Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 07-02-2016, 10:35   #31
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Holding tank discharge via thru-deck opening

This is what I suggested above. Here it's pumping into a sewer but it could just as easily pump into a container or even overboard.
Attached Thumbnails
Click image for larger version

Name:	Pumpout Composite.jpg
Views:	57
Size:	376.4 KB
ID:	118532  
__________________

__________________
rwidman is offline   Reply With Quote
Old 07-02-2016, 10:56   #32
Registered User

Join Date: Jan 2013
Posts: 203
Re: Holding tank discharge via thru-deck opening

I was showing the picture of them pump as an example of putting slight positive pressure on tanks.

If you read any of this post, you would have seen that I suggested using the pressure from the head to pressurize the holding tank.

This light pressure would only be until the effluent reached the height of the elbow on the pump out port and started down the hose, to a point where the siphon would start.

Once a siphon started, the pressure would be removed and the vents would have to be opened to let air flow in and replace the siphoning effulent.

It would be as simple as flushing my Vacuflush head, with the water supply off, after attaching the hose and holding a gloved finger over the tank vent, until the flow started.
__________________

__________________
twinboat is offline   Reply With Quote
Old 07-02-2016, 10:59   #33
Senior Cruiser
 
senormechanico's Avatar

Cruisers Forum Supporter

Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 5,827
Re: Holding tank discharge via thru-deck opening

Quote:
Originally Posted by twinboat View Post
I suppose that could happen.

I do have a Vacuflush system so whatever makes it to the tank is mashed up thru the bowl and then the piston pump first.

If I try this, I will check the clamps on the discharge hose.

All of my tank fittings go in the top of the tank. At least it won't drain out if a hose comes off.
Be sure and take a video when you do.

Post it on Youtube and if your system blows apart you'll get millions of views !!
__________________
Memento,homo, quia pulvis es, et in pulverem reverteris.
senormechanico is offline   Reply With Quote
Old 07-02-2016, 10:59   #34
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank discharge via thru-deck opening

Give it a try and let us know how it works!
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Old 07-02-2016, 15:29   #35
Registered User
 
sanibel sailor's Avatar

Join Date: Feb 2013
Location: Sanibel FL
Boat: 1979 Bristol 35.5 CB
Posts: 978
Re: Holding tank discharge via thru-deck opening

COUSIN EDDIE !!!!!
__________________
John Churchill Sanibel FL
NURDLE, 1979 Bristol 35.5 CB
sanibel sailor is offline   Reply With Quote
Old 07-02-2016, 16:07   #36
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank discharge via thru-deck opening

In the late '70s or early '80s,just as holding tanks began to be required, Jabsco came up with a combination pumpout/discharge deckplate that had two holes in it--a 1.5" pumpout connection and a 1" hole for overboard discharge...the idea being, the macerator would shoot the tank contents out that hole. I've actually run across two boats on which they'd been installed..a sailboat with it in the side deck and a Grand Banks trawler with it in the side of the hull...neither still in use, neither owner could figure out what it was. I found out from someone who'd worked at Jabsco when they came up with this idea. He told me, "One of the reasons the impeller discharge pumps have a 1-1/2" threaded end is because the original thought was that you could screw that in to discharge though the deck plate, but it was never adopted because of the mess issue. There were a number of blow up disasters trying to pump through the deck discharge plate." He confessed that a couple of tests when that side of the boat was to windward weren't too successful either!
Attached Images
 
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Old 07-02-2016, 17:11   #37
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Holding tank discharge via thru-deck opening

You really really don't want to pressurize a holding tank. Physic's is a bitch.

First a holding tank and really the entire sanitary system is not designed for pressure, at all. To lift a liquid up 6 feet in a 1-1/2" hose will take about 4.5 psig. psig= pounds per square inch gauge. Hardly anything right. Hold that thought.

Lets say you have a 20"x20"X20: holding tank. At 4.5 psig, one wall would have a force of 1800 pounds trying to push it out. Same for the other 5 sides too. If your holding tank has a longer side, say 30 inches, then that side would have a force of 2700 pounds against it. Something will give and when it does, it will not be pretty.

To quote, Spengler from Ghostbusters, "It would be bad".

Don't go there.

If you try it, please put the seat down first. You'll be slightly happier for that.
__________________
sailorchic34 is offline   Reply With Quote
Old 07-02-2016, 20:46   #38
Registered User

Join Date: Jan 2013
Posts: 203
Re: Holding tank discharge via thru-deck opening

Quote:
Originally Posted by sailorchic34 View Post
You really really don't want to pressurize a holding tank. Physic's is a bitch.

First a holding tank and really the entire sanitary system is not designed for pressure, at all. To lift a liquid up 6 feet in a 1-1/2" hose will take about 4.5 psig. psig= pounds per square inch gauge. Hardly anything right. Hold that thought.

Lets say you have a 20"x20"X20: holding tank. At 4.5 psig, one wall would have a force of 1800 pounds trying to push it out. Same for the other 5 sides too. If your holding tank has a longer side, say 30 inches, then that side would have a force of 2700 pounds against it. Something will give and when it does, it will not be pretty.

To quote, Spengler from Ghostbusters, "It would be bad".

Don't go there.

If you try it, please put the seat down first. You'll be slightly happier for that.

At last, someone with some convincing data as to why it may not work.

I was never satisfied with " You just can't do that".

The top of my tank is about 20 inchs below where the elbow in the discharge fitting would be. If I was in international waters and had a full waist tank and no pump out avalable, I may try it.

Thanks, it was an interesting debate.
__________________
twinboat is offline   Reply With Quote
Old 07-02-2016, 21:51   #39
Registered User
 
ontherocks83's Avatar

Join Date: Aug 2013
Location: Massachusetts
Boat: Checkmate Strobe 201
Posts: 1,593
Re: Holding tank discharge via thru-deck opening

Quote:
Originally Posted by reed1v View Post
Be on the lookout for periscopes however. My naked wife found that out to her embarrassment.
I hope that is a true story because that is precious! Did she wave and laugh along or get weirded out? I personally would have stripped naked next to her and started doing the truffle shuffle at the periscope just as a goof.
__________________
-Si Vis Pacem Para Bellum
-Molon Labe
ontherocks83 is offline   Reply With Quote
Old 08-02-2016, 03:18   #40
Registered User

Join Date: Jun 2015
Posts: 315
Re: Holding tank discharge via thru-deck opening

Made my own pump out last year using a manual bilge pump a plumbing elbow and some pipe. The elbow is 1 1/4, threads right into the deck plate, same thread, homedepot plumbing section provided all the new parts.
Pumps into a 45 gallon plastic barrel which then gets pumped into a septic tank.
Works on vacuum, slick setup cost me about 20$ in new parts.
Saves me a trip through the Murray Canal everytime I need to empty the tank, was a near full day excursion.
I mix a bucket of bleach and water for cleanup whenever I pump out anyway, pump some through the bilge pump and hose - clean enough.
Could easily use the same rig to pump out offshore, just no barrel attached to the discharge hose.

http://www.tank-depot.com/product.aspx?id=755
Homemade version of this
__________________
Siberianhusky is offline   Reply With Quote
Old 08-02-2016, 04:07   #41
Registered User

Join Date: Aug 2007
Location: Adelaide, South Australia, sailing in the Med.
Boat: Beneteau, Oceanis 50
Posts: 426
Re: Holding tank discharge via thru-deck opening

[QUOTE=Pizzazz;2035481]I am thinking of removing the thru-hull discharge of my holding tank and pumping out my holding tank only thru-deck.

On my Hunter 31 the waste from the toilet goes directly to the holding tank. The holding tank discharge hose goes to a Y-valve, one end goes to the thru-deck pumpout port, the other goes through a Whale pump, a siphon, and then to the thru-hull valve.

QUOTE]

Is your holding tank below water level? If not, this is a complicated way of doing it. Much simpler to have the macerator pump (or manual pump) at the base of the toilet, pump up to the top of the tank. Then to discharge, the tank is either evacuated through the normal deck fitting / shore pump-out, or a simple ball valve at the through-hull is opened and the tank empties via gravity. No 'Y' valves, and only the single through-hull ball valve. The other plus, is that with the rush of liquid out of the tank when emptying via gravity (when well off-shore of course), any sludge at the bottom of the tank is swept out also, meaning the tank is much cleaner - especially if you give it a good flush regularly.

As to your suggestion, I share the other contributors views - messy, not sanitary, and time-consuming.

I hope that helps.
__________________
David B is offline   Reply With Quote
Old 08-02-2016, 04:17   #42
Registered User
 
sanibel sailor's Avatar

Join Date: Feb 2013
Location: Sanibel FL
Boat: 1979 Bristol 35.5 CB
Posts: 978
Re: Holding tank discharge via thru-deck opening

most tanks have the egress at the top, not bottom, just like a fuel tank, for the same reasons. Gravity would require a bottom drain
__________________
John Churchill Sanibel FL
NURDLE, 1979 Bristol 35.5 CB
sanibel sailor is offline   Reply With Quote
Old 08-02-2016, 05:16   #43
Registered User

Join Date: Aug 2007
Location: Adelaide, South Australia, sailing in the Med.
Boat: Beneteau, Oceanis 50
Posts: 426
Re: Holding tank discharge via thru-deck opening

Yes - a large outlet at the bottom of the tank for gravity discharge. Works very well.
__________________
David B is offline   Reply With Quote
Old 08-02-2016, 07:44   #44
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,649
Re: Holding tank discharge via thru-deck opening

Quote:
Originally Posted by sanibel sailor View Post
most tanks have the egress at the top, not bottom...
No, most have the outlet at the bottom, not the top.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is online now   Reply With Quote
Old 08-02-2016, 09:26   #45
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank discharge via thru-deck opening

...Much simpler to have the macerator pump (or manual pump) at the base of the toilet, pump up to the top of the tank....

Adding a macerator or manual pump to a toilet discharge does anything BUT simplify the system...starting with, it becomes a blockage in the toilet discharge line if it isn't operating simultaneously with the toilet's pump. If your toilet--manual OR electric--can't lift bowl contents up to 4", rebuild or replace the toilet...they're all rated to lift at least that high.
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Reply

Tags
deck, holding tank

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Is Gravity Discharge Possible from a Blackwater Holding Tank ? Unicorn Plumbing Systems and Fixtures 27 02-09-2014 07:08
Holding tank and thru-hull protocols. Robin3 Plumbing Systems and Fixtures 16 11-05-2014 09:53
holding tank discharge questions again! Robin3 Plumbing Systems and Fixtures 18 25-03-2014 16:15
Holding Tank Holding Tank Leaff Construction, Maintenance & Refit 17 01-07-2012 06:12
Gravity-Out Holding Tank Thru-Hull Size opusnz Plumbing Systems and Fixtures 4 18-05-2010 21:27



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:54.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.