Dennis Gibbons wrote:
Peggy,
Have you ever heard of the following setup:

The waste tank is ABOVE the water line with a bottom drain to a seacock.
There is a second drain from the top of the tank to the deck pumpout.
The head pumps up to the top of the tank.
Close the seacock in protected water to keep the bad stuff aboard and then
open the seacock when you get out.When offshore, simply leave the seacock
open to drain as you go (so to speak).

I'm not crazy about that set up. When the seacock is closed waste has to
sit in the line to thru-hull, permeating the hose...any sludge in the
tank will end up in that hose, so if you're in coastal waters very long,
that can cause problems...and I can't see any reason to go through a
tank at sea instead of flushing directly overboard. If the tank vent
should become blocked, you'll have problems flushing the toilet due to
the backpressure. Worst case would be a blocked tank vent AND a clogged
overboard discharge hose at sea in 8'+.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html

Dennis Gibbons wrote:
Peggy,
Have you ever heard of the following setup:
The waste tank is ABOVE the water line with a bottom drain to a
seacock.
There is a second drain from the top of the tank to the deck pumpout.
The head pumps up to the top of the tank.
Close the seacock in protected water to keep the bad stuff aboard and then
open the seacock when you get out.When offshore, simply leave the seacock
open to drain as you go (so to speak).

That is _nearly_ exactly the set-up that I have, with one important
modification, see after Peggie's comment.

Peggie Hall writes:


I'm not crazy about that set up. When the seacock is closed waste has
to sit in the line to thru-hull, permeating the hose...any sludge in
the tank will end up in that hose, so if you're in coastal waters very
long, that can cause problems

Right. So what I did is to have a PVC ball valve right at the drain,
then go with sanitation hose (the good one, of course) to the
seacock. Both the PVC ball valve and the seacock are usually closed
and only open off-shore for draining the tank. Thus, the hose ONLY
ever contains sea water (or antifreeze, in winter), except for brief
periods during draining. And after draining the tank I would pump
enough sea water through it (using the existing pump, i.e. through the
head) to make sure it is clean before closing both valves again. Just
like you pump fresh water into the tank when pumping it out.

Of course, I have never done it so far since I was always within 3
miles.

...and I can't see any reason to go
through a tank at sea instead of flushing directly overboard.

Oh, reason is options, and simplicity. I can sail legally in coastal
waters and without problems off-shore. True, having some construction
with Y-valves, or additional pumps and dip tubes would also work (and
actually have some advantages), but this setup is far simpler.

If the
tank vent should become blocked, you'll have problems flushing the
toilet due to the backpressure. Worst case would be a blocked tank
vent AND a clogged overboard discharge hose at sea in 8'+.

--
Peggie

OK, this part I don't understand. Why would a second drain block the
vent(s)??

--Ernst

Dennis Gibbons wrote:
Peggy,
Have you ever heard of the following setup:
The waste tank is ABOVE the water line with a bottom drain to a
seacock.
There is a second drain from the top of the tank to the deck pumpout.
The head pumps up to the top of the tank.
Close the seacock in protected water to keep the bad stuff aboard and then
open the seacock when you get out.When offshore, simply leave the seacock
open to drain as you go (so to speak).

That is _nearly_ exactly the set-up that I have, with one important
modification, see after Peggie's comment.

Peggie Hall writes:


I'm not crazy about that set up. When the seacock is closed waste has
to sit in the line to thru-hull, permeating the hose...any sludge in
the tank will end up in that hose, so if you're in coastal waters very
long, that can cause problems

Right. So what I did is to have a PVC ball valve right at the drain,
then go with sanitation hose (the good one, of course) to the
seacock. Both the PVC ball valve and the seacock are usually closed
and only open off-shore for draining the tank. Thus, the hose ONLY
ever contains sea water (or antifreeze, in winter), except for brief
periods during draining. And after draining the tank I would pump
enough sea water through it (using the existing pump, i.e. through the
head) to make sure it is clean before closing both valves again. Just
like you pump fresh water into the tank when pumping it out.

Of course, I have never done it so far since I was always within 3
miles.

...and I can't see any reason to go
through a tank at sea instead of flushing directly overboard.

Oh, reason is options, and simplicity. I can sail legally in coastal
waters and without problems off-shore. True, having some construction
with Y-valves, or additional pumps and dip tubes would also work (and
actually have some advantages), but this setup is far simpler.

If the
tank vent should become blocked, you'll have problems flushing the
toilet due to the backpressure. Worst case would be a blocked tank
vent AND a clogged overboard discharge hose at sea in 8'+.

--
Peggie

OK, this part I don't understand. Why would a second drain block the
vent(s)??

--Ernst

brain wrote:

...and I can't see any reason to go
through a tank at sea instead of flushing directly overboard.

Oh, reason is options, and simplicity.

"Options?" What options? It offers none...all the waste has to go
through the tank, no way to bypass it. It also means that waste has to
go uphill to the tank, leaving the head discharge hose full of standing
waste. So you have two hoses begging to become permeated. And in your
case, a ball valve that prob'ly won't work because you don't sail
outside 3 miles often enough to keep it from seizing.

A pump in one of the tank discharge lines, a y-valve in the head
discharge line...not much more complicated, and now you have options.

OK, this part I don't understand. Why would a second drain block the
vent(s)??

It wouldn't...one has nothing whatever to do with the other. But Murphy
was an optimist who prob'ly based his law on the typical boat owner's
approach to marine sanitation system maintenance. Tank vents,
especially on sailboats due to waste running out them when heeled, are
highly prone to clogging if owners don't backflush 'em regularly--which
few do (and when the tank pressurizes, it's last thing owners think
of...they think it's due to a clog in the discharge line, often with
disastrous results). Nor do many owners ever flush out their tanks to
eliminate sludge buildup. Worst case would be a blockage in both lines
occurring simultaneously...no escape for displaced air in either
direction--out the vent or down the discharge.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html

brain wrote:

...and I can't see any reason to go
through a tank at sea instead of flushing directly overboard.

Oh, reason is options, and simplicity.

"Options?" What options? It offers none...all the waste has to go
through the tank, no way to bypass it. It also means that waste has to
go uphill to the tank, leaving the head discharge hose full of standing
waste. So you have two hoses begging to become permeated. And in your
case, a ball valve that prob'ly won't work because you don't sail
outside 3 miles often enough to keep it from seizing.

A pump in one of the tank discharge lines, a y-valve in the head
discharge line...not much more complicated, and now you have options.

OK, this part I don't understand. Why would a second drain block the
vent(s)??

It wouldn't...one has nothing whatever to do with the other. But Murphy
was an optimist who prob'ly based his law on the typical boat owner's
approach to marine sanitation system maintenance. Tank vents,
especially on sailboats due to waste running out them when heeled, are
highly prone to clogging if owners don't backflush 'em regularly--which
few do (and when the tank pressurizes, it's last thing owners think
of...they think it's due to a clog in the discharge line, often with
disastrous results). Nor do many owners ever flush out their tanks to
eliminate sludge buildup. Worst case would be a blockage in both lines
occurring simultaneously...no escape for displaced air in either
direction--out the vent or down the discharge.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html

Peggy -- I think SunMar makes one that doesn't need any power, but they do
require that "excess fluid drainage" that you mention. Some of those that
require power claim to be able to dry the "fluid" sufficiently not to
actually use the overflow under lower usage (one or two people full-time),
but they're also way too big for my boat.

--
Karin Conover-Lewis
Fair and Balanced since 1959
klc dot lewis at centurytel dot net


"Peggie Hall" wrote in message
...
Karin Conover-Lewis wrote:
Ditto the "Lavac" recommendation. I would have no other. Well, I'd go
for a
composting head if I didn't need to carry mountains of peat moss and it
fit
the same space as the Lavac, but such a creature doesn't exist.

Composting toilets also need power 24/7, Karin, to run the blower and
evaporator. Also a means of draining off liquids that exceed what can be
evaporated, which in coastal waters means some kind of container for
'em...'cuz they can't legally be drained overboard. Composter are an
alternative worth considering on a large powerboat on inland "no
discharge" waters, but IMO are totally impractical on any boat in
coastal waters.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html
http://shop.sailboatowners.com/detai...=400&group=327

Peggy -- I think SunMar makes one that doesn't need any power, but they do
require that "excess fluid drainage" that you mention. Some of those that
require power claim to be able to dry the "fluid" sufficiently not to
actually use the overflow under lower usage (one or two people full-time),
but they're also way too big for my boat.

--
Karin Conover-Lewis
Fair and Balanced since 1959
klc dot lewis at centurytel dot net


"Peggie Hall" wrote in message
...
Karin Conover-Lewis wrote:
Ditto the "Lavac" recommendation. I would have no other. Well, I'd go
for a
composting head if I didn't need to carry mountains of peat moss and it
fit
the same space as the Lavac, but such a creature doesn't exist.

Composting toilets also need power 24/7, Karin, to run the blower and
evaporator. Also a means of draining off liquids that exceed what can be
evaporated, which in coastal waters means some kind of container for
'em...'cuz they can't legally be drained overboard. Composter are an
alternative worth considering on a large powerboat on inland "no
discharge" waters, but IMO are totally impractical on any boat in
coastal waters.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html
http://shop.sailboatowners.com/detai...=400&group=327

Peggie,
Question have you ever heard of or used forded mechanical aeration of marine
holding tanks?
Two options come to mind 1.) install a 10 VDC computer chip cooling fan in a
tank vent line where the tank has two vents. for example a 5.3 CFM (free
air) fan draws 1.08 watts power (at 24/7 operation this is about 2.2 AH
draw) and is about 1-1/2" diameter which can be adapted to fit in-line in
one of the vent hoses. 2.) better solution a battery powered AQUARIUM AIR
PUMP available on the shelf at PETCO for $13.00. It comes with its own air
release stone that would be dropped into the holding tank and feed through a
3/8? O.D. plastic hose that is run-through the wall of one vent line. the
air pump is quite and aerates the stored liquid much as a commercial
wastewater sewage treatment facility not just the surface layer like tank
vents. The air pump is designed to hold two C-size batteries with an
estimated 2-week life or about 1.3 AH on a 24/7 operation schedule. KISS
would be to replace the "Dry-Cells" every two weeks, but if someone wanted
to get really fancy with this installation they could install rechargeable
C-Cells and hook them into either a solar panel (al-a NICRO-VENT or into the
12 VDC "House" battery through a dropping resister to get the 3 VDC at the
air pump.
I realize that these options add another level of complication to the marine
head equation but it does away with all odor problems without the cost of
additional of chemicals.
What is your opinion on either of these mechanical aeration schemes.
Jim Maxey ME

"Peggie Hall" wrote in message
...
Peggie, I have a question, kinda related to this thread. I think I've
read/understood that a well "aired" holding tank is the best way
to reduce oders.

Yep...oxygen is the key to odor elimination.

So, being an engineer, I'm wondering if a two
hose holding tank vent arrangement...one "inlet" and one "outlet",
might work.
The forward hose leads to the bow, the aft hose leads to the
stern.

It would actually work better if both lines went forward...'cuz that
would mean air would be forced into the tank no matter which tack you're
on. Nor does it require two vent lines if the vent line is short enough
( 5') and has a 1" ID...'cuz air forced in has no trouble pushing
gasses in the tank out the same line.

The theory is that there would be constant airflow into,
(and out of) the holding tank. assuming the vents at each end
encouraged such flow.

A line leading aft that's too long wouldn't be under enoug pressure to
get the job done without an inline exhaust fan to help it. You'd
actually be better off with a single 1" short vent.


Is this a stupid idea?

Noooo...not stupid at all! It only proves you're thinking in the right
direction. I'd have to see a diagragm of your installation before I
could tell you what you need to do to make it work.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html

On Sun, 9 May 2004 16:54:04 -0700, something compelled "jmax"
, to say:

What is your opinion on either of these mechanical aeration schemes.

Simpler is better, at least for me. I have ordered a seat that
will sit on top of a five gallon bucket. You line it with a
plastic garbage bag. Use it, tie the bag shut, and store it
until you find a trash can.

No leaks, no clogs, no thru hulls, no funky odor. Yes, it's a
little gross, but not more so than when the whole system packs it
in and you're reduced to hanging it over the rail.

jmax wrote:
Peggie,
Question have you ever heard of or used forced mechanical aeration of marine
holding tanks?

Yep...in fact, Groco makes a holding tank aeration system...they call it
the Sweetank System. See it at http://www.groco.net

Two options come to mind...

You seem to be describing two different systems...a fan in a vent line
doesn't aerate, it only ventilates the airspace above the surface. And
in tanks smaller than about 30 gallons, that aren't more than about 18",
ventilation along with with an organic (bio-active or nitrate) tank
treatment should be enough to create the aerobic environment needed to
prevent odor. It does require two vents, and the fan should be be an
exhaust fan that pulls air through, not one that pushes air into the tank.

An aerator oxygenates the contents, and properly designed and installed
for the size of the tank, completely eliminates odor without the use of
any tank products. But the key is a pump big enough for the tank size,
and a system inside the tank that distributes the air throughout the
whole tank...a too-small pump and/or just a single column of air would
only push noxious gasses out the vent. It's also important to remember
that while fish tanks only contain water, waste is full of animals fats
that routinely clog up gauge senders...and can clog up the aerator too
if the design doesn't prevent it.

By the time you go through all that's needed to design and retrofit a
DIY aerator that won't create more problems than it solves, it might be
cheaper just to buy one. The Groco Sweetank has a list price of around
$250...WM quite often has it on sale for around $150. Even that sounds
like a lot till you compare it to the total amount spent on holding tank
products over a couple of years.

Both aerators and vent fans have to run 24/7/365 (except during winter
layup of course) to keep the tank aerobic. A tank that's turned septic
can be recovered, but it takes several hours, and the odor forced out
the vent is horrific for at least the first hour...then gradually
diminishes over the next 3-6 hours depending on the size of the tank.
That COULD make your battery powered pump a bit problematic if the
batteries aren't changed regularly...and batteries run up the cost too.

IMO, a far better solution than any of the above is a Type I MSD (CG
certified device that treats waste and discharges overboard legally in
all waters except those specifically designated "no discharge," which
are few and far between in coastal waters. Why have to deal with the
problems of storing waste aboard if you don't have to?

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://69.20.93.241/store/customer/p...40&cat=&page=1