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Heads/holding tank plumbing on 312

Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 311 / 312 / 315
Forum Description: 311 / 312 / 315 Hints and Tips
URL: https://www.myhanse.com/forum_posts.asp?TID=14779
Printed Date: 27 March 2026 at 03:51
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Topic: Heads/holding tank plumbing on 312

Posted By: Theoldcodger
Subject: Heads/holding tank plumbing on 312
Date Posted: 16 August 2024 at 21:46

I am a little confused over the Heads plumbing on my 312.

I have two "seacocks" - one clearly is the sea water supply to flush the loo. The other I think is something to do with the holding tank but what its actual function is I am not sure. To add to my concerns it has jammed this season ( and will need repair/replacement). However I can still flush the heads with the outgoing water going straight to sea I assume.

Can anyone clarify the plumbing arrangements and perhaps send a "plumbing diagram".

Very many thanks - Julian ISOTOPE 312.

Replies:

Posted By: Martin&Rene
Date Posted: 25 August 2024 at 13:07

The normal arrangement is that there is a seacock on the seawater inlet pipe to the pump. After the pump and the toilet bowl, the fluid is pumped up into the holding tank. The pipe either enter into the holding tank at the top of the tank or it may enter through the bottom of the tank and there is a riser pipe in the tank, so that again the fluid enters the tank at the top. Thus when the joker valve leaks, only the contents of the pipe come back into the toilet bowl.

There is then a pipe from the bottom of the tank, which goes through a seacock (normally a larger one) before discharging into the sea. The purpose of the second valve is that when you are in a nice anchorage, you can shut the valve and the toilet discharge is held in the the tank. You can then either open the valve and empty the tank when you are far offshore, or you may also have a pump-out outlet in the deck for use in a few marinas.

Presumably, your valve has been stuck open, with discharge straight to the sea..

Take care if you do start using the holding tank, as its capacity is very small

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Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland

Posted By: perry
Date Posted: 25 August 2024 at 20:19

Hi Oldcodger,

there is a possibilty you have a similar Holding tank plumbing to my last Hanse a 301. It was most odd and a little dangerous. The toilet waste /holding tank was a 1.5 " skin skin fitting with a bronze valve which had a change over configuration . Move the valve 90 degree one way and the toilet exited to the sea, and and it blanked the pipe from the holding tank. Move handle 90 degree and it blanked the toilet and sent the toilet waste up into the holding tank.. So one way dumps from toilet to sea, and shuts of holding tank, other way shuts off sea and sends toilet to holding tank. The problem is that the valve seized half way and in the event of a pipe fail there is no way to shut off sea?.

I fitted standard on/off seacock and a jabsco diverter valve to correct the dangerous design.

Note my current Hanse 315 [2007] has system that pumps all waiste to top of holding tank, the bottom pipe of holding tank goes to standard seacock. That means all toilet pumps up to holding tank, and seacock emptys the tank to sea. Yes holding tank has a tube and deck mounted fitting to vacuum out the waiste to a dockside pumping facility

Perry

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Current Yacht Hanse 315 2007
Last Yacht Hanse 301 Round GB in 2017

Posted By: Theoldcodger
Date Posted: 03 September 2024 at 18:46

Thanks so much for your reply - very helpful. I think you must be right as presently I flush the sea toilet in the usual way and all is good. As my season is drawing to a rapid close. I will leave the larger seacock where it is until the boat is ashore, and properly have it sorted then.

Apologies for not replying sooner, I missed the two messages coming in.

Thanks again - Julian ( Isotope)

Posted By: Theoldcodger
Date Posted: 03 September 2024 at 18:49

Thank you Perry for your reply too. As I said I will leave all as is for the time being until my winter lift out.

As a matter of interest where on the IOW do you keep your 315. I am at Northney on Hayling Island...and a regular across, and up and down the Solent. ATB Julian ( Isotope)