Larger Holding Tank for Catalina 34 MK II

[Fred Koehlmann]

Sorry if this appears as a double post. I got an error posting suggesting that I had already, but I did not see the post on the forum.
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Our first season is unfortunately windling down and while it was a wonderful experience we have as expected developed a list of enhancements/fixes that we want to address. We sail on Georgian Bay (Great Lakes Area) and will often go for extended periods away from any marina and we find the 18 gallon holding tank a bit small for four people (two adults and two kids). If we invite guests, it feels even smaller. So increasing the tank size is one of our top enhancements we want to address.

I've requested info from Catalina about getting a larger holding tank and they recommended the 30 gallon tank from Ronco (number 60170 or Ronco-B179 http://www.ronco-plastics.com/newRonco/product_details.php?prodID=72) versus the Ronco-B212 (http://www.ronco-plastics.com/newRonco/product_details.php?prodID=104) that we currently have. Apparently the C34 MK I's are suppose to be outfitted with the larger tank (or so I was told). I've done some preliminary measuring and noted that my thru-hull for the macerator would be in the way, plus the deeper dimension on the port most side of the tank seems to a bit tight. I am wondering if anyone else has done this upgrade to their MK II and how did it go? How did you deal with the thru-hull and did it sit properly within the available space?

I found a thread started by Hank Toby in 2003 and an even older one from 2002 with no apparent resolution. In 2007 I see Chris Martinson asks a similiar question, but for a MK I. I don't expect to many coastal sailors doing this upgrade, but anyone in freshwater might have.

The attached image shows the existing B212 tank and the thru-hull location. The new B179 would be almost as big as the storage locker's opening, thus cover the thru-hull.

[cmainprize]

Hi Frederick

I think we may have met over the summer around cedar springs?  Your post is interesting to me as I also find our factory tank too small.  We also cruise with two adults and two kids.  My intetention was to covert our aft water tank to holding this winter to increase our holding tank size.   I pulled the aft tank last year with the intention of doing the conversion this spring but ran out of time.  But if the 30 gallon tank from ronco fits in the factory location I will be ordering it Monday.  I will measure this weekend, if it fits through the locker opening it will be perfect.  I do not have a through hull located in this locker, but I would not worry about removing it and filling the hole.  Easy and cheap to fill the hole. 

Thanks for the post, you may have saved me work and bought me an extra 5 days between pumpouts.

Cory

[Peggie Hall]

Fred...you said, "I've done some preliminary measuring and noted that my thru-hull for the macerator would be in the way,..."

You can't use a macerator pump on the Great Lakes, so there's no reason to avoid covering up the thru-hull. If the seacock etc are in the way, remove the thru-hull and have the hole glassed over.  If you or an FO (future owner) ever take the boat offshore where a macerator would be useable, a new thru-hull in another location can be installed.

And as long as you're replacing the tank, now would be an excellent time to relocate the vent line OUT of the rail stanchion and into a thru-hull that will allow you to back flush it to prevent it from ever becoming blocked.

[Jim Hardesty]

I rate the small holding tank, really the entire waste system, as the worst system on my boat.  The specifications say 18 gal.  It might be to the top.  But due to the tank shape (narrow at the bottom) I don't think that the usable volume when sailing is 12 gal.  When we are out cruising, just my wife and I, it's a pump out every 3ed day or so. 
Well my rant is over. 
After all that, needless to say that I'm very interested in upgrading the holding tank and will be following this thread with anticipation.
Jim

[Fred Koehlmann]

Cory: Yes, I remember seeing Mystic around Beausoleil Island. I think you gave Kathy some sailing magazines that you had already read (we're still not finished reading them... life's so busy). You mention you do not have a thru-hull in the port locker. Is Mystic not a MK II or did you have it already removed? I'd be interested in how your measuring compares to mine. I felt it still seemed a bit tight on the outboard (port most) side.

Peggy: Yes, the macerator is pointless for us. We store it in our dock-box and are only holding on to it incase we ever sell the boat in the future, which was also why I would prefer to not to remove the thru-hull... but if I have to, then I will.

With respect to the vent line, that is one part of what we need to take care of. That stantion is leaking at the deck and the water makes its way behind the electrical panel. My plan is to remove the stantion, cut off the thru-hull vent fitting off, epoxy the holes and reseat the stantion. I then plan to vent forward out the hull behind the port v-berth locker just below the deck. We'll see if I can fit in your recommended 1" or larger line.

A second part of this upgrade would be to reroute the inlet from the head to the tank. Currently it goes from the head aftwards under the sink, then loops up and forwards behind the head, past the hanging locker and nav station and down into the tank. I measured that this is approximately nine feet long. I want to redirect the flow from the head directly foward and up and then down to the tank (about five feet only), thus removing the aft loop. I actually don't understand why the plumbing was routed the way it was, unless there is a need to have the head exit horizontally before it goes up?

[Peggie Hall]

A couple more possible plumbing changes: 1. When you specify the tank fittings locations, put both the inlet and the vent fittings alway from the hull, toward the centerline...that will prevent waste from running back into the head discharge hose and/or spilling out the vent when the boat is heeled. 2. You'll need a vented loop in the head intake. And, it MIGHT make sense to put a loop--not necessarily vented--in the head discharge line so that gravity can assist in getting the bowl contents to the tank.

I'll be glad to brainstorm the whole installation with you if you'd like to email me.

[Fred Koehlmann]

Hi Peggie,

Thanks for the suggestions. I understand the idea of locating both vent and inlet more inboard, but I'm not sure that will work with the inlet, because of how it enters the compartment. It would need to make a fairly tight (almost 90 degree) turn (see existing inlet in image above). Hopefully a high enough loop will compensate for that, as per your second suggestion.

I'm not sure that I understand the need for a vented loop in the head intake. The water intake originally went directly from the thru-hull inlet to the head's pump, then from the pump via a vented loop to the bowl (which actually didn't make any sense to me). When our head had flushing issues this spring our marina tried to sell us a new head, but I went for only replacing the pump assembly (including joker valve) since the bowl was just fine and well seated and the new pump had a locking feature. At that point the head had a hose that went directly from the pump to the bowl, so I just disconnected the vented loop and left it hanging in place for now. We usually close the seacock when sailing.

I'd be glad to take you up on your offer once I'm confident that the tank will fit. I'll be going up Sunday to do some final in water prep before having the boat hauled out for the winter, so I'll recheck my measurements. We unfortunately have cut our season short because our youngest broke a leg and for now needs constant supervision.

[Peggie Hall]

I'm not sure that I understand the need for a vented loop in the head intake.

It's very simple. Water seeks its own level...and when the toilet is at or below the waterline, water outside the boat seeks its own level INside the boat via the toilet intake line.  Priming a manual or electric toilet actually starts a siphon that needs to be broken, which is one of the functions of a vented loop. Without an anti-siphon device, sea water would just keep on coming in.  The loop also puts an arch in the line that's far enough above the waterline to prevent just simple level-seeking to happen.

Now, you're gonna argue that you keep the seacock closed when underway...but humans are fallible. Can you always count on any crew or guest who needs to use the toilet while sailing to close it? Can you even count on 'em--or yourself--to ALWAYS be sure to leave the toilet in the "dry" mode?  Do you religiously close ALL your seacocks when leaving the boat?   What guarantee do you have that the wet/dry valve won't ever fail?

The answer to all those questions is no...you can't.  A vented loop in the intake is a failsafe that protects your vessel from human fallibility.  And it belongs between the pump and the bowl, NOT in the line between the thru-hull and the pump. Why?

The pump PULLS water from the thru-hull TO itself...the air valve in a vented loop opens to pull air into any line through which water is being pulled, preventing the pump from priming.  But the pump PUSHES water from itself to the bowl...and siphon breaks don't interfere with water being pushed through a line. So the vented loop needs to be where it won't prevent the pump from priming, but will still break the siphon started by flushing the toilet.

Toilet mfrs just connect the pump to the bowl with a short piece of hose because vented loops are only needed in below-waterline installations, which is only about 50-60% of 'em.  Your toilet is below the waterline, so you DO need the vented loop.  So reconnect it, ok?

[cmainprize]

HI Fredrick
Yep that was me who gave your wife the magazines, sorry to hear about your childs injury.  The rule at our house is no injuries, funerals or weddings when the boat is in the water.

Our boat is a Mk11, but it does not  have the macerator through hull, the tee is in the line and the wiring is in place but no through hull.  Your right about the hose being much longer then it needs to be because it loops around under the sink prior to going forward to the tank.  I replaced the hose this year and it was 10.5 feet long.  I thougth about haveing the hose discharge go directly forward but then I would need to drill another big hole and have an unused hole in the head.  So many choices. 

It's hard to tell from the drawings on the ronco site if the tank will fit.  I think the only way to be sure is to make a mock tank and see if it will fit.  We are in the water still for a couple more weeks but when we come out I am going to build a mock up and see if it wil fit.

Cory

[Roc]

Frederick,
My boat also came with the hose routed aft, then looped forward to the holding tank.  Don't know why Catalina did that because it add so much unneeded hose.  I changed it by drilling a hole into the hanging locker and routing the hose forward, directly to the holding tank.  I believe there is an elbow at the bottom of the pump that is pointed left (aft).  Just unscrew it and spin it around to face forward.  You'll get an idea where to drill the hole at that point.  Then install the hose by pushing it through the drilled hole from the hanging locker, mating up with the elbow.  Connect the other end to the holding tank and you're done.  The hose simply runs along the bottom of the hanging locker.

[Stu Jackson]

Roc & Frederick,

That's exactly how the Mark I boats were done, least mine is.

[John Langford]

An alternative is to drill a 1 1/2" hole directly behind the Jabsco pump outlet and then lead the line up and through the original cutouts across the back of the hanging locker. I have done this successfully and the hose run is almost exactly 5 feet. It also allows you to create a loop in the hose as Peggie suggests before it runs down to the tank inlet fitting. And, finally, it preserves all the needed space in the hanging locker.

Peggie, the MKIIs already have a vented loop between the pump and the bowl. At least mine does.

I found a neat 3/4" fitting the other day which is 90 degrees with a stainless steel cover on the outside. If you insert it through the hull just below the stanchion presently used for venting the tank, you can use the existing vent hose without rerouting it out of the electrical panel area.

PS I also doubt that the existing tank is 18 gallons but I confess that I haven't got the courage to confirm that:)

[Ralph Masters]

The booklet says the tank on my 87 is 23 gallons.  Not sure how you'd go about confirming that.
Of course the inlet is not in the top, so you loose about two inches of space inside that way.
So maybe it is a 23 gallon tank but you can only use 18 gallons of that space.

Ralph

[Peggie Hall]

Peggie, the MKIIs already have a vented loop between the pump and the bowl. At least mine does.

That means that Catalina actually installs vented loops where needed...many boat builders don't.  However, you'll never find one included when you buy a new toilet, it's a fitting you have to buy if you need it.

[Mike and Joanne Stimmler]

A sailor friend put a ball valve in that spot in place of the vented loop which works OK but you still have to remember to close it.

Mike