Looking for ideas for holding tank size.

Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
I think the problem will be the weight.

I had a Mac 26S -- liked it a lot and a camping toilet.

In my mind, the issue here is the weight.

30 gallons of waste and a toilet and a large freshwater tank all weigh a lot for the Mac.

I remember loading my boat down, once, to the point where water started flowing out the top of the ballast tank... meaning the boat was sinking because was overflowing the ballast tank.

I sealed the top of the tank with the drain plug, and it was okay, but it is something to consider.

Just one man's opinion.
In either of my posts, i did not mean to imply the 30gallon waste tank was a perfect tank size for the boat, but only to answer the question of how big of tank it would take to supply waste storage enough for 4 people for a week:D...

personally, I think the whole concept of a built in waste tank on a boat of this size, type and weight is a poor choice, as almost any other option anyone could choose will be cheaper and easier to use in the long run....

in addition it will take up precious space... we have found that when cruising for a week or more, we have every nook and cranny filled with stuff, (food, water, clothing, 2 ice chests and other recreational gear such as fishing tackle, camera equipment, and cold/foul weather gear, as well as the boat gear that is already there)

some people may not carry as much as we do because like most have said, there is usually a port that they can run into every couple of days for provisions, water or head pumpout/dump....
we do use the dump facilities every 4 days, but as for provisions, the expense of buying them in the islands is at an extreme cost compared to our purchase costs here inland, and then load before we go.

AND, in my opinion with my knowledge in a boat of this size, with all the space taken for a waste tank of that size, there will not be enough room left over for gear space for 4 people for a week. (you may be able to stuff it in, but will have to be shifted every morning and every night and it wont be fun or comfortable in any sense of the word....

I like the porta-pottie set up but have been thinking about giving the wagbag or dootie bag system a try. we did get into a situation at Deer Harbor, Orcas Island, where the dump station would NOT dump my porta-pottie because they said it might contain a formaldehyde base chemical.... this was an unpleasent experience, and instead of another experience like this, I would rather carry the bags up and dump them in the garbage.... (as unpleasant and unsanitary as this sounds, it is supposed to be completely safe and acceptable to do so).
I have also thought about buying a spare bottom tank for the porta-pottie and finding room for it somewhere on the boat so we can be a little bit more independent for a longer period of time....

but worrying about the full tank and what to do with it was the ONLY worry, concern or unpleasant experiance we had in 12 days.... I thought a lot about the bag system that day and how it might work for us:D
 
Nov 22, 2011
1,252
Ericson 26-2 San Pedro, CA
Impossible with any manual or electric marine toilet. Here's the math: the average adult uses the toilet 5x/24 hours...the average flush water volume from today's basic manual or electric toilet is .5 gallons. That translates to 3 gal/person/day. So you'd need an 85 gallon tank to last 4 adults for a week. (Btw, I've prob'ly posted those stats here at least a dozen times over the years...any of you could easily have found them if you'd bothered to look before posting all those wild guesses).

The best solution for a 26' boat is a self contained system...an "MSD" portapotty. "MSD" means it's a model designed to be permanently installed and pumped out...it's not carried off the boat. The 5-6 gallon models hold 50-60 flushes...still not enough to last 4 adults a week, but you'd have to come in after 3 days for water, ice and other provisions anyway, at which time you'd have it pumped out... so it's large enough to meet your needs. Even better, it has no moving parts, so none of the maintenance required for manual toilets and you don't have to give up a major portion of your storage space for a tank and all the related plumbing...although if you're absolutely determined to have a system that'll let you stay out a full week, you COULD install a separate holding tank and redirect the portapotty's pumpout line to dump into it using a macerator pump...but I can't imagine why anyone would want to complicate a wonderfully simpld system by adding the hassle of maintaining the separate tank and plumbing.

There's been quite a bit of discussion of self-contained systems on this forum...easy find if you use the search terms "self contained system" and/or "MSD portapotty"...search 'em out and then check out the Thetford 550 P
http://www.thetford.com/HOME/PRODUCTS/PortableToilets/PortaPotti550PMarine/tabid/884/Default.aspx
This site has some pretty good prices for it too.
I followed Peggy's recommendation and installed a Thetford 550P MSD portapotty when I downsized from a Catalina 30 to an Ericson 26-2. In the C30 I had a conventional Groco head plumbed to a 15 gallon holding tank. Due to the greatly reduced amount of flush water needed with the portapotty, I can go longer without pumping out than I could with the Catalina 30 setup. (On my frequent single handed trips to Catalina I would typically go about 5 days in the C30 but I can easily get a week with the portapotty.) I have it plumbed to a macerator for overboard discharge when 3 miles out and it all works very, very well. No issues with odor, either.

The only complaint is with the cheap, plastic mounting brackets that came with the unit. Once those were replaced with a custom-made stainless one, it's all been good.
 
Dec 2, 1997
8,946
- - LIttle Rock
in all due respect, just so no one gets the wrong idea, there is a couple things here that is not clear....
even so, that a 5-6 gallon porta-potty may have enough fresh water for 50-60 flushes, (depending on how little water you use per flush) the holding tank is only big enough to hold about a quarter of that, with the waste included....
Nope...50-60 flushes is the number of flushes the portapotty manufacturers claim a 5-6 gallon potty holding tank can hold, and it is an accurate claim. That's because the system needs only enough water to rinse the bowl--a pint or even less--or none if only urine goes down...and the user does control the amount. That's about a quarter of the volume from a marine toilet, waste included.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
Nope...50-60 flushes is the number of flushes the portapotty manufacturers claim a 5-6 gallon potty holding tank can hold, and it is an accurate claim. That's because the system needs only enough water to rinse the bowl--a pint or even less--or none if only urine goes down...and the user does control the amount. That's about a quarter of the volume from a marine toilet, waste included.
them pesky salesmen can be so deceiving sometimes, I count a flush when there is something actually being "flushed", not just because someone pulled the handle to see what happens:D
 
Nov 23, 2011
2,023
MacGregor 26D London Ontario Canada
I bet the RV crowd doesn't have great debates like this. Well not this clean anyway.

Thanks Peggy! You have saved me a bunch of time and $. And allot of space on the boat! One of my concerns was the extra weight that a port a potty will add to the Starboard side. The Mac 26D&S are kind of tender even when moving about the cabin. I guess I can compensate for noticed heel with placement of stuff.

I had not thought about the ballast tank over flowing out the vent! I have seen modifications that raise the vent a few inches. I will have to look into that and a automatic bilge pump.

So what is everyone else going to be shopping for on boxing day? I've got my purchases picked....
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
Thanks Peggy! You have saved me a bunch of time and $. And allot of space on the boat! One .
what about all the other contributors to this thread that told you it wouldnt work and gave you the same basic suggestions?:confused:
 
Dec 2, 1997
8,946
- - LIttle Rock
I just noticed that you're in Canada on the Great Lakes. You may run into someone who'll tell you that portapotties aren't legal in Canadian inland waters...that's true. But it only applies to PORTABLE models. Because the "MSD" versions are designed to be permanently installed and fitted for pumpout, they are legal, as long as they ARE securely clamped down and plumbed to be pumped out.

Merry Christmas and Happy Boxing Day!
 
Nov 23, 2011
2,023
MacGregor 26D London Ontario Canada
what about all the other contributors to this thread that told you it wouldnt work?:confused:
I do really respect all the contributors suggestions.

I was out to find a solution to the head problem. My first thought was I should go with a manual type with a holding tank. I also don't have a grasp of the laws regarding the head.
So I started a thread based on a manual pump head and tank...
Peggy's suggestion is the quickest solution to my problem. Also the easiest and cheapest. (I really like those.)
So for $150 I can have a solution that will get me going. (Pun intended.) If I find it isn't adequate I can always go with the manual pump and the holding tank. I'll look at the suggestions here for that info.
The space saving of not having a holding tank is a big factor as there isn't a lot of spots to store things on a Mac 26D/S.
Thanks all who have contributed!
Finding