A question about heads.

T

Tinto

Well-Known Member
Joined
25 May 2019
Messages
220
Visit site
Hi All
After months of searching I eventually got my boat and I am learning g quickly that boat ownership and seamanship are very different things.

lots of problems to be fixed and many fixed already.

but I have a question about sea cock and heads.

should all sea cocks below the water line have an anti syphon loop?

This morning I woke up to find stuff in the heads that wasn’t there last night. Not what you want to see at anytime but definitely not first thing in the morning. Yesterday I was looking at the header tanks for that heads and gave a few pumps to the manual evacuation pump but I don’t think this is the cause as the three way valve is stuck in the position where heads contents go straight to the sea cock.

Also, I have a no solids down the loo rule and that heads hadn’t been used for over a week anyway.
Maybe just old waste that hadnt been disposed of properly and was still lurking in the pipe? But a bit concerned about it finding it’s way back into the heads.

I appreciate this may not be enough information but if I could some receive some pointers as to what to check that would be appreciated?
 
You dont say what type of toilet but the general rule is that both inlet and outlet pipework should have loops with antisyphon valves if the rim of the toilet is not well above the waterline level on all angles of heel.

With Jabsco and similar the inlet loop must be between pump and bowl. Not between seacock and pump or you'll suck in air and little water

Lavacs are a different kettle of fish, with a pin hole air leak in the inlet loop and no antisyphon valve required in the outlet

Google may find installation and operating instructions for the toilet you have.

here are the two I mention

https://www.marlow-hunter.com/wp-content/export/Vendor-Manuals/Jabsco Manual Flush.pdf

TOPLICHT BLAKES LAVAC ZENITH MANUAL Pdf Download
 
Last edited:
thanks for the info.

it’s a jabsco manual head
i will take a look at how it’s plumbed. There is one anti syphon loop in there.
 
Tinto said:
thanks for the info.

it’s a jabsco manual head
i will take a look at how it’s plumbed. There is one anti syphon loop in there.
Click to expand...
Ive added a link to the manual

In theory a manual Jabsco with a twist a lock pump should not need the vented antisyphon loop in the outlet but I'm not so sure it is 100% effective
 
In order to avoid any unpleasantness and smells that you wish to avoid in the future may I suggest that when you evacuate the bowl you use a sufficient number of strokes to ensure that everything is discharged and nothing other than seawater remains in the big pipe. You do this by calculating the volume of the pipe between the bowl and the sea cock and dividing by the volume to the pump. That gives you the number of strokes, it's always a number bigger than you imagine, you should add a couple of extra strokes to be sure! There are numerous threads about this.
 
Fr J Hackett said:
In order to avoid any unpleasantness and smells that you wish to avoid in the future may I suggest that when you evacuate the bowl you use a sufficient number of strokes to ensure that everything is discharged and nothing other than seawater remains in the big pipe. You do this by calculating the volume of the pipe between the bowl and the sea cock and dividing by the volume to the pump. That gives you the number of strokes, It's always a number bigger than you imagine, you should add a couple of extra strokes to be sure! There are numerous threads about this.
Click to expand...
To save some difficult calculations, Jabsco recommend a minimum flush of seven full strokes of the pump per metre of outlet hose. More is better.
 
A Lavac vacumn head- wish to replace the big hose -toilet to pump. Will this be an unpleasant job to do ? Keep putting off
 
Surely simple answer is to CLOSE the seacocks after use ?

Reason for 'backflow' is probably water level in bowl is below boats waterline ?

My Blakes Royal has no anti-syphon but OUT pipe loops up to just above waterline ..... and my IN pipe has two valves .... seacock under the boards and a simple handi valve above the boards for daily use. Absolutely no need for anti-syphon if you use the valves.

My bog door has an instruction sheet pasted for 'user' to read while on the throne. It asks user to pump ay least 3 full bowlfull's after use. ... to ensure contents are 'gone'. I don't have holding tank.
 
Last edited:
vic008 said:
A Lavac vacumn head- wish to replace the big hose -toilet to pump. Will this be an unpleasant job to do ? Keep putting off
Click to expand...
Wasn't for me. The boat had been out of the water for a few weeks with seacock open so had to some extent dried out. I had also pumped a lot of water through the system before being lifted.
I would replace all the hose not just a section.
 
Refueler said:
Surely simple answer is to CLOSE the seacocks after use ?

Reason for 'backflow' is probably water level in bowl is below boats waterline ?

My Blakes Royal has no anti-syphon but OUT pipe loops up to just above waterline ..... and my IN pipe has two valves .... seacock under the boards and a simple handi valve above the boards for daily use. Absolutely no need for anti-syphon if you use the valves.

My bog door has an instruction sheet pasted for 'user' to read while on the throne. It asks user to pump ay least 3 full bowlfull's after use. ... to ensure contents are 'gone'. I don't have holding tank.
Click to expand...
Depends a lot on whether have a waste holding tank or not, and potentially on how it is plumbed. Our heads is plumbed to feed into the top of the holding tank. In this case closing the outlet seacock makes no difference to the OP’s issue. And indeed we sail with the outlet seacocks fully open when in open waters (UK tidal, not Baltic or Med etc).

But as others have said, likely the joker valve which is where I would start. Indeed just replaced ours for this reason before leaving the boat. Two screws and a 2 minute job - plus the 5 minutes careful preparation, and 15 minutes even more careful cleaning up (including in our case using the shower head to clean the entire heads compartment, even though only lost a few ml of water doing the job).
 
Thank you for your help everyone. I think the cause was previous owner not giving it enough flushes. It’s been fine ever since.

did some exploring and learned a lot. Sorry for the late update. Been up to my eyes on finding out what works and what doesn’t and then fixing it.

cheers!
 
You must log in or register to reply here.

Share this page

Top