Black Water Tank Replacement

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   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.

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MasterKeil Members Profile Send Private Message Find Members Posts Add to Buddy List Commander Joined: 08 April 2007 Location: Germany Status: Offline Points: 97	Post Options Post Reply Quote MasterKeil Report Post Thanks(0) Quote Reply 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"

Mark&Catherine Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 18 January 2013 Location: Turkey Status: Offline Points: 1197	Post Options Post Reply Quote Mark&Catherine Report Post Thanks(0) Quote Reply Posted: 27 May 2023 at 08:54
	I can’t empty my tank now (385), and I can’t see how to change the pipe, I can’t 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

Wild Members Profile Send Private Message Find Members Posts Add to Buddy List Rear Admiral Joined: 18 March 2010 Location: Turkey-Greece Status: Offline Points: 639	Post Options Post Reply Quote Wild Report Post Thanks(0) Quote Reply 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. There’s 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 Belgium 545e#268

Keakaka Members Profile Send Private Message Find Members Posts Add to Buddy List Lieutenant Joined: 02 August 2020 Location: New Zealand Status: Offline Points: 37	Post Options Post Reply Quote Keakaka Report Post Thanks(0) Quote Reply 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

Ian2019 Members Profile Send Private Message Find Members Posts Add to Buddy List Captain Joined: 04 November 2019 Location: Montenegro Status: Offline Points: 166	Post Options Post Reply Quote Ian2019 Report Post Thanks(0) Quote Reply 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

Jonw Members Profile Send Private Message Find Members Posts Add to Buddy List Sub Lieutenant Joined: 03 April 2022 Location: Gosport Status: Offline Points: 7	Post Options Post Reply Quote Jonw Report Post Thanks(0) Quote Reply 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

Jonw Members Profile Send Private Message Find Members Posts Add to Buddy List Sub Lieutenant Joined: 03 April 2022 Location: Gosport Status: Offline Points: 7	Post Options Post Reply Quote Jonw Report Post Thanks(0) Quote Reply 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

Martin&Rene Members Profile Send Private Message Find Members Posts Add to Buddy List Vice Admiral Joined: 06 December 2009 Location: United Kingdom Status: Offline Points: 779	Post Options Post Reply Quote Martin&Rene Report Post Thanks(0) Quote Reply 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. https://www.gooutdoors.co.uk/15898440/thetford-aqua-kem-blue-toilet-fluid-2-litre-15898440 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

is46664 Members Profile Send Private Message Find Members Posts Add to Buddy List Lieutenant Joined: 30 June 2019 Location: UK Status: Offline Points: 25	Post Options Post Reply Quote is46664 Report Post Thanks(0) Quote Reply 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

Martin&Rene Members Profile Send Private Message Find Members Posts Add to Buddy List Vice Admiral Joined: 06 December 2009 Location: United Kingdom Status: Offline Points: 779	Post Options Post Reply Quote Martin&Rene Report Post Thanks(0) Quote Reply 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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