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Black Water Tank Replacement

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MasterKeil View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MasterKeil Quote  Post ReplyReply Direct Link To This Post Topic: Black Water Tank Replacement
    Posted: 27 May 2023 at 17:28
Thats it Ian2019. When my waste tank was depleting slowly, I found this wire cage blocked by bugs and debris. After cleaning the mesh the depleting rate is back to normal.
Hanse 370#640 "Nemesis"
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Mark&Catherine View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark&Catherine Quote  Post ReplyReply Direct Link To This Post Posted: 27 May 2023 at 08:54
I canít empty my tank now (385), and I canít see how to change the pipe, I canít reach the jubilee clips on the hose at the bottom of the tank. Has anyone managed to change the pipe ? 
385 ubulukutu sail number GBR 3350L in Turkey and Greece with Mark and Catherine
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Wild View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Wild Quote  Post ReplyReply Direct Link To This Post Posted: 07 May 2023 at 07:57
After to much issues with Wurth blackwater tanks I made a manhole controller hole just on top of the riser tube so I can clean the tank easy and make a SS tool (you can see it in front of te tank) to clean the rising tube from above. The rising tube is the most critical of the tank. Thereís always black water in this tube (tank empty our not) And in a warm environment and salty waters this tube get easily blocked with salt- and urinecristals.
The filter in the ventilation cap is stupid. Throw it away.
 



Edited by Wild - 07 May 2023 at 08:03
Wild and Wet
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Keakaka View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keakaka Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2023 at 09:15
I found it is useful to pour 5 litres of water into the deck connection when dumping the tank contents. The extra pressure pushes some of the blockage material out through the seacock. Guests always use too much paper and not enough water. 😥
This is not a rehearsal. Go for it. Kiakaha
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Ian2019 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ian2019 Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2023 at 04:27
There is a small wire mesh filter in the side hull vent to the holding tank and the filter gets blocked, therefore not allowing air into the tank when draining so a slow drain. I took mine out ages ago and have had no problems.
H385 #317 2014 Tivat Montenegro
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Jonw View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jonw Quote  Post ReplyReply Direct Link To This Post Posted: 04 May 2023 at 13:45
Hi All - a short update on this (for info)

(My 385's problem was the holding tank not draining / draining v v v slowly)

I disconnected the 'exit pipe' which runs from the holding tank to the seacock, from the seacock end.
(I couldn't get access to the jubilee clips on the end at the actual holding tank to undo the other end)

The pipe itself was clear, no scale, no blockages, I rodded it to make sure.

I then wondered if there was scale (calcium carbonate) inside the holding tank.

So I poured in some hydrochloric acid (patio cleaner) and it 'fizzed' incredibly, indicating it was having a strong reaction with something in the tank, probably calcium carbonate. 

I attach a photo.

The level of sea water in the tank is marked by the (low down) blue dots.

The 'fizzing' is marked by the higher up black dots. At times the fizzing reached the metal band and above.

I repeated this process a number of times, until there was no more fizzing when I poured in the hydrochloric acid.

At that point, the tank would drain incredibly fast, and (so far!) reliably!

We've also just had a long weekend on the boat, with multiple people on board utilising the facilities, and all has so far behaved very well, and the tank continues to drain v v fast when set to empty.




Also (for info) when 'rodding' the pipe, it appears that there may be an 'elbow' just inside the holding tank, like a 90 degree turn. (my conclusion based on rodding)

I hope this info may help others in time.

In other news, we had a very lovely few days sailing around the Solent, in light airs, which were just perfect for a shakedown sail / first outing of the season.

Wishing you all happy sailing.

Jon
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Jonw View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jonw Quote  Post ReplyReply Direct Link To This Post Posted: 16 March 2023 at 17:16
Thanks, this is all really useful.

For info, I've checked from outside the hull that there is no blockage, I setting an implement which went in easily.

And I've checked there's no vacuum (there is not)

So I think my next step is to remove and replace the pipe from the tank to the sea cock.

I'll also check which side this comes out from!

Thank you for all of your help

Jon
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Martin&Rene View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Martin&Rene Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2023 at 17:42
As you say, it certainly does not look like  the best design of tank.  Just looked at one of my catalogues and all their plastic holding tanks have a top inlet rather than using an internal riser pipe.

I do not know whether a procedure change may help the situation.  If the tank is full, I try to delay emptying it until we are in choppy water.  I pump the toilet at least 15 times, then open the seacock to empty the tank and keep on pumping the toilet until I think the tank is empty.  The aim is to stir up the contents of the tank as much as possible, so that there is minimal sludge left in the tank at the end.

On my boat, I also have a bottle of the toilet chemicals that the caravan owners use to liquify the waste in their cassettes.  


So far I have never needed to use it.  It could be something you could try using on a regular basis to stop the blocking.

Final point, are you sure everybody abides by the toilet rules.  I have very strong (smelly) memories of being in Turkey with the temperature over 40deg C and having to take the plumbing totally apart on a Halberg Rassy, because the owner's son had forgot to tell his girl-friend not to put sanitary products down the loo. 

Jon   I would send KNick a private message.
Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland
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is46664 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote is46664 Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2023 at 18:14
At first I thought there was no riser but you are correct the tank has a riser

Edited by is46664 - 13 April 2023 at 09:19
Ian Stevenson
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Martin&Rene View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Martin&Rene Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2023 at 15:57
I thought all holding tanks were designed with a riser as shown in the diagram of the Wurth holding tank, otherwise, when the joker valve leaked (as it will do at some time) then all the contents of the holding tank would discharge back into the toilet and overflow.  Not a pretty thought.  In the standard layout, when the joker valve leaks, only the contents  of the pipe come back to the toilet.

One simple test.  Pump water into the holding tank.  If the water enters at the bottom, then there will be little noise.  If it enters through a riser, then you may hear the water fall from the top of the riser pipe. 
Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland
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