Scent to try us

Practical: heads

Tom Miller offers some practical tips on how to remain in good odour with your friends when going a la toilette.

Nothing focuses the attention of the sensitive crew member on board a small boat like a pressing need to visit the heads. Planning on how to manage the next encounter with the beastly device behind the curtain often promotes an all-encompassing anxiety that can dominate the weekend cruise.

The importance of a user-friendly heads was brought home to me a few years ago when there was an urgent need for a boating partner to help finance a yacht purchase that threatened to over-extend the family budget. A prospective partner and his lady came out for a weekend sail and after a pleasant evening at anchor and a glass or two of wine the cheque was as good as in the bank.

The situation took a turn for the worse next day when early-morning ablutions blocked the toilet. I assured the guests that the problem would be addressed and remedied after breakfast. However, mid-breakfast the need for an urgent visit to the toilet by one of the party became apparent. The best that could be offered was a bucket which - at short notice - served its purpose admirably. However, I could feel the cheque sliding away as the bucket and its steaming hot contents were eased past the breakfast table while the diners concentrated their attention on the tea and toast. Predictably, the proposed partnership was declined.

Odour control
Recreational boaters will have their own priorities when it comes to listing problem areas in the heads. Top of my list is odour control and more than a few brain cells have been burnt out during the hours of concentrated thought that have gone into resolving this issue. The "breakthrough", as they say, came last summer when a news item on the radio reported the case of a Swedish woman who was suing an airline for $1 million over an incident on one of their planes. It turned out that the woman used the toilet during a flight from Sweden to the US but made the mistake of pressing the "flush" button while sitting on the throne. Apparently she was fairly generous aft and was sucked onto the seat. For some reason she pressed the button a second time and her fate was sealed, so to speak. She was freed several hours later when the plane landed and engineers were able to release the vacuum.

Brainwave
While idly musing on the woman's predicament, the realisation came that her unfortunate experience provided an important lead into effective toilet odour management. In effect she had sealed the bowl and, once the contents had been flushed away, the system would have been odour-free. The general principle should also be applicable to the marine toilet.

This line of thinking led to the development of the perform-and-pump concept. The procedure involves opening the seacock and flooding the bowl in the conventional way. However, the secret lies with the user opening the inlet valve on the pump and flushing solids from the bowl into the holding tank while remaining seated. Matching the water inflow to pumping output requires judgment but can readily be mastered with a little practice. Foam strips glued to the underside of the seat between the rubber cushions also help to complete the seal. The result is an odourless heads operation that achieved a high approval rating over a six-month evaluation period.

That idle smell
The other underwhelming phenomenon associated with most heads is the pungent, sulphurous, nose-tingling odour that fills the boat when the toilet is flushed after lying idle for anything from a few days onwards. The explanation for this sensory insult lies within the plumbing system, where anaerobic micro-organisms form a biofilm that coats the lining of the hose connecting the seacock to the toilet.

Micro-organisms from the biofilm reproduce in the salt water, producing a concentrated microbial culture whose byproducts include the mercaptopurines. These extremely smelly compounds are responsible for the stench experienced when the seacock is opened and the contents of the plumbing are delivered into the bowl. The usual response is to attempt to mask the smell by the liberal use of air fresheners, which has little chance of success and ends up producing a lavender-modified mercaptopurine that smells worse than the unadulterated material. Characteristically the smell disappears when the toilet is in regular use during the cruise, only to reappear once the system is closed down and the permanent biofilm re-contaminates the hose contents.

Prevention
The solution to the problem lies in taking steps to prevent the sulphurous by-products forming in the first place. In practice this involves limiting the ability of the biofilm to re-contaminate the salt water in the hoses and the terminal section of the outlet Before leaving the boat for any length of time the reservoir is filled with a microbial growth-inhibiting preparation, the inline stopcock opened and the contents of the reservoir sucked through the system into the bowl using the toilet pump. A second 1500ml flush is pumped through in the same way and the contents of the bowl then emptied into the exit side of the plumbing. The outcome is a system filled with a biocide from the inlet through to the outlet seacock.

Biocides
Obvious candidates are the chemically based materials with varying active agents and modes of action designed to sanitize and manage holding tanks. The majority of these are formulated to break down solids and do not provide an answer to biofilm control, although they can often be effective in the short term. More appropriate are products that contain a microbial biocide capable of the long-term suppression of bacterial growth. Avoid using bleaches and sanitisers that contain petroleum products or alcohol because these may attack seals, valves and gaskets in the pump. Boats that have a hand basin in the heads already have a reservoir in place and a simple plumbing alteration or two may be all that is required to install an effective flushing system.

An alternative, or perhaps complementary, approach would be to install an Airolux unit designed specifically for marine applications. The device consists of a 12-volt extraction system, secured below the toilet seat, which directs air from the bowl to an odour-absorbing filter. It is compact, unobtrusive and said to provide "ultimate ventilation" (0800 726 326).

Exit side
The use of non-sanitation-grade plumbing material and a failure to flush away solids adequately can result in the products of decomposing residues permeating the hose and diffusing into the surrounds.

Contamination can be detected by wrapping a rag soaked in hot water around the hose close to the seacock. A sniff of the rag after it has cooled will tell the story and may indicate a need for hose replacement.

Ventilation
Adequate ventilation may also make a significant contribution to the situation. Most heads are equipped with either a dorade or mushroom ventilator: a computer cooling fan conveniently running on 12 volts and sited under the ventilator provides a cheap and effective extraction system. Another option is to replace the ventilator with a solar-powered extraction unit installed on the deck.

The outcome of the changes will be a boat that smells fresh and inviting at all times. The next challenge is to reduce the sound effects associated with action in the heads . . . Any suggestions?

AUTHORS BIO.

Dr Tom Miller is an enthusiastic cruising sailor who has covered 25,000nm in his current boat, Fantasy, a 10m strop-planked kauri sloop. He is based in Auckland and enjoys the spectacular sailing opportunities offered by the northeast coast of New Zealand. A Whitsunday Island cruise is a high priority.