The sea water in the toilet and outlet pipe can easily be removed as you correctly say by flushing through with fresh water before you leave. When you return the heads will indeed smell OK.
The problem that is harder to resolve is the sea water / decomposing biomass that remains in the inlet pipe. (the biology has already been well described) The first flushing will suddenly produce a pungent pong as this contaminated water comes into the bowl. The toilet system will then need several flushings to get rid of this water and bring fresh sea water into the system.
That's one of boating's smaller hazards though and if anyone is too sensitive to withstand the nasty niff; they are almost certianly too sensitive to go to sea anyway.
I've just come across this Topic, so please forgive this late posting. As a recently retired marine product manager with specific responsibility for manual and electric toilets over the last 25 years, I comment that:
1. The worst smell experienced - the so-called "rotten eggs" - does indeed come from the toilet inlet system, and NOT from the outlet, so nothing that you put in the bowl will prevent it. Some boats never seem to suffer from it - others are repeatedly plagued by it, whether on sea, river or lake. The relative positioning of the inlet and outlet seacocks may well be a contributory factor. ideally the inlet and outlet seacocks should be on opposite sides of the keel, with the inlet above, and ahead of, the outlet Other contributors have already correctly identified the smell as being hydrogen sulphide, the by-product of anaerobic bacteria, which are drawn in through the inlet seacock, and which have the opportunity to multiply during periods when the toilet is not in use - hence no, or negligible, smell whilst the toilet is being repeatedly used, but a strong smell when first used after periods of non-use. The only ways to be reasonably sure of eliminating it are either to introduce a bacteriocide into the inlet pipe immediately adjacent to the inlet seacock [as described by a previous contributor], or to convert the toilet to fresh water flush, BUT UNDER NO CIRCUMSTANCES SHOULD YOU EVER CONNECT YOUR MANUAL TOILET TO ANY PART OF YOUR HOT OR COLD DRINKING OR WASHING WATER SYSTEM ! [with or without loops or non-return valves !] However It is fine to connect it to a totally separate tank. [Electric toilets can be safely connected using the correct electrically operated valve designed for the specific purpose, but that's a topic in its own right]. 2. As the water drawn in from outside the boat is often inherently smelly, it is always a good idea to pump it all out and leave the bowl dry, or, if you want to leave water in the bowl [OK in calm waters but not a good idea at sea...], then by all means add fresh water to the bowl, using a bucket or your shower head. 3. If waste is left in the outlet pipework for prolonged periods, the resultant gases will ultimately permeate the walls of PVC hoses, which will then smell all the time, irrespective of what is inside them. Some so called sanitary grade PVC hoses are much better than others, but many published tests and the manufacturers' own small print suggest that no PVC hose is infallible. In America, the hose of choice is triple walled rubber exhaust hose, but you won't like the price, nor the difficulty in working with it. There is a simple, low cost solution [provided that you are not discharging into a limited capacity holding tank!] - always pump the toilet for long enough to discharge all the waste from the outlet pipework. Alternatively, just replace your discharge hose every couple of years, which will also solve the common problem of scale build up in the hose.
Thanks for your valuable input. The problem with your "simple low cost solution" - replacing the discharge pipe - is that getting at the pipe to replace it may not be as simple as all that. On our Sigma 33 it involved removing all the furniture from the heads compartment to get at it (when of course it was simply a matter of undoing two jubilee clips.)
The pipe was reduced to a fraction of its diameter by the build up of scale. However, by the time we had liberated it, it was late evening, the chandlery was shut, and we needed to rebuild the boat in time to go racing the following day. So we solved the problem by beating the pipe on the concrete hardstanding, so that the scale shattered and fell out!
It was obviously an extremely good quality pipe because it withstood the treatment, and went on to give many more years of service. It then took us several hours more to rebuild the boat. If we had paid the yard to do the work, the bill would have been considerable.
I think it would be very good advice to replace the outlet pipe say every five years to prevent the scale build up, but I understand that in some modern production boats you cannot get at it to replace it, because it is hidden, not by removable furniture like the Sigma, but by mouldings. So what happens when it blocks? (As it eventually surely will....) Do you throw the boat away?
Yes, the sea cocks were perfectly accessible and no problem. That has to be the case for Lloyds certification and now CE certification. Also the racing rules require you to attach wooden bungs adjacent to the seacocks so that you have something instantly to hand if the skin fitting fails.... So nothing to worry about there! It's not the skin fittings that are the problem but the tendency to hide "unsightly" pipework away behind glitzy bathroom fitments. It's part of the tendency to make yachts more like caravans and less like boats!
II can only recommend that you - and everyone else - adds de-scaling your toilet discharge hose to your annual maintenance [the inlet hose is not usually a problem - the scale is largely a by-product of your personal liquid waste!]. If your installation lets you work out a method of introducing and holding a descaling agent in the hose whilst it does its job - great! If you can remove the hose in the spring when the scale will have dried out, and the exterior wall is still odour free, your own method of banging it on hard surface is perfect! If not, try to gain access to as much of the hose as possible and bang it with a blunt instrument.
If this doesn't work for you, Cathy, and you do decide to throw your Sigma 33 away, just call me and I'll willingly take it away for you...
More seriously, I agree that for a whole variety of reasons, ranging from customers' cosmetic expectations to manufacturing cost considerations to simple failure to design for maintenance, very few boat builders take care to provide easy maintenance access to wearing equipment - including toilet hoses.
For the experienced skipper and crew only, I commend the pragmatic approach of several French sailboat builders. They simply ignore all the manufacturers' recommended safety advice about using ventilated anti-syphon loops. Instead they leave both the inlet and outlet pipework, and also the two seacocks, fully exposed to view. This results in easy access for maintenance, and fewer joints, so lower risk of leaks. If any leaks do occur, they are immediately visible. Stubbing toes on the seacocks reminds the crew that seacocks are there to be used! If they don't use them, and syphoning occurs, the seacocks are instantly accessible. The downside risk is that if the skipper is careless enough to leave the boat unattended with the seacocks open, it is theoretically possible that it may sink on its moorings! That said, in all my experience, I never heard of a boat sinking as a result of syphoning through toilet hoses [syphoning back through bilge pumps - yes, but through toilets - no].
Unsurprisingly, this approach does not meet with universal approval from new boat buyers, boat sales people or corporate legal staff!
All this anti-syphon stuff (even on engines) is all very well when the boat is new, but with a bit of salt & scale they always jam up and invariably are jammed in the "wrong" direction, so you blow your engine up through coolant starvation or cannot flush the loo. In nearly 40 years of owning off-shore boats, I've never ever had any anti-syphon devices, I've never had a syphon problem either. BTW I always loop all pipes that go to a skin fitting (except cockpit drains) up the the deck level, this will stop any syphoning and is completely fool-proof!
NB all pipes to skin fittings (above & below the waterline) should be double fastened with two jubilee clips at both ends!
Ah Chas, being a motor person you have failed to grasp that sailing yachts spend a lot of their time at angles which change the waterline fundamentally! What you think of as "above the waterline" can quite often, in practice, find itself below the waterline. And I have to agree with David about the belt and braces approach to jubilee clips. You can't always rely on crew members to turn off seacocks after using the facilities. And you don't want leakage in this department, above or below the waterline!
Is it in case one fails or to provide extra grip to the fitting or 2 'barriers' to leaks? Or because someone decided that was the requirement to meet some standard?
I sympathise with you over your recent struggles with the waste pipes. A few weeks ago on Cushla we had reached the point where some form of action was required to eliminate the awful smell eminating from the head/shower room. We flushed through the (virtually unused) holding tank thinking that whatever was causing it was located in there, but to no avail. So the next step was to remove the pipework.
I purchased new waste grade pipe for the inlet and discharge pipes and set to work. What i didn't readily appreciate was how stiff and unforgiving the old pipe had become. Being fitted out in South Africa (9 years ago), the pipe was what can be described as 'armoured' - and now full of scale, it was heavy and didn't want to flex. The inlet pipe was reasonably straight forward to remove - both ends being accessible, although i did have to route the new pipe back to the toilet using a new route. However the discharge was a nightmare! It was jammed at a point where it ran behind the 'one piece' shower room moulding and down under a bulkhead. It took about 4 hours of heaving one end and banging on the other end with a hammer to free it up! Eventually it came free sending the three us us pulling at it sprawling across the cabin, and of course spraying out any remaining foul water.
I must warn any other members who have to carry out this most unsavoury task to make sure that there is plenty of ventilation, and to take regular fresh air breaks. My head was stuck in the bilges for too long and i was overcome with a couple of serious dizzy spells. So much so that i thought we had put to sea because i couldn't stand up without steadying myself!
Fortunately, the moment the offending pipework was discarded ashore the whiff disapeared. On inspection of the pipe i found it to be seriously restricted with scale - probably to 50% of its capacity. The diverter valve was seized with the clag too. Feeding new pipe was easier because it had a slippery surface and was also 2mm smaller gauge - unfortunately this presented new problems - 38mm pipe onto 40mm elbows is hard work!!
It was 8 pm before all was finished. The smell had gone, hopefully for good. We also fitted the Puritec sanitiser as well which provides a much more appreciable odour and does actually provide a very pleasing 'blue' to the pan.
We live aboard so hopefully the bugs won't have time to multiply and create the problem again. However, if there are ways to avoid this in the first place then i highly commend members to take early action, whatever that may be. Jerry
Always found that a good assault on the pipe to be removed with a jig saw, to cut it into as many pieces as poss helps considerably. Why two jubilee clips? Well, you double up on the gripped surface so it is far less likely that any physical load or bending of the pipe will pull it off the fitting/device!
BTW I have noticed this season an increasing number of people drying their boats out, or being craned out, to have new skin fittings and/or seacocks, and last week, I saw for the first time a failed ball-valve seacock. A lot of these were on comparitively new boats too, (under 10 years old) so perhaps the standards of manufacture or materials used are diminishing? Either way I think a proper proper look at mine is due this winter, A complete strip amd inspection methinks, rather than waiting for the leaks and they struggling to fix between tides.
There's a massive difference in the quality of valves available from the cheap crap available in B&Q to some of the ones we use in the process industry which can cost thousands but won't fail.
I think we know which type production boat builders will use!
I understant the theory of double clips but it is really more important to ensure that there is no load on the pipe. Think back to tinkering with old cars; hoses usually failed right next to the clip where it was under stress.
For general purpose valves,fiitings etc. suggest anyone in need of these tries BES ltd.-a professional plumbers merchants-metric and imperial; various materials including stainless and old fashioned maleable iron(not suggesting this for boats)Also LPG gas fittings,pipes metric and imperial;oil and diesel fitting etc.-get their catalogue/order by phone /online-next day delivery uk wide from Birmingham.
Seacocks-still like the bronze taper cocks-unscrew the two nuts and plate across the top and you can dismantle them.
Luckily my toilet doesnt smell and all piping and seacocks easily accesible
On Hullabaloo, I still have the original (now 30 years old) seacocks.
They were designed and made by Landamores (Wroxham) who built the boat. Leslie Landamore who owned the yard was a very creative engineer and came up with all sorts of nice touches on his boats.
They are very diferrent to any others I have seen. The skin fitting & the seacock are integral, when closed there is a plate that makes the outside of the hull completely flush, this plate has a thick "O" ring and the outer edge of the skin fitting has a lip so the watertight seal is effected by the "O" ring being srewed down hard against the lip.
They are not attached to the hull in the conventional manner, having a metal flange about 8 inches diameter that is just glassed into the hull.
To open & close there is a handle that simply is pulled & pushed, the handle srews up tight in either the open or closed position. The great thing about them is there really isnt any maintenance to do except ensuring there is no growth inside them.
The strange thing about them is that they are made of an alloy that looks like aluminium but clearly is a bit more special. I took one out of the hull (it was redundant) a couple of years ago and it had no corrosion or electrolysis at all, I had to saw right through the fitting and it was all nice clean solid metal.
