Splicing domestic water hose

Our 1981 36CL has the original rigid black plastic domestic water piping. Fearful of opening a can of worms over the years I have avoided tampering with it. However there are some projects I would like take on which mean cutting into the pipe. I really do not want to re plumb.
Are there fittings available (I think of Shark bite) which allow adding Pex hose for instance.

Unicorn V
#633

Welcome aboard. I absolutely hate working on plumbing since I am not good at it and it always leaks. But with Shark Bite fitting you will probably ba able to do what you need to. Before you cut any I would get an accurate measurement of the OD and go to a real plumbing store and ask if they have fittings that will work. Good luck.

Yes, measure twice, cut once and get the right fitting. And know it it's mm or inches. There are several sizes that are so close it's hard to tell them apart. In a lot of water systems, it's common to find 15mm tubing and 1/2 fittings in the same system.

As for finding a good plumbing store that knows there stuff... good luck. Those guys are disappearing. Ain't gonna find it at Home Depot. I've had better luck calling the techs at the manufacturer.


I could make an argument, if adding a line, to replace it with SeaTech. However, sometimes you just can't find a fitting or part that makes it compatible and have to use a Fernco fitting to make it work.


SeaTech tech support is very good.

Hi, When working with that black ridgid tubing on a friends older GB we found intalling hose barb adapters to allow the use of Pex was a lot easier when we gently warmed the open end of the black pipe with a heat gun. It slightly expanded and softened allowing a 1/2 barb adapter to slide right in. Once cooled a hose clamp completed the job. These connections never leaked for us. John P

Thanks for the responses. I’m now not so worried. The plan is to add a mixing valve. Are there any hard lessons I might avoid with that?
Unicorn V

I have made modifications into that black pipe. I used barbed fittings after considering shark bites. I did not take measurements of the ID, just went ahead and used what I had available, no leaks after a year or so. I will guess it was 1/2 inch ID. maybe 3/8. Point is regular available stuff works.
Use heat gun on the hose to soften before inserting the fittings and hose clamp before it cools completely.

That grey plastic pipe from the early 80's is Qest. (No "u.") Don't assume a SharkBite or other fitting will work unless it says so on the package.

The good news is that stuff is pretty easy to work with. They are designed to be connected finger tight. Stop when you hear a squeak. All the threaded fittings are standard threads, so you can replace any section with newer products. And you can still buy the Qest fittings if you want.

Qest got a very bad name from failures in homes inside walls. I'm not sure about the details, but the Qest fittings in my 1980 boat have held up just fine. I've upgraded to PEX in places where I've added or made major changes, but I have found no reason to take out what's been working well for over 40 years now. In fact, those hand-tighten connections make it easy to winterize the potable water system. I just pull the connection at the bottom of the tank and stick the hose into a bottle of antifreeze. Try that with SharkBite connections!

CaptTom said:

That grey plastic pipe from the early 80's is Qest. (No "u.") Don't assume a SharkBite or other fitting will work unless it says so on the package.

The good news is that stuff is pretty easy to work with. They are designed to be connected finger tight. Stop when you hear a squeak. All the threaded fittings are standard threads, so you can replace any section with newer products. And you can still buy the Qest fittings if you want.

Qest got a very bad name from failures in homes inside walls. I'm not sure about the details, but the Qest fittings in my 1980 boat have held up just fine. I've upgraded to PEX in places where I've added or made major changes, but I have found no reason to take out what's been working well for over 40 years now. In fact, those hand-tighten connections make it easy to winterize the potable water system. I just pull the connection at the bottom of the tank and stick the hose into a bottle of antifreeze. Try that with SharkBite connections!

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I thought the grey pipe used in the GB was polybutylene? Or is that the same as Qest? SharkBite has polybutylene to Pex fittings that I had hoped to use when the time comes.

Thank you Capt Tom...very interesting. If the treads are standard then I should be able to just splice in the short lengths of Pex that I need assuming I can still obtain the fittings?

Unicorn V

If it is the grey pollybutal pipe you can get a pex adapter for it there are 2 different crimp rings. I removed all of this pipe on our boat and went back with pex. We had several issues none causing damage and pex is super easy to work with. Lowes and home depot sell the transition fittings

JMcJ said:

Thank you Capt Tom...very interesting. If the treads are standard then I should be able to just splice in the short lengths of Pex that I need assuming I can still obtain the fittings?

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A picture is worth 1,000 words...

CaptTom said:

A picture is worth 1,000 words...

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Nice work and nice clean bilge

sailormike said:

If it is the grey pollybutal pipe you can get a pex adapter for it there are 2 different crimp rings. I removed all of this pipe on our boat and went back with pex. We had several issues none causing damage and pex is super easy to work with. Lowes and home depot sell the transition fittings

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Thanks

My 1990 GB49 uses a gray pex according to the stamping on the tubing. I have use the 1/2 inch pex with the compression fitting to fix several minor leaks. The leeks we caused by the original aluminum compression rings touching the copper bonding strap which caused the ring to crack/break at the contact point. The remaining aluminum ones were in good condition. The new compression rings which are available at lowes solved the problem along with lots of different fittings and tubing.---- easy stuff to work if you have the compression tools.

Although I’ve been a TF member for years, I did not actively participate , instead concentrating on IAGBO. When it dissolved I wandered aimlessly!! The response to my post has been so encouraging and confirms my faith in GB owners. Thanks guys. And Capt Tom your photo indeed says it all. I certainly envy the state of your engine room. I’ll never get there.

Unicorn V

I have been a TF member for quite a while but not an active participant, instead focussing on IAGBO. When it went dissolved I wandered aimlessly!!! Your responses to my post are really encouraging. Thanks guys.

And Capt Tom the photo says it all but also the standard to which most of us can only dream. Wow.

Unicorn V

Please keep in mind "Shark bite" and other press on fittings are intended for use in residential buildings. Under vibration tests the components that grip the pipe and hold it in place will cut into the tubing. I have installed them in boats and motorhomes both with NO problems. But was informed by the manufacturer that they should not be used in an application that would expose the fittings to extreme vibrations. I have had no leaks in any of my installations. ALSO a residential water pump vibrates like crazy and the manufacturer says that they are OK for use on residential water pumps. I honestly feel the products were not tested and approved for marine or motorhomes so they can not recommend for such. That being said your installation is absolutely lovely and a work of art to be proud of.

Cny said:

Please keep in mind "Shark bite" and other press on fittings are intended for use in residential buildings. Under vibration tests the components that grip the pipe and hold it in place will cut into the tubing. I have installed them in boats and motorhomes both with NO problems. But was informed by the manufacturer that they should not be used in an application that would expose the fittings to extreme vibrations. I have had no leaks in any of my installations. ALSO a residential water pump vibrates like crazy and the manufacturer says that they are OK for use on residential water pumps. I honestly feel the products were not tested and approved for marine or motorhomes so they can not recommend for such. That being said your installation is absolutely lovely and a work of art to be proud of.

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Ah, yes, extreme vibrations. If your boat is producing extreme vibrations, enough so that the plumbing is also vibrating extremely, then you have problems way more than a plumbing issue. I have a pair of Lehman 120s known to shake a bit at idle. Yes, a bit of vibration but extreme (?), not even close.

JMcJ said:

And Capt Tom the photo says it all but also the standard to which most of us can only dream. Wow.

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That picture was taken right after I'd installed the new water heater, before which I'd pulled the old tank and the plumbing in that area and painted. Believe me, there are parts of my ER that I'm not as proud of.

Cny said:

Please keep in mind "Shark bite" and other press on fittings are intended for use in residential buildings. Under vibration tests the components that grip the pipe and hold it in place will cut into the tubing.

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I'd heard that too, and since that picture was taken I've invested in a PEX crimping tool. One of the better investments I've made. Some of those SharkBite fittings in the photo have already been removed, and I'll be re-working that area again in an attempt to mitigate the pump noise. It's right behind the V-berth bulkhead and if we run the water at night it'll wake anyone sleeping there. Anyway, I've had no problems with the SharkBites but I am going to limit their use to only those fittings which need to be removable going forward.

I honestly feel,,,,, that the shark bite fittings were tested under conditions for residential use and not for rv or marine use. Vibrations such as hitting potholes or going over waves were not in the test conditions. We as consumers have assumed the risk of incorporating products into our systems and testing them for the company. Like I said I have had NO leaks in any of the builds I have undertaken. Also as was brought up most boats don't vibrate as much as a residential deep well pump. Shark bite's rep said that the fittings were fine for a direct connection into the cast iron pump. I have used Pex crimp also in residential applications, that was the first step in making plumbing a job tbat more people could take on. The crimper is an investment, but the rings are reasonably priced. Shark bites are up there in price but make the job easy. Doing some math in my head... a hand full of 3/4 or 1 inch shark bites would pay for a pex crimper. I am sure I speak for many when I say we would love to see pictures of your updated system when you get it completed. Your work is inspirational.

Our 1975 boat was plumbed with polybutylene tubing and I often used John Guest push fittings from Home Depot to make repairs to the many leaks that developed. Getting tired of that, I am now replacing all the plumbing with PEX A and using an expanding tool rather than making crimps.

FWIW, I never had any problems with the John Guest fittings, only the brittle polybutylene tubing. At one point I had 5 streams of water coming off a single 4' section of tubing!

SharkBite fittings

I have a mix of original Grey Poly tubing and Pex - SharkBite fittings and barbed with clamps throughout my boat - no leaks. I did use a section of the "flexible" SharkBite SS clad tubing to make a offset connection - might work good for a water pump connection..

There some places that had tight tolerances, "tee's" for example that using a SharkBite connector would have created more work to rearrange, so I used barbed connections.

My boat has been in salt water it's entire 32 year life, until earlier this year (Yea!), some of the aluminum clamps that were used on the grey-poly connections had corroded and were leaking (ie: under the engines - close to impellers and where salt water had leaked from anode changes) so try and inspect those connections if possible.

Lastly, if you are going to use SharkBite connections, be sure to get the tool to remove them!

Greggnvt said:

I have a mix of original Grey Poly tubing and Pex - SharkBite fittings and barbed with clamps throughout my boat - no leaks. I did use a section of the "flexible" SharkBite SS clad tubing to make a offset connection - might work good for a water pump connection..



There some places that had tight tolerances, "tee's" for example that using a SharkBite connector would have created more work to rearrange, so I used barbed connections.



My boat has been in salt water it's entire 32 year life, until earlier this year (Yea!), some of the aluminum clamps that were used on the grey-poly connections had corroded and were leaking (ie: under the engines - close to impellers and where salt water had leaked from anode changes) so try and inspect those connections if possible.



Lastly, if you are going to use SharkBite connections, be sure to get the tool to remove them!

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Even with a removal pliers, Sharkbite fittings are very difficult to release. John Guest fittings are a bit easier.

So my 1980 GB36 classic has the black plastic. The only label I can read is Class D. The current fittings are Kuterlite. One of the lines has sprung a leak so I need to figure out the best connector. The OD measures 0.67" so a sharkbite would not work as they are for 0.625" od. Any suggestions beyond a bard? I should also add that the Kuterlite fitting although 1/2" pipe are NOT a tapered thread but rather a parallel thread so seating a NPT thread takes lots of tape and pipe compoud.

I ended up using 1/2" barb coupling with hose clamps and that seem to be holding fine. The id of the black plastic is 0.50" and the od is 0.70" so standard pex does not work.