Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 06-04-2016, 07:05   #1
Registered User

Join Date: Mar 2011
Location: fl- various marinas
Boat: morgan O/I 33' sloop
Posts: 528
Holding tank capacity

My plastic holding tank is a hair over 2 CF so it ought to hold 15 gallons. Yet on pump outs it appears to consistently yield 10 gal even when filled with a hose. Does it make any sense that sludge could take up 1/3-rd of the capacity? How about the theory that outlet pipe projects 4" above the bottom of the tank (12" high)? Would there be any design reason to do that?
Assuming sludge, any suggestions on chemicals or additives to help dissolve it ?

Dave22q is offline   Reply With Quote
Old 06-04-2016, 08:23   #2
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 11,668
Re: Holding tank capacity

I have used dishwashing detergent and a few gallons of water and gone for a sail on a windy day, then straight to the pump out.
Dishwashing detergent as it doesn't make many suds, and it's cheap.

I don't understand why your outlet hose wouldn't be on the bottom, perhaps there is a sort of dip tube? Have to take the hose off and look I'm afraid, but that would tell you.

a64pilot is offline   Reply With Quote
Old 06-04-2016, 11:40   #3
Registered User
denverd0n's Avatar

Join Date: Jun 2008
Location: Tampa, FL
Posts: 3,475
Images: 6
Re: Holding tank capacity

I would begin by asking, how certain are you that it holds 2 CF? Could it be a non-rectangular shape, with angled sides or cutouts where you cannot see them, and so you are misjudging the volume?
denverd0n is offline   Reply With Quote
Old 06-04-2016, 14:28   #4
Registered User
ranger42c's Avatar

Join Date: Aug 2012
Location: Maryland, USA
Boat: 42' Sportfish
Posts: 2,278
Re: Holding tank capacity

Our tank nominally holds 40 gallons... but the real limit is about 24 gallons... partly due to tank measurements and wall thicknesses (40 was optimistic in the first place) and partly due to the location of the inlet hose from the toilet (about 3" lower than the top of the tank).

You might check both wall thickness (to see if it matters) and the inlet hose location.

OTOH, I'd guess could be complicated by sludge build-up, too.

Selby Bay, South River, Chesapeake Bay, USA.
ranger42c is offline   Reply With Quote

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
Capacity of holding tanks and water tanks Sailsarefull Plumbing Systems and Fixtures 103 22-05-2015 07:45
Holding Tank Holding Tank Leaff Construction, Maintenance & Refit 17 01-07-2012 05:12

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 18:06.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.