LM 27 New toilet

[bobevans]

As part of the refit of my new-to-me LM27 I am replacing the toilet. It appears that the original installation had no vented loops in the pipe work as is recommended for the Jabsco toilet which I intend to install. I estimate that the toilet is around 0.75 metres below the waterline so, in theory at least, needs vented loops to both the inlet and outlet pipes. However, given that the boat has the tuck-away sink, such loops are difficult to install without making it impossible to push the sink back against the hull side. 

What have others done?

Bob

[Sula]

My LM27 also had no vented loops in the toilet hoses, presumably as original.

It is therefore dependent on the valves and their seals in the toilet pump to prevent the toilet filling (and overfilling) by syphon action. (Unless you close both the inlet and outlet seacocks every time after using the toilet, which is unlikely to happen in the LM because the seacocks are not readily accessible.)

This arrangement was quite common on older boats, but is now general considered poor or unacceptable practice - there is a risk of sinking the boat (or at least causing a lot of mess and salt-water damage). While I suspect there are many owners continuing to live with this arrangement, I very much doubt that any surveyor would approve it, and I suspect one could risk an insurance claim being refused if a boat was sunk through the lack of vented loop provision.

I have had a previous boat with no vented loop and never had a problem at all with it, but the toilet on my LM27 has twice filled by syphon. The waterline is (at least in my boat) almost exactly the same height as the rim of the toilet. So when it fills by syphon a small trickle of water has overflowed the toilet, then the 'tray' in the heads compartment floor, then soaked a patch of the saloon carpet before collecting in the shallow rectangular indentation under the cabin sole at the aft end of the saloon. (Both times I had only discovered it as I was walking barefoot in the saloon and felt the wet carpet.) It is lucky that on both occasions the boat was moored in a very sheltered marina. Had it been on a mooring, or underway, and subject to heeling, it could have been a lot more serious.

The toilet in my LM27 is an ancient TMC. I had replaced the valve seals with a service kit, but this did not prevent this spillage happening again.

I am replacing the toilet and have faced the same problem as you. I have yet to determine the way forward, but the following ideas have occurred to me.
a) Cut notches at the rear of the the sliding sink to accommodate the pipes, carry them on upward and fit the inverse U vent fittings in the rear of the locker compartment above the sink. (Note that my current sliding sink is not the original LM one, though I hope to get one, so don't know how feasible/challenging this would be to do.)
b) Fit seacocks inside the heads compartment for both inlet and outlet, so they can be easily closed and open (but one must still remember to do so!). These seacocks would be in addition to the ones on the through-hull fittings.
c) Rely on the valve seals of the toilet pump(s), with no vented loops, but fit a water-sensor (connected to a remote alarm) in the heads compartment floor.
d) I have yet to check the relevant heights on board, but under whether it may be possible to run the pipes through the aftward bulkhead of the heads compartment and have the vented loops as high as possible under the sink. Apart from any other considerations, the larger diameter of the outlet hose makes it bulky and prevents tight bends for such an arrangement.
e) Electrically operated seacocks (or supplementary valves) in conjunction with an electrically operated toilet, arranged via relays such that the seacocks/supplementary valves are only opened while the electric toilet pump is being operated, and automatically close immediately afterwards.  (This is not an option for me, on grounds of cost.) 

Do let me know if you have any other ideas!


You may well know the following, but just in case -

There is nothing specific about the Jabsco that requires the vented loops, it applies to all conventional sea toilets (with slightly different venting arrangement for the Lavac, because it operates differently). The current Jabsco specifically has a twist-lock on the pump to secure it closed, so should be less liable to leakage and hence syphoning than toilets without such an arrangement, but it is not completely reliable.

Note that vented loops need (ought?) to be above the heeled waterline.  This is significantly higher in the boat at its sides than the waterline when the boat is level.  The heeled waterline is lower the closer you get to the boat's fore and aft centreline, but of course most other considerations make this difficult to locate the loops near the centreline on the LM27 (and most other boats).

[bobevans]

Thank you Sula. I agree with the options that you have outlined - I certainly have considered both a) and b) as potential solutions but I feel that c) is too risky while d) and e) are too complicated. I have been thinking that the secondary seacocks idea, your b), is the most practical. I'm replacing all my seacocks with the TruDesign plastic valves and fittings and I'm going to measure the heads compartment to see if two of these valves could be practical in terms of installation and accessibility. I'll let you know how I get on! Bob