the junction. Perhaps you can find an flanged adapter fitting with NPT threads, but I have never seen one.

Oops, I just found out that Groco makes a flange with NPT threads specifically for using a ball valve and a seacock... I suspect buying the two parts (flange and ball valve) might cost more than a seacock.

 

[jdlough]

Re: sea water intake gate valve replacement

I had a couple of new bronze thru-hulls that were NPS. I wanted to connect them to bronze NPT ball valves.

I took the thru-hulls to Home Depot plumbing dept and talked the guy into tapering the threads on his die/threading machine, turning them into NPT.

Took 2 minutes.


(Actually, the thru-hulls started off being NPT, but they were too long and I cut a couple of inches off them, which turned them into NPS, so I had to taper the new cut end)

 

[cyclops2]

Re: sea water intake gate valve replacement

For many years we have converted from gate to ball valves. Faster acting. NO DOUBT if valve is fully open or fully closed. We found the valves to be very free from the problems of gates. Corrosion & leaking.

One of the times when newer is better.

 

[sasto]

Re: sea water intake gate valve replacement

Ball valves should never be connected to through hulls, they have different threads. .

I would never use a gate valve....nowhere.. ever....on a boat.

 

[cyclops2]

Re: sea water intake gate valve replacement

A warning about some companies ball valves.

Some will state the inlet size of say 2". But when you flip it to fully open. You see that there is only 1 1/2" of ACTUAL opening.

Shop around longer. We went to industrial suppliers that do a FULL pipe size when open. Why not ? Beats me why they cheat. Maybe every 200th valve is free to them.

It is so nice to look into a engine area & see all valves with the handles pointing down & instantly know that the overheating is from the blocked inlet trash strainer. Hopefully.

 

[bruceb58]

Re: sea water intake gate valve replacement

I would never use a gate valve....nowhere.. ever....on a boat.

I agree. You never know if they are all the way closed, all the way open or somewhere inbetween when they fail.

 

[dingbat]

Re: sea water intake gate valve replacement

The biggest issue with in-line valve on an intake is the possibly that the connection will fail due to vibration or corrosion. If the connection does fail, you have no way to shut off the intake and you are sunk. A seacock elevates that issue