Keeping the interior of a yacht smelling sweet is always a concern to the stews. The reality of smell issues is that it really is the responsibility of the engineer.

Keeping the showers, heads, sinks and drains smelling good is easy if one is using an eco-friendly product that works, such as those with enzymes.

A chemical that has no place on a yacht is common bleach. Bleach not only destroys the seals in shipboard heads, it also kills the much needed "good bacteria" in the gray- and black-water tanks. This "good bacteria" is required to help keep odor control in-check.

Odors in garbage and waste collection areas, heads and galleys arise from the degradation of organic waste, causing an increasing bad smell of amine, ammonia and mercaptan gases. Traditional cleaning chemicals usually involve toxic chemicals such as caustic acids, chlorine and disinfectants that are harmful to the environment. Bio-enzymatic cleaners are an effective and environmentally safe alternative. These enzyme factories replace bleach, acids and caustics.

The U.S. Navy invested millions of dollars to discover a solution for their warships' odor problems below decks. Chemists at a company called Unitor developed a totally organic way to control environmental odors. The product line is known as Gamazyme.

Gamazyme cleaners contain active bacteria cultures that digest organic fat and grease (as a means of gaining carbon for food), and converting them into water and carbon dioxide. Gamazyme products are specifically designed for safe and effective treatment of drain lines, grease traps, gray- and black-water tanks.

Gamazyme, which is approved by the U.S. Department of Agriculture and the U.S. Naval Medical Command, comes in several products, each designed for a particular shipboard task.

Gamazyme 700FN. (By the way, the FN stands for "For Navy.") 700FN is a super-concentrated powder with eight specialized bacteria strains to boost the biological activity in holding tanks. It breaks down all components of sewage starch, protein, cellulose, animal and vegetable fats, oils, grease, hydrocarbons, detergents and sulphides in addition to breaking down the paper found in black water tanks. It comes in 12Kg tubs.

I mix two cups of 700FN in a five-gallon bucket of hot water, stirring every 15 minutes for an hour, to introduce oxygen into the enzymes. The bacteria in Gamazyme are aerobic, meaning they need oxygen to live. They literally come alive with the process of stirring oxygen into the brew.

After an hour, I pour a cup of this enzyme brew into each sink, shower drain and head.

If you follow this methodology every three weeks, your vessel will smell great and you will avoid water flow backs due to clogged drains.

Gamazyme BTC. This is the only product I use onboard to clean my heads, sinks and showers. BTC stands for Biological Toilet Cleaner. This will absolutely keep your drains free running and leave a pleasant fragrance throughout the yacht.

Normal toilet cleaners often use hazardous chemicals that cause disinfection and foaming. Because they kill all known germs, they also kill the natural-occurring good bacteria in the sewage system and they produce foam, which is a death to vacuum-style heads. The low-foam surfactants and antifoams in Gamazyme BTC ensure that the product does not contribute to foaming problems. I keep the one-liter containers in each head for daily use.

Gamazyme DPC. The drain and pipe cleaner comes in a water-soluble sachet that contains a blend of bacterial strains and enzymes. As with 700FN, DPC keeps sinks, drains, pipes, black- and gray-water tanks free of fats, grease, starch and other organic waste. Regular use eliminates obnoxious odors from escaping from shower and sink drains.

Gamazyme Digester is a life-saver for an engineer who needs to keep the dirty water flowing and cannot afford a breakdown with owners or charter guests aboard. This patented liquid product contains a synergetic blend of highly specialized bacteria and enzymes that increase organic degradation and eats through organic waste products.

I have been able to free the last dozen or so stuck float switches in my black- and gray-water tanks with Gamazyme Digester. This liquid is delivered in a 20-liter bag in a box packaging.

Gamazyme Toilet Descaler is typically used in the cleaning and descaling of vacuum toilets and lines fouled with water scale and organics on board ships.

The product is used as part of a preventative maintenance concept, however it will also cure existing deposits in pipes.

Toilet systems tend to experience scale formation at the toilet level and the pipeline level in vacuum conditions. Because systems under vacuum are dry 99 percent of the time, the water evaporates and a scale can form. Not treating the problem leads directly to expensive dismantling of the system every two or so years. This can be avoided by regularly adding Gamazyme Toilet Descaler in water-soluble sachets named Solupacs.

Gamazyme BOE is a biological odor eliminator that contains bacteria, enzymes and a neutralizer that eliminates foul odors on contact. This is excellent for use in garbage cans.

For years, I have been purchasing my Gamazyme products direct from Kevin Kelly of Unitor in Texas. Recently, Unitor was purchased by Wilhelmsen Corp., which has taken Gamazyme global. The largest purchaser of the product is the world cruise ship industry.

Yacht crew can still purchase direct from Kevin. His phone number is 1-281-867-2042 and his e-mail is: kevin.kelly@wilhelmsen.com . Additionally, National Marine Suppliers in Ft. Lauderdale can arrange for your purchase of Gamazyme.

Contact Capt. David Hare at david@hare.com.