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Old 28-10-2010, 04:59   #1
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1-1/4 Inch Waste Outlet Through-Hull

I recently removed the original bronze flush-mounted waste outlet through-hull from my 1975 Ericson 25. It is 1-1/4. I would like to replace it with a 1-1/4 bronze Groco flush-mounted through-hull. It would be preferable to have a 1-1/2 inch though-hull, but I would like to avoid having to enlarge the existing hole and especially the existing counter-sunk socket in the hull.

I plan to place a 1-1/4 inch Groco flanged adaptor on top of the through-hull, and then a 1-1/4 inch Groco in-line ball valve on top of it. The ball valve would be topped by a Groco FULL FLOW pipe-hose adaptor. This full flow adaptor will allow me to use a standard 1-1/2 inch ID sanitation hose to make the connection with the toilet, a Raritan, PHII.

Have others met with success using a similar 1-1/4 inch set up?

Thanks for your help,
Roscoe
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Old 28-10-2010, 06:46   #2
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The Groco full flow tailpiece (1 1/4 NPT x 1 1/2) worked fine for me.
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Old 28-10-2010, 07:36   #3
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Thanks Don,

Yes, according to my calculations, even if you use a 1-1/2 inch through-hull, you still have sections in your system that measure 1-1/4 inch. I'm thinking of the barbed outlet on the toilet and also the barbed tailpiece. These are the bottlenecks, so to speak, in a 1-1/2 inch through-hull/seacock set up.

Thus, a 1-1/4 inch set-up has only one more bottleneck - the through-hull/seacock.

Does that sound right?

Thanks,
Roscoe
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Old 28-10-2010, 14:55   #4
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Hi Roscoe,

Big is good - do not even waste the effort of a blink at installing a larger thru-hull. And just because you removed a 1.25" thru-hull does not mean that the new Groco thru-hull will fit! Last year I replaced my boat's nine Groco knock-off rubber plug sea cocks and their thru-hulls, ranging from 0.75" to 1.5", with the Real Deal, and the new Groco thru-hulls did not fit the existing flush molded-in holes.

Here are pictures and commentary from my galley sink thru-hull, which is 1.25". Although I retained the 1.25" hose fitting because that is what is on my galley sinks, it is the same process to install a larger thru-hull or use a full-flow hose adapter.

Galley sea cock - the beginning:

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After tapping through the very difficult to remove thru-hull - note the detached epoxy barrier coat (gray).

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Factory fiberglass molded-in for the thruhull.

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The new Groco thru-hull did not fit the old 1.25" hole - I inserted the thru-hull and drew a line around it with an indelible marker.

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I used a hammer and common wood chisel to tap . tap . tap away the fiberglass until the new Groco thru-hull fit flush.

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I followed instructions from a (then) recent issue of Professional Boatbuilder to install the new seacocks and thru-hulls.

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After bottom paint.

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Inside - note that I did not slather the entire sea cock with sealant where it mates with the backing plate - only where the mounting bolts are.

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My reasoning for this is that if the thru-hull leaks I want to know about that - so if water is getting through between the thruhull and hull, it should seep out between the seacock and backing plate - the bolts into the backing plate are isolated from the leak with sealant - protecting the backing plate wood from rot.

DO NOT USE 5200 - we all want these installations to be permanent, but if there is a leak you need to remove the mess and fix it! 5200 makes this a *difficult* thing to do.

My bilge pump thruhull was 0.75", but when I removed it from the hull the fiberglass was shattered around the thruhull from hitting a dock or something, and it was very easy to chip out the broken fiberglass to size the hole flush for a 1" thru-hull. I installed a Groco Full-Flow hose adaptor on the ball valve, which meant that I could use a 1.25" hose from the bilge pump - no problemo whatsoever.

Do not hesitate to call Groco with your questions - ask for Patrick - he has been working there since Groco made the ruber plug seacocks, and can answer any of your questions.
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Old 28-10-2010, 16:44   #5
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Hello ShipShape,

Thank you for these very helpful pictures. The 1-1/4 Groco flush mount through-hull has almost identical dimensions to the old one that I pulled. This is one reason why I'm in favor of sticking with the 1-1/4 inch size. The Groco 1-1/2 inch flush mount is said by the Groco catalog to have a 3.2 inch flange. My old flange measures 3 inches. If I go with the Groco 1-1/2 inch through-hull I'll need to enlarge the hole by about 3/16 inch. Your technique for enlarging the hole seemed to work fairly easily. One thing that has been holding me back is the fact that the existing hole appears to have some sort of inner liner. Here's a picture of it. The green is just left over sealant. It's the white ring that I'm talking about. Have you seen anything like this before?

Thanks,
Roscoe
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Old 29-10-2010, 07:32   #6
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Your picture is too far away to really see anything other than the area is white, but given how fiberglass boats are laid-up it is probably gel coat.

In the sixth pic above you can see the layers start with the red anti-fouling paint, next is a gray epoxy barrier coat, then under that it is a thin light blue layer on top of white - this is the gel coat that was applied onto the mold before the fiberglass. Then there is a dark blue paint(?) between the gel coat and the start of the fiberglass layup - I haven't figured that one out yet since its use around the boat has been inconsistent.

Gel coat is an important barrier between the fiberglass and water, so if it is damaged you need to thoroughly paint over the fiberglass with epoxy. As you can see, I chipped away some of the gel coat when I enlarged the hole. I made backing plates from 3/4" marine plywood, and saturated them with epoxy before mounting them. The hull is curved, and the fiberglass inside the hull was very uneven around the thruhull opening(s), so by using a backing plate I not only had a flat mounting surface for the seacock, I effectively more than doubled the hull thickness at the thruhull - in the end it did not matter one bit that I had chipped away any of the hull.

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This shows the backing plate mounted to the hull - there is a good bed of thickened epoxy between the backing plate and the hull, and when the epoxy had set enough to hold the backing plate in place, but not fully cured, I painted the backing plate and entire area through and outside the hull with un-thickened epoxy ... then painted it all again before that layer of epoxy fully cured. There is a Very decent layer of epoxy between the exposed fiberglass and the sealant for the thruhull.

If you follow the same procedure you will be fine, and even if you prefer to preserve the original gel coat under the thruhull flange, it is a good idea to paint on a protective layer of epoxy anyway when you mount the backing plate. Just remember to wash off the wax and sand it a little before mounting the thruhull.
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Old 29-10-2010, 07:39   #7
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I needed a bend right there at the seacock so used a 1-1/4" street elbow with a 1-1/2" hose to 1-1/4" threaded reducer in the street el. Works fine for me.
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Old 29-10-2010, 08:55   #8
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Im curious what people are using for a backing plate these days and how to properly cut and prepare it?
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Old 29-10-2010, 09:08   #9
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SaltMonkey, we actually prefer to use Starboard. You really can't get any sealant to stick to the Starboard, however we want it sealed from the outside anyway for the same reasons ShipShape mentions in an earlier post. It makes a nice clean installation. We are currently planning on replacing the last three of our 30 year old seacocks this winter while the boat is hauled. We have added a new one for the generator intake and all were done with Starboard. A year and a half and about a thousand miles of cruising and no problems. Here is an example, http://tinyurl.com/3y7z4r9 . Chuck
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Old 29-10-2010, 16:29   #10
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Thought everyone would be interested to hear this. I called Raritan today to ask them what they thought about me using a 1-1/4 inch through-hull with the PHII. I spoke first with the customer service manager at the New Jersey home office. He said that I could use either a 1-1/4 or a 1-1/2 seacock/through-hull. Wanting a second opinion, I called the Raritan sales and service center in Ft. Lauderdale, and I spoke with one of the service people. He said that I could use either a 1-1/4 or a 1-1/2. He added that the toilet would flush even with a 1 inch through-hull. I was really surprised by this statement. I looked at some 1 inch tail pipes the other day. Can't imagine trying to flush anything other than waste of the liquid variety through a pipe that size.

ShipShape, I must say that I still lean towards your advice of going with a 1-1/2 seacock/through-hull. Seems that having the largest opening possible at the exit point in the system would aid tremendously in the flushing, despite the fact that there would still be unavoidable 1-1/4 inch bottle necks, both at the toilet outlet/sanitation hose joint and at the sanitation hose/tailpipe joint.
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Old 29-10-2010, 18:24   #11
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Quote:
Originally Posted by davisr View Post
going with a 1-1/2 seacock/through-hull. Seems that having the largest opening possible at the exit point in the system would aid tremendously in the flushing, despite the fact that there would still be unavoidable 1-1/4 inch bottle necks,.
Yup, but if you are out at sea and have a clog you'll know it isn't going to be at the thruhull, and if it is an emergency you can close the seacock and tend to it.

BTW, I also have a Raritan PHII, I named it Fussy F*ck and wrote a limerick for it:

Oh Mr. Crapper,
NOW what's the matter?!
Fun it's not much
The stink, slime and such
Ahh, trouble's with yer flapper.

Fussy has a 1.5" outlet - Raritan must have changed the design over the past two years. Do NOT use the Groco vented loop - the inside is rough and it gets clogged - use a Marelon one. It is also much easier (aka, much less worse ) to remove the little rubber vent thingy to clean it than it is to clean the Groco vent.
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Old 30-10-2010, 07:11   #12
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Considering that every time you put your 1 1/2" hose over a barbed fitting the diameter necks down to 1 1/4", you certainly don't need to go up a size on the through-hull. After all, everything that goes down the hose had to come through the joker valve.

However, I would definitely be leery about going down to 1". At one point my holding tank was emptied by a macerator pump which had a 1" outlet. When I gave up on replacing the macerator pump every year or so and installed a manual diaphragm pump, I got lazy and left the 1" plumbing on the outlet. After one SERIOUS blockage at the point where things necked down to 1", I replaced everything with 1 1/2" plumbing (to the 1 1/4 through-hull), and have been problem free for 10 years.
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Old 30-10-2010, 15:56   #13
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Don,

It sounds like you always pump directly to the holding tank, where the waste has a chance to disintegrate somewhat before you pump it out manually. Do you ever pump directly overboard from the toilet itself through that 1-1/4 through-hull?

Thanks,
Roscoe
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