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Groco Bronze Thru-Hull Fittings are threaded with NPS (straight) male pipe thread, and are for use with Groco Seacocks or with any product with straight female pipe thread.
The use of these fittings on products with NPT (tapered) pipe thread is recommended only for low pressure applications, and then only with a generous application of pipe sealant or PTFE thread tape.
Groco Bronze Thru-Hull Fittings are the best choice for below-the-waterline use. They are supplied complete with a bronze locknut with bonding screw or they may be threaded directly into a compatible seacock.
$18.54
$23.69
$28.94
$46.39
$53.56
$83.07
$182.88
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BRAND:
Groco
Material:
Bronze
Metal:
Bronze
Type:
Thru-Hulls
Questions & Answers about Groco Bronze Thru-Hull Fittings:
2012-09-27A shopper asked: What type of sealant is best for bronze thru hull fittings with a fiberglass hull ???
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2012-09-28ROGER DEMLER: I would guess 5200 but I have a wood boat. I had to make a wrench to reach the nut tru a small hole and several inches of ceiling (hull liner to your chlorox people) and frames. I heated a piece of PVC pipe in the oven (don't recall temperature) and forced in over the nut and let it cool. That took a lot of torque without stripping.
2012-09-29WILLIAM GIBBONS: I am going to use 3M 4200 for all my thru-hull fittings and portholes, all of which I am replacing and re-installing. My hull is 3/4 inch marine plywood covered with fiberglass, a Newporter 40. Wood or fiberglass does not make a difference with regard to the sealant. The main thing is a good backing plate glassed or epoxied in place and thick enough to accept the mounting screws without perforating the hull. There are several on-line instructional videos on installing seacocks. Good luck
2012-09-29RANDALL BRUCKMAN: 3M 5200
2012-09-29DON PETSCH: I believe this is one of the very few applications where 3M 5200 is a good choice.
2012-09-30JON CREHORE: Underwater silicon or poly sulfide caulk will work.
2012-08-03A shopper asked: is bronze thu hull compaible with aluminum hulls?
2012-06-28JUSTIN ROE asked: Is the inner diameter of the 3/4" thru-hull less than or equal to 11/16ths?
I am looking to add threads all the way through the interior of one of
these brass thru-hulls. Specifically, I want to take a thru-hull with
3/'4" NPS threads on the exterior (I'm looking at the TH-750-W), and
add 1/2" NPS threads to the interior. Is there enough material to do this?
I believe the hole needs to be a clean, reamed diameter of 11/16ths
(and not a 64th smaller) to accommodate being tapped with 1/2" NPS
female threads.
Thanks!
Justin Roettger
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2012-06-29RALPH COHEN: I can't answer this absolutely as I have no way to make the measurement and no data sheet. Looking at a dimension table for piping, if the thru-hull is sch 40 or 80 dimensioned, the ID is likely 0.824 or 0.742. Only if its sch 160 (unlikely) would the ID be small enough to work. If you aren't attaching a valve to the end of the thru-hull, then perhaps a coupling and reducing bushing could be obtained. This could be problemmatic as the thru-hull is straight threaded and your plumbing fitting is tapered thread. As I used a valve on my thru-hulls, I had no difficulty attaching whatever fittings I needed and would recommend that as the easiest path forward.
2012-06-29CARL COZZA: specifically i can't say because I got an inch and a quarter fitting. But i can tell you it is thick and robust.
2012-05-22A shopper asked: what is the diameter dimension ID OD ?
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2012-05-23THOMAS FUHS: You don't mention which size Groco Thru-hull fitting you are asking about. In general, thru-hull sizes are the NPS thread size. So, a 3/4" thru-hull will have 3/4" NPS thread size on its body. If you need a specific ID or OD, I suggest looking up NPS thread sizes. For example, a 3/4 NPS will have an OD of 1.05 inches. Hope this helps.
2012-05-23RALPH COHEN: The 1" thru-hull fitting should have an O.D. of 1.315 inches. I am getting this from the ANSI standards. Keep in mind that the thru-hull threading is straight and not tapered like pipe thread. This works fine if threaded into a proper thru-hull valve. I used a Buck Algonquin 1" bronze ball valve to connect to the thru-hull fitting. Using an ordinary hardware store valve will not work. There is a excellent article in Wooden Boat Magazine a few issues back about installing through hulls if you want more information.
I am not sure but I am guessing that I used a 1-3/8 inch hole saw to cut through the hull. I would recommend a trial cut on a scrap to verify that size is large enough.
The I.D. I can not provide as the fitting is not accessible and I have no record. Its going to be close to 1 inch.
Ralph (Zakkendrager on Wooden Boat forum)
2012-05-23MICHAEL THOMAS: Go to groco dot net and you can get the specifics of each fitting dimension.
2012-03-14JAUNITA KERR asked: the hole size is 1-1/8'' and the transom is 2" so will this item fit my boat? hop so
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2012-03-15RALPH COHEN: It depends. If there is a 2" diameter hole in the transom, I would say that a thru-hull with a 1-1/8" diameter is not going to make a good installation. If it were me, I'd plug the 2" diameter hole properly with wood and then bore the proper size hole.
But if you are saying the transom is 2" thick, then a thru-hull fitting of the correct length will work. The hole should be only slightly larger than the fitting. But the fitting needs to be long enough to have a backing block on the inside and to attach the valve with sufficient threads engaged in the valve. Its normal to have to cut the fitting to length.
There was an excellent article on installing thru-hull fittings in the last issue of Wooden Boat magazine.
2012-03-15PAUL HILLE: juanita, depends on which one or size valve. The size hole is for the corresponding fitting. I believe your 2" measure is the thickness??? This is not really related here. Whichever fitting u purchase, they will have a recomendation of hole size to drill. I reccomend u " Compass Marine projects by Maine sail and choose the job for thru hull install, has easy instructions and pictures, good luck...Red
2012-03-16CARL COZZA: I think it is too long, 3".
2011-11-19JOSEPH WOLF asked: is this available in 1" thread with 2-3/4 o.d. flange ?
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2011-11-21PETER GALLOWAY: High quality. No issues.
2011-11-21MICHAEL TAYLOR: Yes I believe they are available in all standard pipe sizes from 3/4" up and with 2-3/4" flange on the 1" thru-hull
2011-11-14RON SAVELL asked: where manufactured ?
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2011-11-14JOE MELLON: It's been a while but I'm pretty sure was manufactured in USA. Don't think it was China.
I was very satisfied with this product.Got a pair of them...one for each side of my boat.
I have a 15 1/2' cedar and oak (I think)] boat built for the Delaware Bay in 1949.
I had to shorten the length of the threaded part as my hull is 7'8s" thick.
The particular manufacturer? Sorry but don't remember.
Good Luck...Joe Mellon
2011-11-15DALE POWELL: Sorry, it's installed in the boat and would be hard to determine origin.
2012-06-20MICHAEL ABBENE: USA
2011-10-14A shopper asked: groco engineer said the first 1/4 inch is a npt thread ? you say nps?
confused
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2011-10-14DENNIS FAIST: The threads on the unit that I received were straight threads - the length of the casting - stopping maybe a 1/4 inch or so from the flange.
2011-10-14DALE NICHOLS: Dear Shopper, these thru-hull fittings state in the description that they are NPS, or straight threads. They are generally used with other NPS fittings but can be used with NPT( tapered) fittings in low pressure applications. In this application, a lot of pipe sealant or PFTE thread tape must be applied to achieve a proper seal.
We used these parts as samples for a plastic molder of parts that our company requires. They are producing NPS plastic fittings for our marine customers.
2011-10-14PETER TOLLINI: Through hulls are always NPS (straight) thread to mate correctly to seacocks. Valves are NPT (tapered) thread, as is the upper thread on a seacock. Some Groco through hulls are "dual thread" in that an NPT valve or adaptor can be used and seat properly, or the fitting can be threaded into a NPS seacock. Groco tech support is awesome and can answer your specific question easily as well as a couple you haven't thought of.
2011-10-14JAMES STUART: I bought a Groco thru hull and installed it in June. The threads on the fitting are not tapered ( like standard pipe fittings are ) so that the nut can be turned onto the male threads to any point and always have equal purchase. If the thru hull fitting did have tapered threads the nut would gradually bind as it moved closer and closer to the flange. This is important so that the thru hull may be used on a wide range of hull thicknesses. I might add that a basin wrench is ideal for tightening the nut if it is in a relatively difficult location.
2011-10-15STEVEN MINNICH II: These fittings are a "combo" thread. The majority of the fitting thread is NPS, though the last 1/2" or so (on mine I ordered) is machine tapered to act as and NPT thread. This allows you to thread a ball valve onto the end of it and get it to seat properly (3/4" +). . .where as if you were to thread a ball valve onto the end of a standard thru-hull, you might get 3-4 turns before it binds up (and is dangerous).
Hope this helps!
2011-10-15TOM GOUDY: the engineer is correct
2011-10-15CHARLES SWANSON: It is threaded in all straight thread. The nut threads all the up, down and off. There is no NPT at all on this part. We were able to create an NPT thread for a hose connector by tapping the thru-hull internally with a suitable NPT tap and handle.
2011-10-16JOSEPH SEXTON: NPT means National Pipe Thread Standard. It is a tappered thread that fits into a tappered plumbing fitting and comes in standard sizes 1/8" 1/4" 3/8" 1/2" 3/4" 1" 11/4" 1 1/2" 2' etc
2011-10-12MICHAEL HYMAN asked: The "HULL" I am going to install this "thru hull " fitting is almost 2 inches thick. What is the length of the thru hull fitting? V/R Michael Hyman
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2011-10-13CHRIS STEVENS: With theWith the nut completely backed off (and half hanging off) there is barely 2 inches, You probably need a longer fitting
2011-10-13TROY KROFT: The thru hull will be more than long enough for your hull. In fact, if you are attaching a seacock to it, you will most likely have to cut it shorter. Hopefully this helps!
2011-10-14CARL COZZA: the fitting is 3 inches long
2011-10-19TIMOTHY FERWERDA: The thru-hull fitting has 2 3/8 inches of thickness between the flanges with a few threads showing past the tightening nut
2011-10-19TIMOTHY FERWERDA: I should mention that the thru-hull I bought was 1 inch
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