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Old 19-01-2021, 00:11   #1
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Macerator necessary?

Lavac vacume head, to holding tank, then to outlet. Replaced whale manual with a TMC 12v pump. Is a macerator essential please?
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Old 19-01-2021, 02:52   #2
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Re: Macerator necessary?

I would guess that it is not a 'essential' but it is 'highly beneficial'.
All the pump does it to suck the waste from the bowl and push it through tho hose to the holding tank. Manual toilets usually do not have macerators.
On the other hand, electric toilets usually do as it shreds the waste to more easily transferred state and ensures easier flow.
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Old 19-01-2021, 03:07   #3
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Re: Macerator necessary?

what the man said...

macerators mince everything up quite fine so the slurry pumps / moves easily (and without those nasty blockages !)

not essential but 'highly recommended'

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Old 19-01-2021, 03:36   #4
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Re: Macerator necessary?

In Oz, discharged sewerage is required to by macerated so that may apply across the ditch too?
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Old 19-01-2021, 04:11   #5
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Re: Macerator necessary?

Quote:
Originally Posted by meirriba View Post
All the pump does it to suck the waste from the bowl and push it through tho hose to the holding tank.
The manual Henderson Mk V diaphragm pump does produce quite a fine result, that to my eyes looks indistinguishable from that of a working electric macerator.

In fact, I've sailed through trails from charter dive boats, theoretically equipped with macerators, that definitely contained stool that I would judge unmacerated.

At least in Queensland, Australia, any LEO inspecting wants to see an electric macerator.

Having a Lavac with a Henderson pump does not satisfy them - they are not interested in looking at the product of the Lavac-Henderson combination, only seeing the equipment.
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Old 19-01-2021, 07:53   #6
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Re: Macerator necessary?

Solid waste is 75% water, is broken up pretty well by any marine toilet pump, and so dissolves fairly quickly in water without any maceration.

Marine/RV TP also dissolves quickly in water without maceration, but it's not necessary to pay the high price for TP labeled "marine/rv" to have the same thing. Any TP that can pass this test will dissolve just as quickly: put a sheet or two in a mason jar or glass of water...wait an hour or two, then shake or stir the jar or glass. If the water is "milky" and all you see is "snow," it's safe to flush in any marine toilet. But if the sheet(s) are still intact or mostly intact, try another brand.

Australia is the only country I know of that requires maceration. That may be because they allow the discharge of raw sewage from a tank or directly from the toilet to go directly overboard only a mile from shore, whereas the "3 mile limit" or even further offshore is the norm in most countries.

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Old 20-01-2021, 11:13   #7
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Re: Macerator necessary?

After a big burst of activity about 10-15 years ago after they bought in new regulation to comply with MARPOL or something they appear to have settled down on the policing of marine toilet facilities in Queensland and there are no pump out facilities anyway. NSW is still a bit anal retent but they do appear to have plenty of pump out facilities. I did notice that one marina wanted $30 a pump out which I thought a little steep.

If you are pumping out a holding tank with an electric pump it would not do any harm to use one with a macerator anyway.
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Old 20-01-2021, 11:19   #8
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Re: Macerator necessary?

Quote:
Originally Posted by vic008 View Post
Lavac vacume head, to holding tank, then to outlet. Replaced whale manual with a TMC 12v pump. Is a macerator essential please?
No t is NOT essential. It is another lump of complexity awaiting failure at an inopportune moment.

In fact I have only one pump, a standard Lavac/Henderson, and I valve it so it:
Empties toilet overboard
Empties toilet to holding tank
Empties holding tank overboard

Both boats rigged the same way.

As was said above, I can see no effectual difference between its output and that of a mascerator, and ai have had both.
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Old 20-01-2021, 11:31   #9
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Re: Macerator necessary?

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Originally Posted by vic008 View Post
Lavac vacume head, to holding tank, then to outlet. Replaced whale manual with a TMC 12v pump. Is a macerator essential please?
It really depends on which part of the system you're referring too.

A manual head typically uses 1 1/2" sanitation line from the head to the holding tank.

A vacuflush head typically uses 1 1/2" sanitation line from the head to the accumulator tank

Frequently the vacuflush will use a macerator to a 1" line from the accumulator tank to the holding tank.

On electric heads, there is a macerator at the head and the sanitation line from the head to the holding tank is 1".

For overboard discharges, it is usually a 1 1/2" line from the holding tank to a macerator, then a 1" line from the macerator to the throughhull.

If you're going from accumulator tank to holding tank, I would think you'd use a macerator. If not, I wouldn't use 1" line between the accumulator tank and the holding tank. IMHO a 1" line from accumulator tank to holding tank with no macerator would a recipe for problems.

If you're going from holding tank to through hull for discharge, again, I would think you would use a macerator. If not, I would certainly not use 1" line, but again, I think the lack of macerator is a recipe leading to potential servicing.

In short, once elbow deep in sanitation repairs, ask yourself if saving a few hundred dollars on a macerator is worth it.
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Old 20-01-2021, 12:43   #10
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Re: Macerator necessary?

Macerator pumps are the second most-prone-to-failure component on my boat, bilge pump float switches being most prone. I believe I have renewed the macerator on my boat every season for the last ten years. I’m at the point when my family asks “What do you want for your birthday”, I say “A new macerator pump would be nice”.

I gave up on bilge pump float switches years ago, unfortunately I can’t give up on macerator, my boat has no pump-out system and in any case finding a pump-out facility that works is harder than finding a macerator pump that does.

I’m actually going to my boat this morning to again figure out how/where to empty the contents of the holding tank to a point where I can successfully remove the pump for replacement.

They are absolute junk and if I could get by without one I would. Up until now I haven’t found a suitable substitute. If you find one, please post it here.
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Old 20-01-2021, 13:11   #11
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Re: Macerator necessary?

Quote:
Originally Posted by Shrew View Post
It really depends on which part of the system you're referring too.

A manual head typically uses 1 1/2" sanitation line from the head to the holding tank.

A vacuflush head typically uses 1 1/2" sanitation line from the head to the accumulator tank

Frequently the vacuflush will use a macerator to a 1" line from the accumulator tank to the holding tank.

On electric heads, there is a macerator at the head and the sanitation line from the head to the holding tank is 1".

For overboard discharges, it is usually a 1 1/2" line from the holding tank to a macerator, then a 1" line from the macerator to the throughhull.

If you're going from accumulator tank to holding tank, I would think you'd use a macerator. If not, I wouldn't use 1" line between the accumulator tank and the holding tank. IMHO a 1" line from accumulator tank to holding tank with no macerator would a recipe for problems.

If you're going from holding tank to through hull for discharge, again, I would think you would use a macerator. If not, I would certainly not use 1" line, but again, I think the lack of macerator is a recipe leading to potential servicing.

In short, once elbow deep in sanitation repairs, ask yourself if saving a few hundred dollars on a macerator is worth it.
ALL connections are 1-1/2”.

Ince deep into sanitation repairs ask if the additional complexity worth it.

I am talking Lavac heads and Hederson pump.
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Old 20-01-2021, 13:44   #12
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Re: Macerator necessary?

Fwiw, failure to rinse out a macerator after each use is the most common cause of failure. 'Cuz waste is is sticky, so when allowed to remain in the pump, it causes impellers to get stuck to the inside of the housing...then startup either breaks off one or more impeller vane or causes the motor to overheat enough to shut it down. Although sea water is sticky too, it's not as sticky as waste, so it's better than nothing to us to rinse behind each tank dump.

If you can't do that, the Dometic (formerly SeaLand) T-Series pump is an electric diaphragm pump that can run dry without harm for a LONG time and is just about indestructible...I had one on one of my own boats that was 11 years old and still going strong when I sold the boat. Although the diaphragm isn't as likely to get firmly stuck to its housing if you're not meticulous about rinsing it out, it's a good idea to give it bath every now and then.

It doesn't macerate, but maceration really isn't necessary 'cuz solids and quick-dissolve TP dissolve in the tank very quickly. And I strongly suspect that it would be a rare Aussie potty patrol person who'd know that an electric overboard discharge pump isn't a macerator pump.

It's a bit pricy, but not nearly as pricy as a new macerator pump every year. I don't know who carries it in OZ...this link to the US retailer will at least let you see what it looks like, specs etc and may give you an idea of what your cost would be based on rate of conversion. Dometic T-Series pump @ Defender


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Old 20-01-2021, 15:56   #13
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Re: Macerator necessary?

Thanks for the response Peggy. Just maybe some advice on design which may be contributing to premature failure:

I designed my tank to have the pump mounted at the top with a rigid suction line running from the pump mount down to the bottom of the tank. The purpose of this is so that when the pump packs up (note: not if ) I can remove it without having whatever is in the tank running out.

The possible weakness with this is that the pump has to draw material up the pipe which takes about 1.5 seconds, a period during which the impeller runs dry. Yes I know that running dry is “not permitted” but 1.5 seconds is not enough time for the pump impeller to get hot.

Normal practise is to run the pump until the tank is empty evidenced by a change in the tone of the pump. Then we pump 20 litres of seawater into the tank via the toilet which is then also pumped out (to rinse the system).

In your experience is a 1.5 second dry run enough to cause impeller failure? I ask this only anecdotally because it is actually quite rare for the pump to fail because the impeller. It’s normally seizure or electrical failure. The pump simply doesn’t run anymore. On the occasions when I’ve bothered to strip the failed pump, the impeller has been in OK condition.

This is one of my biggest boating frustrations - my wife has become leery about doing any extended sailing because to her, being stuck with an inoperative toilet is just not acceptable.
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Old 20-01-2021, 20:13   #14
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Re: Macerator necessary?

The Jabsco macerator is rated to lift at least 4', so Ii doubt if the 1.5 seconds it takes to lift tank contents to your pump at the top of the tank is enough to cause a problem. Whatever the cause, seizure is caused by components that have gotten stuck together...in turn causing the motor to overheat, resulting in electrical failures to prevent fire. The owners manual includes some "tricks" to get it going again...if you don't have one, you can download it from here Jabsco Macerator Pump owner manual.


Raritan and Johnson Pump have macerator pumps that are higher quality than Jabsco...you might try one of those. The only other alternatives are the Dometic/SeaLand diaphragm pump I mentioned above or a manual diaphragm pump.


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Old 20-01-2021, 20:21   #15
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Re: Macerator necessary?

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If you find one, please post it here.
This one has lasted me 11 years so far.
https://www.defender.com/pdf/503394_BROCH.pdf

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