Sanitation redesign

[Steven UK]

Originally Posted by Cheechako

Yeah, I made a tall thin one bulkhead mounted in a mechanical closet due to limited room. But the height helped give head for the gravity flow out. It made the hose runs nice and short that way too! The head pumped into the top (not shown)

Cheechako
and that is exactly what i wanted to do see my previous thread on gravity only systems. however life and previous boat owners don't always play along. The Previous Owner added another chainplate and tabbed bulkhead aft of the cap shroud at some point (which i like and wont be changing) but it means i cannot put the tall slip gravity tank behind the toilet against the hull. i could put a 4 gal one up high under the V berth but its very limited capacity.

[Steven UK]

here is a simplified version of my plan that should be easier to decipher, the current installation if far from kosher so i want to make sure i get the new one mostly right.

Peggie i read your book and i understand the limitations of the small tank but it will just be me most of the time... and through various unexpected boat expenses i'll probably be tightening my belt somewhat... i am trying to identify larger tanks that will fit.

Best Regards Steven

hopefully there is a file attached.

[Cheechako]

Originally Posted by peghall

Because the gasses generated by organic matter--even odorless CO2 generated aerobically--are heavier than air...they don't rise in a vertical vent line and ambient air out side doesn't "fall" down one. A 45 degree rise is about as much of a vertical rise that'll allow air exchange to happen.



--Peggie

Ahhh... I see. Wouldn't horizontal clog with...!

[Steven UK]

Originally Posted by Cheechako

Ahhh... I see. Wouldn't horizontal clog with...!

its a 3d system on a 2d communication medium, i will try and design out as many horizontal runs as i can but that is exactly the kind constructive comments i need (tanks to everyone who made them). i currently know just enough to be dangerous.... coming up next is the new propane locker...!

Regards Steven

[kmacdonald]

Originally Posted by peghall

Because the gasses generated by organic matter--even odorless CO2 generated aerobically--are heavier than air...they don't rise in a vertical vent line and ambient air out side doesn't "fall" down one. A 45 degree rise is about as much of a vertical rise that'll allow air exchange to happen.
--Peggie

What happens if air exchange doesn't happen? Is that really a big problem?

[peghall]

NO air exchange to keep tank environment aerobic = smelly gasses out the vent every time the time is flushed.


--Peggie

[kmacdonald]

Originally Posted by peghall

NO air exchange to keep tank environment aerobic = smelly gasses out the vent every time the time is flushed.


--Peggie

Aren't there filters for that? Vent placement could address that issue also.

[Steven UK]

regarding the venting i'm going to follow Peggie's advice because she has given consistently good advice (to my untrained ear at least) so far... after reading the info on aerobic bacteria in Peggie's book i got to thinking how to improve it somewhat. below is a system for using one vent tank bung and two vents that could be fore and aft or port and starboard. i'll be having the tank made to and the bungs fitted by the factory so i'll specify as needed. but the idea is to use air velocity and or pressure differential (same thing in this case) to actively move air. it would be nice if someone made something like this i.e. one hole in the hull and two hoses... oh wait i have a full fabrication shop so i'll just go ahead and make one, i'll let you know how it works.

the diagram if it turned up shows a 'T' fitting and a coaxial vent into the tank.

[kmacdonald]

That should ensure a steady flow of sweet air flow from the holding tank. Great idea!!!!!!!

[peghall]

Filters actually help to create the problem they're sold to solve (if only I could have invented something that does that!) because they impede the free exchange of air through the vent that eliminates the need for the filter.


--Peggie

[peghall]

Steven, two vent lines using the same tank fitting won't work. And with a tank that small you shouldn't need more than one...AND the vent fitting should be on the top of the tank.
I think you and I really should talk before you order anything, 'cuz it appears that you may be trying to waaaay over-engineer something that's actually pretty simple.


--Peggie

[Steven UK]

Originally Posted by peghall

Steven, two vent lines using the same tank fitting won't work. And with a tank that small you shouldn't need more than one...AND the vent fitting should be on the top of the tank.
I think you and I really should talk before you order anything, 'cuz it appears that you may be trying to waaaay over-engineer something that's actually pretty simple.


--Peggie

Peggie
Where did you see a vent line that wasn't on top of the tank?

The diagram that i shared earlier shows two vent lines entering a tank co-axially and the outlets either pointing fore and aft or port and starboard to give a pressure differential thus having one higher pressure than the other thus providing flow of fresh air even if the internal volume of the tank is not changing. this would (hopefully) solve the vertical to 45deg vent line issue. the fancy 'T' fitting was just me thinking about a solution for tanks with single vent line outlets.

disclaimer - just because it makes sense in my head and when i read my own posts does not mean it makes sense to everyone else...

Regards Steven

[newhaul]

Originally Posted by Steven UK

so i just purchased a boat that was built without a holding tank and this is what i came up with as a replacement, design constraints are space and cost.

the boat comes with a defunct vacuflush pump that i am hoping to re-purpose as a overboard pump...

go for it...

Best regards Steven

hopefully there is an image attached...

Steven I was in a similar situation the big difference I see was here to be a liveaboard you need at least a 15 gallon tank. Vice that a compositing head.

Here's what I see a lot of engineering and expense to carry 7 gallons of stinky sludge .
And then there are all of the connections that can and eventually will leak and stink.
Also there are the thru hull fittings .
Not to mention moving your boat to the pump out station ( that is when you can find one)
As a part of the overall planning I would suggest considering a compositing toilet. They eliminate all of the issues you may and eventually will have .
You can even build your own for a few dollars or pounds.

[Steven UK]

Originally Posted by newhaul

Steven I was in a similar situation the big difference I see was here to be a liveaboard you need at least a 15 gallon tank. Vice that a compositing head.

Here's what I see a lot of engineering and expense to carry 7 gallons of stinky sludge .
And then there are all of the connections that can and eventually will leak and stink.
Also there are the thru hull fittings .
Not to mention moving your boat to the pump out station ( that is when you can find one)
As a part of the overall planning I would suggest considering a compositing toilet. They eliminate all of the issues you may and eventually will have .
You can even build your own for a few dollars or pounds.

Newhaul
This thought has been in the back of my head... excuse the pun.

i'm not sure what the hang up is but i have a reluctance to throw out the existing equipment and i'm worried guests will freak out a little... to be honest i have never seen a composter first hand.

let me sleep on it...

Regards Steven

[newhaul]

Originally Posted by Steven UK

Newhaul
This thought has been in the back of my head... excuse the pun.

i'm not sure what the hang up is but i have a reluctance to throw out the existing equipment and i'm worried guests will freak out a little... to be honest i have never seen a composter first hand.

let me sleep on it...

Regards Steven

Steven that's exactly what most small vessel owners do with a holding tank system .
Many times the best place for the tank near the head is under your bunk.
( sorry I had to)