Holding Tank Question 2004 B36

[Querencia]

I am a new owner of a B36 this summer in and one thing the PO said is that he had changed all the hoses to the head and holding tank, I was wondering if there is a one way valve that is missing from the hose that goes  from the bottom of the tank to the thru hull, I go offshore frequently  and decided to dump my holding tank, the thru hull had been closed,When I opened the thru hull, only half the tank emptied to the level of the water line, that make sense that it did that but how would I empty the tank completely without a pump ? 

[Lyra]

This seems wrong - I have the same boat and the bottom of the holding tank is well above the water line - I have the model where the heads are next to the bow cabin.

[Querencia]

I have the two cabin version where there is a large forward cabin, a large aft cabin on the aft port side and the head is on the starboard aft with a wet locker and large very deep larzerete , the holding tank mounts upright in the larzerrete  on the head/wet locker wall, most of the 3 cabin versions were charter boats, horizon yacht charters had a whole fleet of b36's  in the Caribbean   Ed

[Salty]

Like Lyra I have a three cabin B36 from 2002, and the bottom of the holding tank like his is well above the waterline. On my boat however the holding tank has no plumbing attached to it, making it nothing better than a bulky ornament hidden behind a cupboard door. I'd like to make it functional, but does anyone have a plumbing diagram to show what should be connected to where, and preferably with some indications of sizes?

[Lyra]

I'd like to make it functional, but does anyone have a plumbing diagram to show what should be connected to where, and preferably with some indications of sizes?

Assuming you do not look for a Y type diversion of the flow, the plumbing is very simple since the holding tank is merely a "wide section" of the outlet hose - This is how it is in my boat. When at port the seacock is closed and everything is held by the tank and when in open water it is open and the tank discharged.
The outlet hose from the toilet bowl goes to the top of the tank. The outlet (bottom) of the tank goes to the outlet seacock. Hose diameter is the same as you currently have. I guess you will be able to use the current hose for the tank-seacok section and just need to buy a new section for the toilet-tank section.
If not already installed and if you need it, then there is another hose that needs to be installed for pumping out the tank - but this will require drilling in the deck and dis assembly of the tank. 
I do not remember that there is a vent hoze, but probably there is one - will have to look next time on the boat.

[Salty]

Many thanks Lyra, that's very helpful and sounds simplicity itself to install. I guess there will be a vent fitted somewhere to prevent over or under pressurisation of the tank depending on whether you're pumping in or draining out. In regard to emptying the tank to sea, do you have a separate pump for that or does gravity take over and sort it all out ?

[Lyra]

Gravity - tank bottom is well above the water level

[suibhne]

I have a similar two cabin boat.
Tank should fully empty when valve is opened.
Care must be exercised with a non-macerated tank like mine so as not to block exit pipe.
A reason for incomplete empty or slow drain might be partial blockage.
To resolve the problem get a stiff bit of tubing and inserting tube in the general direction of the exist pipe  and try to clear the blockage.
Not a task to look forward to but then as they say
'Nobody said it would be easy'.

[dawntreader]

......A reason for incomplete empty or slow drain might be partial blockage.
To resolve the problem get a stiff bit of tubing and inserting tube in the general direction of the exist pipe  and try to clear the blockage.
Not a task to look forward to but then as they say
'Nobody said it would be easy'.

Back flushing with a running hose is an effective way to clear blockages (use a piece of cloth wrapped around the hose to block the exit hole). Also, flush through the air vent as this can also become clogged and cause incomplete clearance.

[suibhne]

"Back flushing with a running hose is an effective way to clear blockages"

Not sure about this in case of a holding tank
I think this is the reason that some marinas in the South of England have removed  hoses from their water outlets

[Lyra]

From the original post this does not seem to be a blockage problem.
A full blockage would have prevented any discharge.
A partial blockage would slowly but surely drain everything out.
The fact that it drops to a certain level, which seems to be the same level as the water line, implies that the tank is located too low.

[Querencia]

That is my opinion , that the tank is mounted too low, but this is the location that the tank was mounted either from the factory or the Bavaria Distributor, I could remount it a little higher, say 6 inches but that still wouldn't solve the problem of part of  it being below the waterline,I would say right now, the top of the tank is 40 % above the water line, Oh Well ,At least I know that the tank isn't clogged ,The two cabin version of the B36 has a very deep lazerette on the starboard aft , probably close to 5 feet deep , Thanks to everyone who has responded so far
Ed Pinanski
"Querencia "
2004  B36
Beverly,Ma [ North of Boston on the coast ]

[The Other Woman]

Hi All
Is there any photo's of the holding tank and location for a Bavaria 36 holiday 3 cabin? I was thinking of fitting one over the winter (that is gravity fed) somewhere behind the 3 little cupboards in the heads rather than in the cabin wardrobe.

Mick

[dawntreader]

Just for clarification    :

"Back flushing with a running hose is an effective way to clear blockages"

Not sure about this in case of a holding tank
I think this is the reason that some marinas in the South of England have removed  hoses from their water outlets

The 'back flush system' works perfectly well for me!
Also, hoses are removed because the water companies are concerned about the possibility of Legionnaire's disease and/or back-siphoning.

 

A partial blockage would slowly but surely drain everything out.

A partial blockage will not 'clear slowly'. This was the issue I had. The gravitational force is reduced if the air vent is inhibited and will not allow the tank 'solids' to clear properly.

[MarkTheBike]

Hi Querencia

Regarding your OP, if you can get to the hose from the bottom of the tank to the seacock and there's enough space, it is a doddle to fit a pump. They are simple to wire up and would get over your problem of raising the tank or having it stay half-full. If you're not handy with a toolbox, it should be a straightforward task for a marine mech. 

[Lyra]

Salty - Took some pictures today of the plumbing that may guide you.
1. top of tank - hose from the toilet bowl and vent hose - the vent leads to the port side of the anchor chain holding, just next to the platform holding the windlass. There seems to be a sender for the level, but I see no wires coming from the distribution panel to this area (there seem to be 2 LEDs ready for 2 holding tanks indicating 3/4 level full)
2. Hose to the deck for pumping out
3. Hoses at bottom - one goes to the seacock and one to the pumpout.

[Salty]

Many thanks Lyra, the pictures are very helpful as also the description of where the vent is lead to inside the chain locker. In picture 1, there appears to be a large circular area, not all of which is visible, but would that be an access hatch to the tank, perhaps to enable cleaning? The top of the tank on my boat is out of sight where it is above the lower edge of the top of the access door to that space, and up to now I've never wanted to look at it. I'm going over to the boat tomorrow, so will take a small camera with me. There is just enough room for me to get my arm in with the camera to photograph the top of the tank, so I can get to see what is there.

[Lyra]

Yes this is an access hatch - because of the limited space above it I would say it will be useful only in cases where everything else fails.