Looking for recommendations for Porta Pottie with MSD

Nov 22, 2011
1,227
Ericson 26-2 San Pedro, CA
That AMazon listing has been up for years...and while it's listed as the MSD version, it's actually the portable version. You won't find either version on the Thetford site.
--Peggie
Interesting about the Amazon listing. Wonder what's up with that.

Several listings for the 550P MSD can be found on eBay right now....
 
Dec 2, 1997
8,864
- - LIttle Rock
Several listings for the 550P MSD can be found on eBay right now....[/QUOTE

I just checked them out. There is only one that's definitely the MSD version...the listing includes a schematic that shows the "pumpout kit." You'd have to contact the sellers of the rest of 'em and ask 'em. Without it, they're portable version.

It's not surprising to see portables listed as the MSD version by sellers who don't stock much if anything to do with sanitation because the legal definition of MSD “includes any equipment for installation on board a vessel which is designed to receive, retain, treat, or discharge sewage, and any process to treat such sewage," so they just assume that all portable toilets are MSDs.

So be careful when looking for anything--not just portapotties--when shopping for discontinued equipment 'cuz a lot sellers, especially on ebay or Amazon 'cuz a lot of seller know almost nothing about the things they sell. In the early days of ebay I used to see "new in box" that had been sitting unopened in the box for 10-20 years!

--Peggie
 
Oct 31, 2022
69
Catalina Capri 22 Huntington
So what do people recommend? Reading through this I'm not sure I know which one to go with my self. Looking to add a MSD to my Capri 22. I may buy on amazon and see how it comes. If its not an MSD I can just return it. . .
 
Dec 2, 1997
8,864
- - LIttle Rock
Thanks to a li'l gizmo called the Uniseal UNISEAL it's a fairly easy job to turn a portable potty into an MSD version. You only need to be a little bit handy with a hole saw--or have a friend who is-- and buy a little schedule 80 PVC pipe that has the same OD as the ID of your pumpout hose (most likely 1.5"). Detailed instructions on request.

--Peggie
 
Oct 31, 2022
69
Catalina Capri 22 Huntington
Thanks to a li'l gizmo called the Uniseal UNISEAL it's a fairly easy job to turn a portable potty into an MSD version. You only need to be a little bit handy with a hole saw--or have a friend who is-- and buy a little schedule 80 PVC pipe that has the same OD as the ID of your pumpout hose (most likely 1.5"). Detailed instructions on request.

--Peggie
I am handy with a hole saw, so which non-MSD potty would you recommend to convert?
 
Dec 2, 1997
8,864
- - LIttle Rock
Pick the one you like best...not necessarily "marine"...that'll let you drill a couple of holes--one for the vent and one for a discharge fitting--at the top of the tank. You'll put a diptube on the pumpout fitting. Check out the RV market...there are some "cassette" potties that are actually quite nice.

--Peggie
 
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Oct 31, 2022
69
Catalina Capri 22 Huntington
I purchased the Thetford on Amazon. Will see if it is actually the MSD version. If not, free return back to amazon.
 
Oct 31, 2022
69
Catalina Capri 22 Huntington
Ok, so the Thetford 550p MSD on Amazon IS the MSD version! It came in the mail today. Looks like a good unit. My problem now is that it doesn’t fit perfectly in a little area that Catalina made in the floor for a Porta Potty. I am struggling a little bit on whether to start cutting/trimming/maybe just grinding a little bit? into the floor for it to fit or to return this and look else where. I think I will only have to cut into the corners a little bit. Hmm
 

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Sep 24, 2018
3,043
Catalina 30 MKIII Chicago
Ok, so the Thetford 550p MSD on Amazon IS the MSD version! It came in the mail today. Looks like a good unit. My problem now is that it doesn’t fit perfectly in a little area that Catalina made in the floor for a Porta Potty. I am struggling a little bit on whether to start cutting/trimming/maybe just grinding a little bit? into the floor for it to fit or to return this and look else where. I think I will only have to cut into the corners a little bit. Hmm
Thanks for the confirmation on the model. I'd put a plastic board over that hole in the floor. G10 would also work but it might be a bit pricey
 
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Oct 31, 2022
69
Catalina Capri 22 Huntington
I am considering a board under the toilet but I am concerned with how high it sits. There is a board that goes over that section so the v-birth cushion can lay on top of that. I think the two may interfere. We will see.
 
Sep 30, 2013
3,562
1988 Catalina 22 North Florida
I realize I'm late to this party, but if I can stop anyone from buying the Thetford 550P, I will. We've had one for several years and it works fine, but IT WILL go tumbling around your cabin like a BB in a boxcar, if you don't make your own hold down brackets. Which is not as simple as it sounds.

I resent Thetford, because they have known about this critical weakness for years and years and years, and done nothing about it. They simply don't care. So, I will divert business away from them whenever I can.

The Dometic 965 MSD is slightly less elegant to look at, but it is built sturdier, and the hold down brackets are bomb proof. I own its little brother, the 964 MSD, which is identical except it has a smaller 2.5 gallon holding tank. It is therefor short enough to fit under the C22 V berth, if that is something you care about.

I have no experience with the Sanipottie 975, but I distrust the way you are supposed to pump air pressure into it, and then push a button to flush it. Why? This design is unnecessarily complex. Not a characteristic I want, in a device that contains a week's worth of human waste.
 
Sep 24, 2018
3,043
Catalina 30 MKIII Chicago
I distrust the way you are supposed to pump air pressure into it, and then push a button to flush it. Why? This design is unnecessarily complex.
Marketing I suspect. I believe they claim you can get a couple of flushes out of X number of pumps. Either way I had multiple failures on this unit. I suspect lake water may have clogged some passages in mine. Regardless, I will definitely do some research on this model. I very much appreciate your recommendation!
 
Sep 24, 2018
3,043
Catalina 30 MKIII Chicago