Thu-hull fittings

[boatminion68]

Since the inside is gutted and we have clear access to all the thu-hulls and they are all gate valves, we decided to rebed the fittings and replace all the gate valves. Here is my question. Can I use standard brass plumbing fixtures (1/4 turn ball valves) I can pick up locally and at a lower cost?

Thanks,

Bill

[msmith10]

There are 2 issues here:
The first is that the threads on ball valves, which are tapered pipe threads, are not compatible with the threads on the thruhulls, which are straight threads. The valves will fit on, but not securely, and it is risky to rely on them. True seacocks have straight threads.
The second issue is the material itself. Seacocks should be bronze or marelon. Plumbing fixture brass will be electrolyzed away much faster than bronze. While you may get away with this in fresh water, in salt water it's setting up a real problem.

[boatminion68]

thr-hull

Thanks for the information.

Bill

[sastanley]

boatminion,

msmith is spot on & his comments about the different thread types is an important detail..there are many places in boats you can cut corners and save costs...this is not one of them.

The cheapest place to pick up marelon seacocks is Defender. My Catalina 30 had the gate valves replaced, but some of the thru-hulls were still pipe nipples. I cut out the pipe nipples, replaced with marelon, built backing plates and 5200'd them to the hull and added new marelon seacocks on top and after threading them on to the thru-hull fittings screwed them to the backing plates. If you check out any of my engine pictures floating around this website, you should be able to pick out the black marelon thru-hull next to the engine which is my raw water intake, and see the backing plate/fitting detail.

You can always get a tow or sail home if the engine breaks, or motor home if the stick comes down, but I'd hate to be treading water in the Chesapeake with my wife & a handheld VHF because I put cheap, improper fittings on my thru-hulls.

I would recommend you read up on this guy's website. I do not have the exact link, but he has an excellent article explaining details related to the straight vs. tapered thread issue & thru-hulls/seacocks/ball valves. After being educated thru his article, that's when I decided to go the marelon route. http://www.pbase.com/mainecruising/

[67c&ccorv]

I'm with Shawn and Smitty - this is not the place to save money when it comes to your safety and hull integrity of the vessel.

[boatminion68]

Thu-hulls

Shawn,

Thanks for the link. Since I'm fairly new to boat restoration I'm learning new things everyday. I will take your advice and look into the marelon thu-hulls and sea cocks.
I appreciate all the help I can get.

Thanks,

Bill

[dvd]

My understanding is that the home depot or other hardware store ball valves are exactly the same as the marine ones except the handle that closes the water off is usually made of a metal that can rust on the cheaper hardware store brands. I used to think that you must use marine grade ball valves until the boat yard I used told me this.

Anyway for whatever its worth

dvd

[67c&ccorv]

My understanding is that the home depot or other hardware store ball valves are exactly the same as the marine ones except the handle that closes the water off is usually made of a metal that can rust on the cheaper hardware store brands. I used to think that you must use marine grade ball valves until the boat yard I used told me this.

Anyway for whatever its worth

dvd

That is what Home Depot and your local hardware store would like you to believe;

...the subject of what is and is not suitable for a thru-hull fitting could take a web site all on its' own;

...FWIW there are many types and grades of fittings manufactued and for sale in the marketplace - some of them are suitable for marine service and many of them are not;

...it is up to the boat owner to get the right one for their vessel

[hanleyclifford]

Regarding the use of Marelon thru hulls and seacocks, I have used them and they have been very satisfactory except when I used a bronze piece as a connector inside the boat. The seal was never perfect and I had to go to all Marelon. The 90s are very restrictive. Before using the Marelon, review your total installation. There is much more variety in tailpieces available for bronze.

[rigspelt]

Agreed: skippers don't sleep well with corner-cutting seacocks. I ended up using a mix of bronze and Forespar Marelon. Getting hard to find good quality bronze even -- shop carefully. We put a cheap one in the ocean at the dock one year on a leash, and by the end of the season it was corroding.

Real pain finding all the right sizes of everything. I couldn't find a Marelon throughull/seacock/tailpipe with the right inside diameter for the raw water intake and ended up going bronze on that one.

[ndutton]

Since the inside is gutted and we have clear access to all the thu-hulls and they are all gate valves, we decided to rebed the fittings and replace all the gate valves. Here is my question. Can I use standard brass plumbing fixtures (1/4 turn ball valves) I can pick up locally and at a lower cost?

Just one observation: Certainly those gate valves were conventional plumbing variety, tapered threads and "non-marine" brass. So how long did they last?

[lat 64]

One way to tell if you might have good silicon bronze or even Everdure(trade name for good marine bronze) is to look at the price. It won't be cheap! A good deal is probably too good to be true. Home Depot and others won't stay in business long if they sell real bronze for brass prices. Brass is good for homes, not boats
My boat is full of this hardware-store junk and I have to start a refit soon or somethings going to sink.

[67c&ccorv]

Just one observation: Certainly those gate valves were conventional plumbing variety, tapered threads and "non-marine" brass. So how long did they last?

AFAIK Neil there were gate valves made to marine standards used on early (1960's) vessels.

Not sure of brand/make etc. but my 1967 C&C Corvette (Hull #29) still has some of her original gate type thru-hull valves that were properly set into the hull with backing plates etc. They are still working well although I will probably start to replace them in the near future.

I will post some pics when I do - keep in mind this is a fresh water boat for her entire lifespan (so far?).

[rigspelt]

During this 1974 C&C 27's refit couple of years ago, we removed what appeared to have been original gate valves. None of the gates were working right, but the throughulls and valve bodies were solid and in excellent shape -- very good quality marine bronze. The wood backing plates were very old but not punky. The valves had all been bonded together with heavy gauge black wire.

[hanleyclifford]

When I acquired by boat she was fitted with high quality bronze gate valves. The thru hulls had backing plates and bronze nuts. Although the materials were good, the installations were defective for reasons already noted. All have been replaced with proper seacocks (bronze). However, some good uses for gate valves remain. One that comes to mind is a shut off near the transom for an exhaust system (but it better be large).