Strange thing with waste system

[High Wire]

If you have a blocked vent path and then do a pump-out you can crush your holding tank like stomping on a beer can. It would be rare to have a tank built to withstand even a modest vacuum. The only savior is if the tank is almost full of liquid.

 

[Jgutten]

You cannot remove the vent from the outside. The only removal is from the inside. Mainship used a fuel vent for the head and it contains a charcoal filter. The first thing to do is to remove the filter. It causes more problems than it solves. Secondly, the vent line has too many twists and turns. Your vent line is plugged somewhere. It could be plugged at the tank from overfilling the tank. If you have the time, remove the vent line that was installed by Maniship and install a new 1" line. The vent enters the tank from the front side. I installed a new vent from the front towards the berth air conditioner, and installed a through hull next to the anchor drain through hole. Don't put a charcoal filter in. When installed, you can flush the vent line with a hose a few times per year. All this is laid out in Peggy Halls book, Getting Rid of Boat Odors. Works great.

Jeffrey F. Guttenberger
R Time
2005 Mainship 400

 

[HeadMistress]

Just to add to the confusion, I HAVE seen plugged vent lines (as opposed to the vent itself.) I suspect the PO over-filled the tank and forced waste into the vent line with every flush, after which it hardened in place. (Sorry for the graphic visual there!)

I did say "rarely, if ever"...it can happen. And not only if a tank is overfilled. Waste in a half-full tank on a sailboat can spill into the vent line--and into the toilet discharge line--when the boat heels if the vent and inlet fittings on the tank aren't in the right locations to prevent it, which they rarely are. But waste in vent lines only hardens if it's allowed to remain there while the boat sits. Back flushing the vent line every time the boat is washed and/or after every pumpout will prevent it.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[Shrew]

Just my .02. I've only had to deal with a handful of clogged vents over the years. In all my cases, it was either a corroded through-hull vent, or a corroded screen in the through-hull vent. Everything from slow filling fuel tanks that backflow fuel to slow filling water tanks, and hard to flush hand-pump heads.

I'll admit I have not seen the number of instances as Peggy or any other professional have seen, so my sample if very limited.

 

[woodlord]

I have a brass 90 degree fitting where the vent line attaches to waste tank It would plug there so I drilled and tap the top of the brass 90 and use a coat hanger to unclog then put threaded plug in where it was tapped
To help prevent it from getting plugged don’t Let tank fill up pump out
Just make sure you have released the pressure in tank before removing the plug
Hope it was useful

 

[HeadMistress]

Just my .02. I've only had to deal with a handful of clogged vents over the years. In all my cases, it was either a corroded through-hull vent, or a corroded screen in the through-hull vent. Everything from slow filling fuel tanks that backflow fuel to slow filling water tanks, and hard to flush hand-pump heads. I'll admit I have not seen the number of instances as Peggy or any other professional have seen, so my sample if very limited.

At least 95% of problems with any system on a boat--including the sanitation system--are preventable...due entirely to neglected preventive maintenance. The other 5% are caused by bad design, installation or both...or guests.

Woodlord said: I have a brass 90 degree fitting where the vent line attaches to waste tank

Brass has no place on a boat with the possible exception of a bell because it's highly susceptible to corroding (which is what prob'ly caused your vent fitting to clog). Metal fittings don't belong in a waste tank because metal and plastic or FB have different thermal co-efficients--meaning they expand and contract at different rates and in differing amounts which can cause 'em to leak or even result in a cracked female tank fitting in climates with temperature extremes. I'd replace the brass fitting with PVC or marelon...unless your tank is metal, in which case you'll be replacing it in a few years if not sooner. If it is, switch to a bronze or steel fitting.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[Seevee]

I've tried and tried to locate that vent line, unsuccessfully.... but will keep trying. I see where it comes into the boat, but it just ain't there on there other side. Any Mainships folk know? Thx.

 

[HeadMistress]

Iow, you've found the vent thru-hull on the outside of the boat, but there's no hose connected to it on the inside of it??? If so, you prob'ly haven't found the right thru-hull.

Try starting from vent fitting on the tank.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[Jgutten]

Sevee,

The holding tank vent on the Mainship 400 comes out of the front of the tank (bow end). It's accessible from the small floor hatch in the V berth. It goes forward on a 90 degree fitting, then goes to starboard, then turns toward the stern under the floor of the bathroom, then goes behind the air conditioner, turns to starboard again, goes up the gunwale to the vent. Makes sense, huh?

I've never seen a more ineffective and poorly designed system.

Remove it all and run a vent forward, straight, no major bends, slightly uphill, 1" line, next to the anchor locker drain.

Here's a picture of what my 90 degree fitting looked like. PLUGGED! The picture doesn't show that it's totally plugged at the bottom. Really really smelled foul!

Jeffrey Guttenberger
R Time
2005 Mainship 400

 

[Seevee]

After digging and looking, I can't see where the vent line comes into the boat. I can see where it should, but can't find it nor the inline filter. Any Mainship experts know how it's plumbed? The Mainship owners manual doesn't even show the vent.

However, it's been working fine the past few days.

 

[Seevee]

Sevee,

The holding tank vent on the Mainship 400 comes out of the front of the tank (bow end). It's accessible from the small floor hatch in the V berth. It goes forward on a 90 degree fitting, then goes to starboard, then turns toward the stern under the floor of the bathroom, then goes behind the air conditioner, turns to starboard again, goes up the gunwale to the vent. Makes sense, huh?

I've never seen a more ineffective and poorly designed system.

Remove it all and run a vent forward, straight, no major bends, slightly uphill, 1" line, next to the anchor locker drain.

Here's a picture of what my 90 degree fitting looked like. PLUGGED! The picture doesn't show that it's totally plugged at the bottom. Really really smelled foul!

Jeffrey Guttenberger
R Time
2005 Mainship 400
View attachment 75597

Jeffrey,

Ahhh, great and thanks. Good solution. Now how did you run a line forward? Did you run a snake backward or what do you have to removed to get access?

Mine looked pretty clean, will take it apart and blow thru it to see if it'a open. Where is the filter located? Might just remove that for now, as it would seem simple unless it's buried.

Thanks again, great info!

 

[HeadMistress]

The holding tank vent on the Mainship 400 comes out of the front of the tank (bow end). It's accessible from the small floor hatch in the V berth. It goes forward on a 90 degree fitting, then goes to starboard, then turns toward the stern under the floor of the bathroom, then goes behind the air conditioner, turns to starboard again, goes up the gunwale to the vent. Makes sense, huh? I've never seen a more ineffective and poorly designed system.

I have, including one vent line with a 360 degree loop in it. Boat builders have always been, and continue to be, the WORST sanitation plumbers on the planet! The only thing they did right in this one was put the vent fitting on the bow end of the tank.

Remove it all and run a vent forward, straight, no major bends, slightly uphill, 1" line, next to the anchor locker drain.

Yes! And use an open bulkhead thru-hull.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[HeadMistress]

Mine looked pretty clean, will take it apart and blow thru it to see if it'a open. Where is the filter located? Might just remove that for now, as it would seem simple unless it's buried.

Nooooo..it's always cheaper and easier to do anything right the first time than it is to do it over--which you'll have to do if you keep the existing vent. So do it right: Replace the vent line and run a new one that takes the shortest, straightest route possible to what I'm 90% certain will have to be a new thru-hull and get rid of any filter. Running it forward would be best (get some help to do it if you have to), but even out the side would be better than what you have now.

 

[jleonard]

I did say "rarely, if ever"...it can happen. And not only if a tank is overfilled. Waste in a half-full tank on a sailboat can spill into the vent line--and into the toilet discharge line--when the boat heels if the vent and inlet fittings on the tank aren't in the right locations to prevent it, which they rarely are. But waste in vent lines only hardens if it's allowed to remain there while the boat sits.

Yup, my boat was like that when I bought it, everything worked until the tank filled about 1/2 way. Fortunately the vent line was easy to access, ,and once I poked out the "paper mache" from the fitting the system has worked well ever since.

 

[Jgutten]

Sevee,

I've included pictures of the vent system that we installed on the Mainship 400.

Here's the new 1" vent line coming out of the front of the tank going forward.


Here's a picture of the new vent line going forward next to the forward air conditioning unit. We routed it on the starboard side of the AC unit.



Lastly, here's the new through hull vent in the bow. We can take a hose and flush it when needed.



You might want to hire someone to do this. It's a small space and you need t drill a hole through your hull in the bow.

Jeffrey F. Guttenberger
R Time
2005 Mainship 400

 

[Seevee]

Mine looked pretty clean, will take it apart and blow thru it to see if it'a open. Where is the filter located? Might just remove that for now, as it would seem simple unless it's buried.

Nooooo..it's always cheaper and easier to do anything right the first time than it is to do it over--which you'll have to do if you keep the existing vent. So do it right: Replace the vent line and run a new one that takes the shortest, straightest route possible to what I'm 90% certain will have to be a new thru-hull and get rid of any filter. Running it forward would be best (get some help to do it if you have to), but even out the side would be better than what you have now.

Peggy,

You're absolutely right, and will do. However, I'm using this daily right now (on the loop) and getting the supplies etc to add the forward vent will take time and looks like it could be a bit of a task, so now, I'll do the simple stuff that can be done easily.

I've got the tools, but need the parts.. hose, fitting, etc.

And I need to figure out how do get that line run.

 

[Seevee]

Sevee,

I've included pictures of the vent system that we installed on the Mainship 400.

Here's the new 1" vent line coming out of the front of the tank going forward.
View attachment 75615

Here's a picture of the new vent line going forward next to the forward air conditioning unit. We routed it on the starboard side of the AC unit.

View attachment 75616

Lastly, here's the new through hull vent in the bow. We can take a hose and flush it when needed.

View attachment 75617

You might want to hire someone to do this. It's a small space and you need t drill a hole through your hull in the bow.

Jeffrey F. Guttenberger
R Time
2005 Mainship 400

Jeffery,

Great into. getting it thru to past the AC a bit looks easy... need to figure out how to get it the rest of the way. How to you get to where the thru hull fitting will be attached? Where is the access to that small space?

 

[gaston]

Why have a air stink vent in the bow where you drive into the stink ??

 

[dhays]

Why have a air stink vent in the bow where you drive into the stink ??

With adequate ventilation and proper maintenance, there is no stink.

 

[HeadMistress]

With adequate ventilation and proper maintenance, there is no stink.

And and open vent thru-hull in the bow allows even a light breeze to force plenty of air into it any time the boat is underway or on an anchor or mooring...and also in the slip when the breeze is from the right direction.

If you'd read the chapter in my book (also available from Boatbooks Australia, btw) "Holding Tank Odor--Odor Out the Vent" you'd know why plenty of fresh air prevents holding tank odor.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[Comodave]

To determine where to drill a hole through the boat I tape a rare earth magnet on the inside where I think would be a good location. Then take another rare earth magnet outside and see where it sticks. If that location looks good, then I remove the magnets and drill the hole.

 

[Peter B]

Got one, thanks

My comment to Peggy was a poke in the ribs “tit for tat” since she dropped into a thread of mine last year about desiccating heads with some negative comments.

Ah, well, Murray. You will cop a bit of flak re your composter - I'll cop flak for my decision to replace a "proper boat toilet" with a simple camping type, but we have none of the issues covered in this thread.

So let them have at us. We both can easily convert back if a buyer so wished, but once you've enjoyed the sheer simplicity of either of our systems, why would anyone want to..?

Ok, if a newer boat, well designed from the outset to have plumbed toilets, holding tanks, pump-out and vent lines - and even level indicators - well fine..! I'd use then too. But about 10 years down the track...all sorts of stuff has built up, and s**t starts to happen even to those lovely installations. Peggie has made a living out of helping solve exactly that stuff, after all. Our case rests..?

 

[gaston]

Ah, well, Murray. You will cop a bit of flak re your composter - I'll cop flak for my decision to replace a "proper boat toilet" with a simple camping type, but we have none of the issues covered in this thread.

So let them have at us. We both can easily convert back if a buyer so wished, but once you've enjoyed the sheer simplicity of either of our systems, why would anyone want to..?

Ok, if a newer boat, well designed from the outset to have plumbed toilets, holding tanks, pump-out and vent lines - and even level indicators - well fine..! I'd use then too. But about 10 years down the track...all sorts of stuff has built up, and s**t starts to happen even to those lovely installations. Peggie has made a living out of helping solve exactly that stuff, after all. Our case rests..?

Was thinking about your dunny Peter I sopose its quite easy to empty it over the side at midnight

 

[Peter B]

Was thinking about your dunny Peter I sopose its quite easy to empty it over the side at midnight

Yup. Not even midnight. It's ok to dump it in our waters well clear of shore, marinas, commercial fishing beds, etc. Or in domestic sewage systems. It is chemically treated. Probably not in US waters, as they are more 'anal' over there - or is it because they just have more an....are better not...

 

[Bacchus]

If you have a blocked vent path and then do a pump-out you can crush your holding tank like stomping on a beer can. It would be rare to have a tank built to withstand even a modest vacuum. The only savior is if the tank is almost full of liquid.

Maybe a dumb question but won't the tank / pump out vent / pull air in through the head bowl to prevent a collapse?

 

[gaston]

Maybe a dumb question but won't the tank / pump out vent / pull air in through the head bowl to prevent a collapse?

yes!

 

[HeadMistress]

Maybe a dumb question but won't the tank / pump out vent / pull air in through the head bowl to prevent a collapse?

One of the first clues that the vent is blocked is a hissing in the toilet during pumpout. It may or may not allow enough air into the tank to prevent the pumpout from imploding the tank...that depends on how strong the pumpout is. Rely on that as a substitute for preventive maintenance at your own risk.

I honestly believe that if most boat owners paid as little attention to their engine maintenance as you do to every other system, every TowBoat franchisee would be be a millionaire

Peggie
Prevention is always cheaper and easier than cure.

 

[timb]

are there any fittings that can be installed into an existing fiberglass tank easily ? mine has a little chrome 90 that looks like it's 1/2" or so . I also saw that even though there suppose to have all fittings in the top I have none in the top.

 

[Comodave]

are there any fittings that can be installed into an existing fiberglass tank easily ? mine has a little chrome 90 that looks like it's 1/2" or so . I also saw that even though there suppose to have all fittings in the top I have none in the top.

Peggie knows about one. She turned me onto one several years ago. I don’t remember the name of the company anymore.

 

[woodlord]

The sending unit for the tank level indicator can be ordered with or without vent in it I would get one with vent and clamp the vent hose on it