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Holding tank Vent locations

Bob S

.
Sep 27, 2007
1,552
Beneteau 393 New Bedford, MA
I going to add 1" vents to my holding tanks. There are two heads in the two cabin version of the 393. I'm not concerned about the aft head but the forward one is in the V behind the anchor locker. I want to keep the vent lines as short and high as possible. With the mushroom thru hulls this far forward should I be concerned about sea water migrating into the holding tank? I'd like to avoid a clam shell fitting over the mushroom, it would have to be rather large.
 

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Bob S

.
Sep 27, 2007
1,552
Beneteau 393 New Bedford, MA
Hi Peggie,

They are located at the top of the tanks. I haven't traced their paths out the sides but I was going to keep the old vents and add new ones per your repeated advise :)
I have Uniseals. Are two vents better than one?
 

Bob S

.
Sep 27, 2007
1,552
Beneteau 393 New Bedford, MA
Both tanks are above the waterline. The tops are about a foot below the deck.
 
Dec 2, 1997
7,711
- - LIttle Rock
(vents) are located at the top of the tanks. I haven't traced their paths out the sides but I was going to keep the old vents and add new ones per your repeated advise :)
The entire boating world has attributed the need for 2 vents in all holding tanks to me... but I've never said that. That's not the only thing...I see posts all time from people doing who've claimed to follow my advice but done exactly the opposite. :banghead:
There are SOME situation in which two vents are needed, but yours--at least the forward tank anyway--isn't one of 'em.... the aft tank may be a different story. It won't hurt to keep the existing vent in addition to a new one, but a new 1" vent off a fitting ON the top of the tank at the bow end of it, run forward to an open "bulkhead" thru-hull that's about 3' aft of the stem about a foot below the toe rail will do the job beautifully. And unless you spend a day or more in seas that keep your decks awash, you won't take on any water via the vent. If you think that's likely to happen, a shutoff valve in the vent line solves that problem.
Because every installation is unique to some degree, we prob'ly should work out the details one-on-one instead of in open discussion forum 'cuz not everything we'll spec out may work on every boat. So send me a PM if you're up for that and I'll be glad to help you get it all right the FIRST time!
--Peggie
 

Bob S

.
Sep 27, 2007
1,552
Beneteau 393 New Bedford, MA
The entire boating world has attributed the need for 2 vents in all holding tanks to me... but I've never said that.
Peggie,
You don't know how much you are appreciated, not by just me, but by everyone on this forum. You're an amazing asset to all of us....Thank you!!

I purchased your book a long time ago and I've read it many times. I've lurked in this forum for better part of a decade. I've learned a lot just by that. I have read many of your replies to many posters and I have seen how misinterpreted you have been. I think it was a Roger Long's post before he set out on his adventure that I first saw a two vent option being discussed. That is not why I was thinking of doing it. There isn't a lot of room atop the holding tank and the deck. I will need a right angle drill to do it. The existing vent has a welded vent opening and if I hole saw it out it might not be a smooth fit for the Uniseal. I'm not sure if that would compromise the seal. I was going to cut it adjacent to the existing vent were it is smooth. I just figured it wouldn't hurt having two. I'm doing this now because I'm getting a little back pressure and I figure it's either a blocked vent which is too small to begin with or the hoses have built up too much crud and are now suffering from hardening of the arteries :(.
unless you spend a day or more in seas that keep your decks awash, you won't take on any water via the vent
That answers my question:).
Over the next winter layup I plan on changing out all my hoses and replacing both heads with new Raritans. When I do I will have lots of questions.
 
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Jan 11, 2014
5,764
Sabre 362 113 Fair Haven, NY
There isn't a lot of room atop the holding tank and the deck. I will need a right angle drill to do it.
Get one of these right angle drill adapters Dewalt makes one. Inexpensive and they work.

The existing vent has a welded vent opening and if I hole saw it out it might not be a smooth fit for the Uniseal.
There will be some tear out and rough edges. A little work with some sandpaper will get rid of the jagged edges. Sand across the top and bottom of the hole, not. in the hole so the diameter is not enlarged.

It does take an act of faith to install the first Uniseal, however they really do work.
 
Dec 2, 1997
7,711
- - LIttle Rock
Over the next winter layup I plan on changing out all my hoses and replacing both heads with new Raritans.
Meanwhile, cure the back pressure problem by doing 3 things: 1. Clear any vent blockage. Use a screwdriver blade, ice pick--whatever works to scrape out the vent thru-hull. If that doesn't clear the vent, you may have to scrape out the other end of the vent line--that end of the hose and the vent fitting on the tank. Open the pumpout fitting cap to relieve any pressure BEFORE removing any hoses! 2. Use about a 15% solution of muriatic (available from any hardware store) to dissolve any buildup in the toilet discharge hose. Pour it down the toilet and be sure to CAREFULLY followALL directions for handling and using muriatic acid. 3. Lube the toilet.
You said you bought my book years ago...you might want to pick up a copy of the "new revised updated and expanded 2nd edition" that was released in Feb of '16. If you want to see just how much has been updated and added, check out the Table of Contents. If you want another hard copy, please buy it from sbo.com (see link in my signature)...Amazon is the only source for the Kindle e-book version.
--Peggie
 

Bob S

.
Sep 27, 2007
1,552
Beneteau 393 New Bedford, MA
Use about a 15% solution of muriatic (available from any hardware store) to dissolve any buildup in the toilet discharge hose. Pour it down the toilet and be sure to CAREFULLY followALL directions for handling and using muriatic acid. 3. Lube the toilet.
What effect if any does this have on a joker valve or wye valve?
 
Jan 11, 2014
5,764
Sabre 362 113 Fair Haven, NY
What effect if any does this have on a joker valve or wye valve?
It should have no negative effect on the Y-valve and probably not the joker valve. Since a joker valve should be replaced every year, running the acid through the system prior to replacing the joker valve would alleviate that issue.

While it is more work, removing the Y-valve from the boat and cleaning it at home is way more fun!

Before:
IMG_0862.jpg


During:


After:

IMG_0947.jpg
 
Dec 2, 1997
7,711
- - LIttle Rock
Maybe a dumb idea, maybe not... Dave's in Fair Haven NY, which is on Lake Ontario about 50 miles east of Rochester NY. There are several New Bedfords...depending on which one is your home, you may or may not be too far apart to talk him into helping you with this project. It may depend on how much you'd be willing to spend on the most expensive bottle of the adult beverage of his choice to woo him with. :biggrin:
--Peggie
 
Jan 11, 2014
5,764
Sabre 362 113 Fair Haven, NY
Maybe a dumb idea, maybe not... Dave's in Fair Haven NY, which is on Lake Ontario about 50 miles east of Rochester NY. There are several New Bedfords...depending on which one is your home, you may or may not be too far apart to talk him into helping you with this project. It may depend on how much you'd be willing to spend on the most expensive bottle of the adult beverage of his choice to woo him with. :biggrin:
--Peggie
I don't think there are enough bottles of a vintage adult beverage to woo me into traveling to New Bedford MA to wrestle with smelly sanitation hoses. All of my hoses are less than 5 years old and I'm thinking the next owner can deal with them. :biggrin:

When I took a look at the Y-Valve and saw the calcium build up I was quite surprised. My boat has lived most of its life in fresh water and the overboard discharge has been disabled. It did spend one or two years in salt water in the Caribbean early in its life. That seems like a lot of crud to build up in 2 years and I'm not surprised that the prior owner didn't clean it, cause he didn't clean much on the boat.

It was kind of fun making calcium chloride and hydrogen gas in the back yard. Reminded me of the fun days in the Chemistry Lab when I thought I wanted to be a chemist.
 
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Dec 2, 1997
7,711
- - LIttle Rock
Bob doesn't indicate which state his home is in and Google Maps came up with no fewer than 3 New Bedfords including one in NY.

You'd be amazed at how quickly sea water minerals can clog a hose, especially in warm waters. I posted this photo to another thread just a few days ago....what you're seeing took only few months.

--Peggie
 

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Jun 5, 2010
990
Hunter 25 Burlington NJ
The entire boating world has attributed the need for 2 vents in all holding tanks to me... but I've never said that. That's not the only thing...I see posts all time from people doing who've claimed to follow my advice but done exactly the opposite. :banghead:
Hey! --I've been repeating that from you for years to everyone who ever asks.

Actually what I think you said, Peggie, was that in sailboats, it's a very good idea to have two, one on each side, since (as you said) the boat spends so much time with wind on the beam that the air flow helps very much in removing stink and aiding aerobic decomposition.

I installed two vents on my tank (which is a rigid rectangle under the V-berth), one each side, each 3/4" PVC (to fit the fitting on the tank) leading immediately beneath the V-berth plywood, laterally towards the hull, ascending outboard almost to the gunwale from where just a short 90-degree bend of 3/4" sani hose connects to the inside of the vent fitting. Rigid PVC tubing = no sags; theoretically complete evacuation of tubing, depending on heel angle. Tank vents = SS through-hull fittings; no screens and so admitting maximum of air.

I tend to advocate a 'complete' periodic flush-out of the holding tank including squirting dockside water down the vent lines before re-emptying the tank. Tends to eliminate places where gook can lodge.
Also I tend to advocate ONLY nitrator (essentially fertilizer) as a tank additive. In my experience anything perfumed with alcohol-based products just adds smell rather than eliminating it.

I'll be interested to hear your thoughts, Peggie.
 
Dec 2, 1997
7,711
- - LIttle Rock
Actually what I think you said, Peggie, was that in sailboats, it's a very good idea to have two, one on each side, since (as you said) the boat spends so much time with wind on the beam that the air flow helps very much in removing stink and aiding aerobic decomposition.
Nope...I've never said that either. But since doing anything that increases the amount of oxygen in the tank can only help, it's ok with me if you want to have two vents.
Replacing the "vent" thru-hull with an open bulkhead or "mushroom" fitting is often all that's needed. That has another advantage: it makes it possible to stick hose nozzle against it to backflush the vent line every time you wash the boat and/or pump out. And I've also always recommended thoroughly flushing out the tank 2-3 x/season to eliminate any sludge.
As for tank products, Odorlos (nitrate product) is a very good one. However, there's an even better one that is neither bio-active nor nitrate, but a propriety blend of enviro-friendly ingredients that not only does an outstanding job of preventing odor even in marginally oxygenated tanks, but also "digests" sludge: No-Flex Digestor Noflex Digestor Everyone who uses it raves about it.

--Peggie
 
Last edited:
Jun 5, 2010
990
Hunter 25 Burlington NJ
Odorlos (nitrate product) is a very good one. However, there's an even better one that is neither bio-active nor nitrate, but a propriety blend of enviro-friendly ingredients that not only does an outstanding job of preventing odor even in marginally oxygenated tanks, but also "digests" sludge: No-Flex Digestor Noflex Digestor Everyone who uses it raves about it.

--Peggie
Thanks for that, Peggie. I sell a lot of Odolos but have never heard of No-Flex and shall try it soon.

I've long advocated (as I said in my other post) backflushing the system through the vents, but more than 1-3x /season - more like every time you empty the tank at the dock. Also by shooting dockside water down the deck plate as well. What can it hurt?
 

Bob S

.
Sep 27, 2007
1,552
Beneteau 393 New Bedford, MA
As for tank products, Odorlos (nitrate product) is a very good one. However, there's an even better one that is neither bio-active nor nitrate, but a propriety blend of enviro-friendly ingredients that not only does an outstanding job of preventing odor even in marginally oxygenated tanks, but also "digests" sludge: No-Flex Digestor Noflex Digestor Everyone who uses it raves about it.
Hi Peggy,
I'm am currently using the Noflex Digestor but still have a gallon of Oderlos. Would adding a little Oderlos to the tank that I'm currently using Noflex hurt or would it be better to finish the gallon first then switch back to the Noflex? Also, I have the CP and K.O. from Raritan. Is there any concerns using them with the Noflex as well?
 
Jan 22, 2008
7,632
Beneteau 323 Annapolis MD
...You said you bought my book years ago...you might want to pick up a copy of the "new revised updated and expanded 2nd edition" that was released in Feb of '16. If you want to see just how much has been updated and added, check out the Table of Contents.
--Peggie
The book was a great idea. The kiss using hot pink lipstick was a nice touch, too. However, it seems someone must have pilfered the centerfold ... :banghead:
 
Dec 2, 1997
7,711
- - LIttle Rock
Live bacteria is the active ingredient in both K.O. and C.P....nitrates is the active ingredient in Odorlos so it can't hurt to mix 'em with each other and/or NoFlex. But since NoFlex doesn't need any help, why not donate the Odorlos and KO to a friend who obviously needs it. Since KO needs more oxygen than many tank vents provide, I'd tell the friend to combine 'em.

But why would you want get rid of C.P.? It's not a tank treatment. Raritan only markets it as a toilet bowl cleaner--and it's very good one--but it also happens to be the best sump and drain cleaner on the planet! A couple of ounces once a week or so down the shower drain into a sump that's about 1/3 full of clean water when it can remain at least overnight will keep it clean and odor free without any manual labor. An ounce in a slow smelly sink drain when it can stand at least overnight (close the seacock first, then add the CP and fill the drain with clean water) will leave it running free and odor free.

--Peggie
 
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