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Old 30-01-2012, 22:15   #1
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Macerator Between Head and Holding Tank

We recently chartered a Catalina 375 in Australia. It had an electric head that, unlike any head I had ever seen, ran the macerator as a part of the flush process and pumped the result to the holding tank. Emptying the tank simply involved opening the seacock, whereupon the stuff just drained out due to gravity.

I thought this was a really fine idea, particularly because I ended up with a stomach bug during the trip that required frequent use of the facilities. Given the immediate maceration, I was a lot less worried about clogs (due either to paper or organic material) than I might otherwise have been. The gravity drain seemed to work fine for ultimate disposal although I suppose that less than regular disposal could cause some problems.

I assumed that this was just a new feature of Catalina's 355/375/385/445 line but I recently toured the 385 at a boat show and the broker was pretty sure that the boat had the more traditional setup with maceration as a part of the dump process.

So my questions are: 1. Is maceration as a part of flush the new wave of the future or just an Australian anomaly? and 2. What does anyone think about which process is better?
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Old 30-01-2012, 22:55   #2
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Re: Mascerator between head and holding tank

G'Day mate,

It's a Queensland aberration! Local rules in that state allow overboard discharge in many areas, but only if the effluent is macerated (down to some specific particle size... dunno if anyone has ever chased one down to measure it!). Thus, many Qld boats are set up just as you have described, though not all have been clever enough to have gravity discharge from the tank.

Cheers,

Jim
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Old 31-01-2012, 09:02   #3
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Re: Macerator Between Head and Holding Tank

Some electric heads have integrated mascerators. Our Jabscos do.
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Old 31-01-2012, 10:48   #4
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Re: Macerator Between Head and Holding Tank

No...it's not the "wave of the future."

Adding a macerator pump inline between a manual toilet and tank or thru-hull is a bad idea...because macerator pumps move material at about 12 gpm, which pumping a manual toilet cannot come close to matching...with the result being repeated "fried" impellers in the macerator pump. Replacing the manual pump with a macerator pump is a VERY poor excuse for a macerating electric toilet. It'll work, though although it'll pull water in at the same 12gpm rate it's pulling bowl contents out, which fills up a holding very quickly, and it also has a very short lifespan. But it's cheap--only about $150, compared to $300-$700 for a real macerating electric toilet--so it's not surprising that you find one on a charter boat...toilets are the biggest problem on charter boats. That's why they all use Jabsco manual toilets...because they're the cheapest. However, Jabsco macerating electric toilets cost as much as those that are much higher quality...which is why charter companies rarely install electric toilets.

Btw...your stomach bug had already done a better job of "macerating" than any macerator pump. Adding water to the bowl ahead of use (why does it never occur to anyone use a cup from the sink to do that???) would allow a manual toilet to work without clogging on TP.
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Old 31-01-2012, 11:43   #5
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Re: Macerator Between Head and Holding Tank

Guess I should have been more specific. The boat we chartered had an electric head, not a manual pump. If I recall correctly, it pumped sea water from a through-hull rather than fresh water from a tank (although I am not sure that makes any difference to this issue.) The relevant difference between this setup and other electric heads I have seen was that the macerator was in the head pump rather than in a separate pump between the tank and the exit port. The stuff gets macerated either way but it seems to this very inexperienced sailor that macerating before the tank is less likely to result in clogs than transferring it to the tank and letting it sit around there in its original configuration until it is possible to pump or dump it out. Thoughts?
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Old 31-01-2012, 12:15   #6
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Re: Macerator Between Head and Holding Tank

If I have it straight, what I think you're saying is, there was a bowl..then a macerator pump installed downstream of the bowl. That suggests to me that the toilet started life as a manual toilet, but was "converted" to electric by removing the manual pump and replacing it with the macerator pump as I described above.

The tank emptied via gravity, so there was no pump in the TANK discharge line. The Aussies require that only macerated waste can be dumped...so the arrangement on the boat you chartered was the only way it could comply with the law without either replacing the toilet with an expensive macerating electric toilet or installing a macerator in the tank discharge line, which would have required quite a bit of replumbing.

Fwiw, solid waste is at least 75% liquid, a stomach bug make it as much as 95%...and even a manual pump breaks it up...so it dissolves fairly quickly in water anyway. And so does quick-dissolve TP--the kind that practically dissolves in your hand if it even gets damp. So nothing stays in its "original configuration" in the tank very long, if at all...making maceration really unnecessary. Otoh, the Aussies only require boats to be ONE mile offshore to flush directly overboard or dump a tank and their real aim is to keep the stuff that couldn't make it through a macerator pump without jamming it off the beaches...and this seems to accomplish that.

But I wouldn't recommend it on your own boat...in the long run it'll cost you far more than a true macerating electric toilet.
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