to fit or not to fit anti-syphon loops...

[Shearwater]

....in the loo inlet and outlet tubes ........ if you had just fitted an RM69 with sealock facility? I'd like to save the £35 especially by keeping the (soon to be new) stop cocks closed (when not in use of course). Sensible or a waste of money?

 

[nimbusgb]

Nearly 30 year old boat, no syphon breaks in the head inlets or outlets. Boat hasn't sunk ............. Yet.

You do have to check though. My heads the bowl is about 2mm below normal waterline level. I have seen someone leave the seacock open and the water get almost all the way to the top. Keep promising myself to jack them up by the thickness of a piece of ply.

 

[Phoenix of Hamble]

I wouldn't trust the sealock.... but closing the seacocks would prevent a problem..... OK until you forget though!

 

[VicS]

There is a warning in the instructions that says,

" Attention: The lock position doesn't give a 100% safety; for instance
hoses can break down. Therefore close all sea cocks during longer
absence and also during the night."​

The installation instructions also say,

" Any installation made below the waterline must have vented loop
positioned properly and all hose connections must be double-clamped.
Both intake and discharge seacoks should always be in a closed position
when the toilet is not in use."​

If you do fit vented loops the inlet one must replace the short hose between the pump and the bowl. If you fit it between the seacock and the pump you will simply suck in air when you try to flush the thing!

I know someone whose boat nearly sank during the night with the family on board due to one of the children not closing a seacock and there being no vented loops. Water was just up to the top of the bunks when he woke in the morning and realised something was wrong when the "cool box" floated past him! IIRC it was a RM69 but not the Sealock type.

 

[Rossynant]

+ 1 and better follow the above. Vents used to be mandatory in old safety rules, for a reason. It's small money for a peace of mind.
You know, Murphy Law, doesn't happen often but once is enough.
Had such problem, once.

Seacocks may fail, valves in toilet not trustworthy - and what a disgraceful way to go down...

(The first experiment already illustrates a truth of the theory, well confirmed by practice, what-ever can happen will happen if we make trials enough.
A. D. Morgan, 1866 "Supplement to the Budget of Paradoxes")

 

[SimonP85]

I have an unopened anti-syphon loop going spare if you want to save on fitting one:

http://www.ybw.com/forums/showthread.php?t=333128

 

[Otter]

I've seen pictures of the spaghetti loops with anti syphon breaks and occasionally they are OK when fitted in cupboards behind the loo but mostly they look a right old mess. Instead I fitted very simple ball valves in the pipe just before the loo, if you can remember to twist and lock a Jabsco you can remember to twist a pair of ball valve handles. No one's forgotten so far

 

[Sandyman]

.....................so far ?????

 

[Caer Urfa]

....in the loo inlet and outlet tubes ........ if you had just fitted an RM69 with sealock facility? I'd like to save the £35 especially by keeping the (soon to be new) stop cocks closed (when not in use of course). Sensible or a waste of money?

If you ever get 'flooded out' by someone forgetting to close the seacocks then you will regret the day you never fitted an anti syphon system especially if you do a lot of sailing.

It's not mega bucks to fit and a job easily done, make sure you fit it correct if your toilet is below water level.

Mike

Heads Before

Heads after

 

[Otter]

Wow that's one big Colvic Watson - side by side loos! We're slumming it with a single forward heads.

 

[laika]

Per VicS's post...can you trust that *everyone* on your boat will always close the seacock? If looking for some financial justification for vented loops: re-sale? If I was looking at a second hand boat and there was no vented loop on the outlet it would raise big red "bodger alert" flags which would make me wonder what else had been done without regard to normal standards of caution. Of course not everyone pays so much attention to plumbing...

As for loops on the inlet between pump and bowl...it's interesting to check out the plumbing on new boats at the boat show. Most AWBs with a manual twist-n-lock seem to lack a loop on the inlet. Most high-end boats are obviously electric, but if you look at manual toilets on nauticats and najads they are done "properly". All boat builders seem to put a loop on the outlet where the heads are below the waterline.

Does that mean the inlet loop is just arse-covering? After all, if the big mass producers don't bother it can't be all that much of a risk. When I replaced the vacuflushes on my boat with twist-n-locks I asked jabsco reps at a couple of boat shows this. Even verbally they wouldn't say that it was just a safeguard which could, with a little extra risk, be ignored where a twist-n-lock was fitted. They insisted that yes, it was required and not just "extra safety". I don't think they were just cynically flogging vented loops.

Despite it being obvious that the original manual (pre the vacuum heads which I inherited) installation on my westerly had had no vented loop on the inlet, I ended up drilling the extra holes (my loops are in a cupboard). Extra pipework does not add to the aesthetic appeal but it's as neat as it could be and I get to tut and maintain an air of superiority when looking at new Beneteaus I can't afford.

So. Based on the big manufacturers who want to minimise costs but avoid court cases: fit one on the outlet. The inlet might not be so critical with a locking pump. But the 19mm loops are cheaper than the 38mm ones (~£20?) so personally I went all the way and did it properly.

 

[jerrytug]

If you ever get 'flooded out' by someone forgetting to close the seacocks then you will regret the day you never fitted an anti syphon system especially if you do a lot of sailing.

It's not mega bucks to fit and a job easily done, make sure you fit it correct if your toilet is below water level.

Mike

Heads Before

Heads after

That`s nice installation mate,gentle bends,everything clear and not boxed in,check at a glance.

 

[dylanwinter]

loops

the slug was straight in and straight out

the short run meant that not much pumping needed

katie L has a couple of sweeping loups

loads of pumping needed to clear the system

and smellier if you do not do enough pumping

so I would rather not have them

mind you

my bog is well above the water line

D

 

[Pinnacle]

If you ever get 'flooded out' by someone forgetting to close the seacocks then you will regret the day you never fitted an anti syphon system especially if you do a lot of sailing.

It's not mega bucks to fit and a job easily done, make sure you fit it correct if your toilet is below water level.

Mike

Heads Before

Heads after

I'm curious. What does the black pipe that exits the hull above the inlet do/carry? Because it has a seacock, that suggests its below the waterline.

 

[Caer Urfa]

I'm curious. What does the black pipe that exits the hull above the inlet do/carry? Because it has a seacock, that suggests its below the waterline.

The black pipe is to an electric bilge pump below the main saloon sole boards, the reason it has a seacock is for 'back up' when sailing as the boat can be hard over on the port side or in heavy sea conditions so all outlets can be easily shut.

As I sail 95% of the time single handed and all year round or for 'whatever reason' the pipework can be isolated, as at sea you may not have the time or the conditions to start messing with a burst pipe or worse backflow of sea water coming aboard through an outlet (this obviously does not apply to deck drains).

Mike

 

[Rossynant]

Does that mean the inlet loop is just arse-covering? After all, if the big mass producers don't bother it can't be all that much of a risk. When I replaced the vacuflushes on my boat with twist-n-locks I asked jabsco reps at a couple of boat shows this. Even verbally they wouldn't say that it was just a safeguard which could, with a little extra risk, be ignored where a twist-n-lock was fitted. They insisted that yes, it was required and not just "extra safety". I don't think they were just cynically flogging vented loops. [...]personally I went all the way and did it properly.

Personally I had to deal with jabsco flooding the forepeak. There was no loop on inlet, just short pipe direct. So I closed the seacock to take the pump apart - but the seacock in closed position was still letting some water in...
You never know.

 

[Shearwater]

my thanks to all.....

....and I will take the advice to heart, Special tks to that font of knowledge VicS, a vent between the pump and the bowl I would not have thought of.

To Possynant, Murphy's Law I know well from my aviation loss adjusting days - if it can happen, it WILL happen and it will continue to happen until the regs are changed (etc) which is how our lives are now so safe.

OK, I'll do it. A pair of plastic Marelon valves and a pair of vents. Thanks guys, I think I would have done it anyway but it is really good to chat it over.

Simon P85 ...... tell me more of the 1.75 inch valve please; pm me - I check in most days.