How does the macerator work?

Sailgunner · Feb 19, 2013

What do you mean nothing comes out? My macerator pumps the waste from the holding tank to the sea. Obviously the thru hull valve needs to be open.

Don Lucas · Feb 19, 2013

You have had your boat at least 3 years and you don't know whether you have a hull valve for the holding tank discharge????

I'm just plain scared for you!

Does this mean that you have never had to use your marerator for 3 years?

Bill Roosa · Feb 19, 2013

Just mentioning that he turned it on will get him in trouble unless he can demonstrate he was NOT in the Chesapeake Bay.
While it is ok to dump 2,000,000 persons' worth of poo into the bay your 2 person boat poses a severe environmental threat that has been highly regulated.

Bob 04 H260 · Feb 19, 2013

We also have the macerator pump on our holding tank and a thru-hull valve. I don't see anyway to lock this thru-hull valve closed ? is that not required when a pump is used between the tank and thru-hull ?

thanks Bob

Bill Roosa · Feb 19, 2013

yes a lock is required to be fitted when in inland waters. And the USCG will check if you start copping an attitude with them. They are much more concerned with safety than checking your plumbing so if they see you made the attempt while checking something nearby they probably will not say a thing.
A zip tie will suffice if it keeps the valve from being moved from closed. It does not have to secure the valve against godzilla

Sailgunner · Feb 20, 2013

I could never see how to tie the valve closed. Tying it open would be easy. We were boarded by the coasties last summer on the ICW and they said the valves should be tied closed but didn't make a big deal about it and gave us a clean inspection.

faisond · Feb 20, 2013

The Jabsco macerators have a rubber impeller which combined with a metal blade reduce the size of the incoming flow and pump it out The rubber impeller can wear out and spin on the shaft. The motor will whir away nicely but the macerator will not work. Jabsco sells a rebuild kit. It's an easy 30-minute job. Not the most pleasant but easy.

Chef2sail · Feb 22, 2013

Mike H. said:
The diagrams I find show a 3 way valve between the macerator and the tank. Is there, or should there be one?

Also, shouldn't the suction for the tank be connected to a pipe that extends into the tank almost to the bottom? I don't remember seeing one in my poly tank.

Ok lets start at page 1

Trace the discharge hose from the bottom of the toliet to the holding tank. From the holding tanlk there should be two other hoses. A small diameter 1/2" or so one which goe to the vent on you hull somewhere which allows air into the holding tank to promote aerobic organisms to prevent smell. The second hose ( shoud be 11/2 inches) is the discharge hose from the tank. Follow it. Since you say the diagram says there is a 3 way valve it leads to that. Ours is a marlon one with a hole in it for a lock to lock the macerater side per the CG regulatons. This three way valve should have two 1/1/2 inch hoses off of it, one leads to the deck pump out which you do at the dock. The second hose should lead to a masecrator pump....then from the back end of the pump a hose should lead to a thru hull with a stop cock. In order to pump waste out ( you have to be outside the 3 mile limit and never in the Chessie), you turn the three way valve so it is leading to the macerator and then you open the stop cock valve to the thru hull. If it is working youll know, you will hear grinding:neutral: and there will be bubbling and sh--t beside your boat.

Bob 04 H260 · Feb 22, 2013

Our plumbing diagram does not show a 3 way valve.

The head goes direct to the holding tank.
The pumpout goes direct to the holding tank.
The macerator hose comes direct out of the bottom of the holding tank to the pump to a regular thru-hull.

As a previous poster said easy to lock one of these open with the handle vertical but not as easy to lock it in the closed position......I was thinking about two wire ties, one around the base of the thru-hull, the other going from the hole in the handle down to the first wire tie, when the valve is in the off position. If an actual lock is not required then this should be legal ?

The boat is 10 years old and no one has done anything about it yet so I don't know if I am trying to solve a problem that does not exist ?

Bob

robertsapp · Feb 26, 2013

It's common for the macerator impeller and blades to decay away, but the motor will be fine. So you turn it on and you can hear it whirring, but nothing pumps. Personally I find it easier to just replace the entire thing rather than try to rebuild one. I haven't had much luck getting the darn things apart once they're a few years old, while it's usually not that hard to just remove and replace it.

Hunter seemed to favor a design where the toilet pumps directly to the holding tank, with no wye valve and option for overboard discharge as most boats have. The tank then has an overboard pumpout line, into which the macerator line connects through a "T" and discharges through a thru-hull valve. It's never been clear to me whether it is legally necessary to lock this valve. The rule was really written for the wye valve you would expect to find between the head and the tank, which would allow you to discharge directly overboard if it was incorrectly positioned. In the design Hunter used, you could have your thru-hull open, and you still couldn't discharge sewage unless you turned on the macerator pump. I could argue that you should have one of those locking covers over the macerator breaker and it would be more effective than a lock on the thru-hull. No idea what the Coast Guard might think though.

Oh, and the small vent line is just there to equalize the pressure in the tank so you don't pressurize it when you pump the head, which will force poop and odor back into the bowl. It also prevents the tank from collapsing when you do a pumpout. It really doesn't function to provide airflow to support aerobic digestion unless it's at least an inch in diameter and has a short run with no more than a 45 degree agle from horizontal. The small, usually vertically routed vents Hunter installed don't pass enough air naturally to promote aerobic digestion in the tank.

Chef2sail · Feb 27, 2013

robertsapp said:
Hunter seemed to favor a design where the toilet pumps directly to the holding tank, with no wye valve and option for overboard discharge as most boats have. The tank then has an overboard pumpout line, into which the macerator line connects through a "T" and discharges through a thru-hull valve. It's never been clear to me whether it is legally necessary to lock this valve. The rule was really written for the wye valve you would expect to find between the head and the tank, which would allow you to discharge directly overboard if it was incorrectly positioned. In the design Hunter used, you could have your thru-hull open, and you still couldn't discharge sewage unless you turned on the macerator pump. I could argue that you should have one of those locking covers over the macerator breaker and it would be more effective than a lock on the thru-hull. No idea what the Coast Guard might think though.

Oh, and the small vent line is just there to equalize the pressure in the tank so you don't pressurize it when you pump the head, which will force poop and odor back into the bowl. It also prevents the tank from collapsing when you do a pumpout. It really doesn't function to provide airflow to support aerobic digestion unless it's at least an inch in diameter and has a short run with no more than a 45 degree agle from horizontal. The small, usually vertically routed vents Hunter installed don't pass enough air naturally to promote aerobic digestion in the tank.

Hunter used a different design than my C&C and many other boats by your post explaination.

Many other boat manufacturers and after market installs the head directly pumps into the holding tank. The "Y" valve to decide direction of waste flow. whether you are going to the deck pump out or the mascerator pump then thru hull comes after the holding tank.

http://www.westmarine.com/webapp/wc...gId=-1&storeId=11151&page=Heads-Holding-Tanks

The advantage of this setup is that the authorites seem to not hassel the "y" valve being downsteam of the tank vs the toliet.

As far as the vent line, I dont think you are completely correct. While yes it does help the pressure to remain equalized in the tank, the best diameter is at least 3/4" hose. Better as you said if 1" or even 1.5" This should be installed with as few turns/ bends as possible and try to keep less than 5 feet from the vent on the hull.

The real advantage of this hose is to allow air flow into you tank to promote the growth of aerobic bacteria and thus keep the smell down in your system. If Hunter didnt design/ install these vents correctly or the hose diameter isnt large enough to allow the air in correctly I would suggest replacing them.

My information is backed by the well respected "expert in sanitation" Peggy Hall in her responses in the embedded link. Her book on sanitation systems is the leading reasource for many boat owners. She is great at responding also. I have followed her advice on all things sewearge.

http://www.cruisersforum.com/forums/f115/holding-tank-vent-line-75696.html

On Haleakula we actually have two 3/4 inch vent lines...I installed a second one...and we also only use fresh water in our holding tank. We eleiminated our "smelly" problem years ago. ( of course the correct hoses are so important- i like the green stripe Trident)

Dave

robertsapp · Feb 27, 2013

If you look at the labled diagram on the West Marine site, that's exactly what Hunter installed on our boat and many many others, except there's no #8 wye valve. They just used a PVC "T" fitting. That's why I've never been clear on whether it's a requirement to lock the thru-hull. Even if it's open, the only way it's going to pump sewage is if you energize the macerator pump. Plus on our boat you have to climb out onto the swim platform and open a locker to reach this valve. So if the Coast Guard ever were to stop me, I know I'll be tempted to say "Seriously? I have to crawl off the back of the boat, hang upside down in a locker, open a valve, then climb back onboard, enter the cabin, and energize a breaker. Don't you think that's a better deterent to inadvertant discharge than just unlocking a lock?" But then that's me channeling my inner pirate.

robertsapp · Feb 27, 2013

Chef2sail said:
My information is backed by the well respected "expert in sanitation" Peggy Hall in her responses in the embedded link. Her book on sanitation systems is the leading reasource for many boat owners. She is great at responding also. I have followed her advice on all things sewearge.

Dave

Peggy will tell you that if the vent line follows a path that's steeper than 45 degrees, it just won't pass enough air to keep the tank oxygen rich enough. Hunter only used a 5/8" line, it has about a two or three foot vertical rise in it on our boat, and they even put a loop at the hull vent to prevent backwash from waves hitting the vent. Works great for pressure equalization, but does bupkiss for promoting aerobic digestion in the tank.

Chef2sail · Feb 27, 2013

There are a bunch of diagrams. I guess you are referring to one that has optional discharge. The one similar to mine and many others other than Hunters which I have seen and worked on are like the last two diagrams. Now with multiple discharge and one with possible below the waterline applications, which could be any boat which heels. Both have preventative anti siphon loops. Both have the "Y" located post holding tank.

Chef2sail · Feb 27, 2013

I guess your holding tank is greater than the 5 feet Peggy suggests. The 45 degree angle to a vent above the waterline should not present difficulty unless of course you holding tank is located on the bilge. Most boats I have seen have no problem with this as the holding tanks are located under the v berths, setees, or compartments close to the head. Most I have seen have the tops of the tanks located above the water line, so the outlet of the vent hose from the tank iis also above the waterline.

Ever since I straightened out the vent lines on Haleakula and added the additional 3/4" vent line the smells vanished. We never had a pressure problem in the tank despite its previous set up with a 90 degree angle and we were luck it never clogged there . Her suggestions about venting lead to increased aerobic growth and solved our problems. Have you written to Hunter Marine discussing with the what appears to be a design issue since you are saying its present in all their vessels. That may help them in looking at improving for future boats.

I have followed Peggy's advice to a "T" on our boat waste management and it has improved our vessels system. The proof is in the pudding as they say.

Dave