What is the Black Fitting in this Sink Drain?

[endoftheroad]

PVC is okay with salt water,it's the sun's uv that it doesnt agree with. PVC inside is usually considered fine to use, but use with extreme caution for reasons such as the previous poster described, such as vibrations, extreme temperatures and cracking of overtightened fittings. Using below the waterline probably isn't a good idea.

In my attached picture is the fitting I'm replacing, it was on my 40 year old perfectly functioning Groco seacock that's used for my galley sink drain.
On the fitting it is stamped Dixon V & C CO. Tuff-Lite. I found online that it's a Polypropylene fitting. It seems of great quality, the rubber gasket seems much too old for my comfort. I would like to know if this is an original fitting on my Westsail 32? Or perhaps they used Bronze tailpipes originally?

[endoftheroad]

It's looking like I'm going to use hose and a Marelon fitting at the seacock as well as spin on a Marelon on each of my plastic sink drains.

Forespar Marelon Straight Tailpipe / Hose Connector

[geoffh]

I use PVC with confidence(out of the sun) but I do agree with others that a flexible coupling be used at the seacock/thru hull.A tip I could offer is to use plumbers tape on your threaded joints, but I combine this with thread seal paste/liquid. It is readily available and after 35years of plumbing I can guarantee no leaks first time when I use the jointing compound.Cheers

[Hudson Force]

Originally Posted by sabray

For my boat there is no pvc below the waterline attached to a thruhull so that a failure of the pvc could sink the boat. One problem I have seen. A tightened pvc schedule 40 fitting that cracked because it was overtightened or cracked because it was so tight that when the temperature changed and dissimilar materials expanded or shrank at a different rate it cracked. For an extra 20 bucks you can avoid that problem. Maybe a place or 2 where pvc could get someone by.

Some good points by sabray here,- application is key. I would never fit PVC directly to a through-hull; however, I would accept it in the manner that the white T-fitting is seen connected to the hoses in the post #1 photo. Even the best materials can fail if they are misused or overtightened.

[endoftheroad]

I need a good below the waterline hose. Any suggestions? It should be somewhat flexible and of premium quality. The waterline is just a couple inches below my sink. I'm doing this right so I don't have to close my Groco while at work daily as the valve is in a hard to reach space.
Thanks

[s/v Jedi]

Originally Posted by endoftheroad

I need a good below the waterline hose. Any suggestions? It should be somewhat flexible and of premium quality. The waterline is just a couple inches below my sink. I'm doing this right so I don't have to close my Groco while at work daily as the valve is in a hard to reach space.
Thanks

Corrugated exhaust hose.

[Hudson Force]

There's lots of good flexible reinforced marine hose that is widely available. The risk, once assured that the hose is not subject to undo crimping or chafe, is at the fittings. Make sure that the hose barbs are of proper size and long enought to hold two all stainless hose clamps best secured in opposing directions and firm, but not scoring the surface of the hose. Sometimes hose that is difficult to slide onto the hosebarb can be slightly expanded with a hot air hair dryer with a little hand lotion used as a lubricant that will not retain this slippery condition once dry.

[endoftheroad]

Originally Posted by s/v Jedi

Corrugated exhaust hose.

I just checked out Vetus exhaust hose. They have 1-5/8 id, I need 1-1/2. Whats up with that?

[endoftheroad]

Originally Posted by CaptForce

There's lots of good flexible reinforced marine hose that is widely available. The risk, once assured that the hose is not subject to undo crimping or chafe, is at the fittings. Make sure that the hose barbs are of proper size and long enought to hold two all stainless hose clamps best secured in opposing directions and firm, but not scoring the surface of the hose. Sometimes hose that is difficult to slide onto the hosebarb can be slightly expanded with a hot air hair dryer with a little hand lotion used as a lubricant that will not retain this slippery condition once dry.

Yes, I'm looking at some of these hoses at Defender. I am using smooth bore hose clamps and doubling them up in opposing directions. Marelon tailpipes, all the good stuff. My final decision is for a premium flexable below the waterline hose. Any personal favorites?

[Hudson Force]

'depends somewhat on the flexing required. If you have a significant bend I'd select Defender's Item# 501705 clear w/black helix 1-1/2". Item#500582 would suit without a harsh bend and allow an internal view and item# 500552 would suit at the least cost. Any of these hoses would be robust for your application as a sink drain.

[endoftheroad]

Originally Posted by CaptForce

'depends somewhat on the flexing required. If you have a significant bend I'd select Defender's Item# 501705 clear w/black helix 1-1/2". Item#500582 would suit without a harsh bend and allow an internal view and item# 500552 would suit at the least cost. Any of these hoses would be robust for your application as a sink drain.

Thats good news because I just bought #501705!

Thanks very much.

[jgbrown]

Originally Posted by endoftheroad

I just checked out Vetus exhaust hose. They have 1-5/8 id, I need 1-1/2. Whats up with that?

Needs to be aggravating, it's a boat thing I think. My sink drain was 11/2, but sea cock 11/4. Previous owner wrapped that in electrical tape and called it good...


I used sanitation hose for my sink drain not exhaust hose. Flexible, economical(already sitting around) and doesn't collect smells.

[endoftheroad]

It's done, I feel good about it.
I used 1-1/2" Trident XHD hose, it's really tough stuff and approved for below waterline applications, I got it from Defender for $4.19 per foot, only needed 3 feet.
I double hose clamped all connections with premium smooth clamps. I used Marelon tailpieces at seacock as well as at drains bottoms and taped up the threads suffeciently. And a quality nylon tee.
As already stated my waterline is only about 4 inches below sink bottoms, I live at anchor and have been opening and closing my 40 year old Groco seacock drain daily, it's in a tight location. I'm comfortable leaving it open daily now while at work, for extended periods I'll close the seacock.
It's a very ridgid fit, it would take a sledge hammer with a good swing to break it free, I had to sawzall the holes in the shelving larger hence the messy sawdust look in the picture.

[sabray]

Is that a npt fitting on the groco.. I have a few old groco and they are nps thread. I can't find marelon female nps fitting that are seated like the groco tail piece. Maybe groco made these old fittings with npt thread but I have not seen them.
If they are nps where did you get them?

[endoftheroad]

Originally Posted by sabray

Is that a npt fitting on the groco.. I have a few old groco and they are nps thread. I can't find marelon female nps fitting that are seated like the groco tail piece. Maybe groco made these old fittings with npt thread but I have not seen them.
If they are nps where did you get them?

Haha....I knew someone would ask that question. In fact I started writing about it in my above post and then erased it.
Groco has a sheet out where they say its okay to mix the threads given that they are generoussly taped or doped. Turns out it's fine to do it on "low pressure only applications" such as seacocks etc. Where it really becomes a problem is with steam applications or other high pressure systems. Or even moderately pressure systems. Seacocks are very low pressure.
Another common argument is that npt to npt connections sometines only spin on a few threads making the connection vulnerable to breakage if something heavy drops on it. For this particular low pressure application with the addition of good ptf tape the Marelon fitting went on snug and fully threaded onto the seacock. The water has along way to go through all those threads and tape and if it ever did it would be minimal seepage.
I'm not recommending anyone to do this but I'm comfortable with the Marelon npt female on my Groco sv nps seacock.

endoftheroad