Bilge Cleaning And Maintenance Guide
Proper bilge maintenance with biodegradable cleaners and regular inspections ensures better boat performance and environmental responsibility.
May 23, 2024
Step onto a boat that has damp bilges and you can smell it, especially if the vessel has been closed for a few days. At the best of times its the prickling odour of musty library books laced a vague damp forest smell that hangs in the air. At the worse is the suffocating stench of spent fuel and rancid oil, mixed with the decaying funk of salt water and stinky shower drains. Any way you smell it, it isn’t pleasant.
Above: A woman scrubs and cleans the bilge onboard a sailboat. Image created with OpenAI's DALL-E.
The bilge is space below the floorboards where hoses, wires, pumps, and float switches reside, often forgotten about until there is a problem. Damp, dark, full of hard to reach corners the bilges is never a fun place to work, so it’s not surprising that too many boaters ignore the bilge until it demands attention. However, keeping your bilge clean and dry isn’t difficult and doesn’t require any fancy equipment.
Preparation
Before you reach for a bottle of cleaner or grab a scrub brush, it is important to note that there are strict laws, and heavy penalties, when it comes to discharging waste water.
In the USA, the Federal Water Pollution Control Act of 1948 was formally amended in 1972 as the Clean Water Act with the purpose to regulate discharges of pollutants and to implement pollution control programs. Under the Clean Water Act it is “unlawful to discharge any pollutant from a point of source into navigable waters...” That includes storm drains, ditches, and sewers. If caught dumping your dirty bilge water, a five-figure penalty can be applied on the spot.
This means that if your bilge is oily, or fouled with anything that could be considered a pollutant, all discharge must be disposed of at a proper waste water management facility. Check with your marina office or local marine authority for the location nearest you.
Cleaning the Bilge 101
Cleaning the bilge isn’t rocket science, but there are a few things you can do to make it easier.
Use a biodegradable bilge cleaner. Bilge cleaners are specifically formulated to be tough on dirty but easy on materials on your boat like fibreglass, stainless steel, plastics and paints.
These cleansers are typically a citrus- based degreaser or have emulsifying properties that will breakdown and suspend particles of oil and grease. Many act as both a cleaner and deodorizer, and several work with both fresh and salt water. Make sure to select a biodegradable cleaner.
Some cleaners claim to be scrub-free, using the motion of the boat to agitate the product and do all the work. But let’s face it, if you want to properly clean the bilge you are going to have to get your hands dirty. Since bilge maintenance should be part of your boat care routine, and most products have a long shelf life, it makes sense to buy in bulk.
Avoid Harsh Chemicals
Always avoid using harsh chemicals, abrasives, and acid-based products as they are both not environmentally sensitive but can cause damage to finishes, hose clamps, wiring and bilge pumps. Not to mention these types of cleaners hard on your hands. Never use bleach in the bilge!
Turn off bilge pumps. Easy way to mistakenly pump dirty bilge water overboard is to trigger an active bilge switch. Turning your bilge pumps off at the electrical panel is a sure way to avoid costly mistakes.
Wipe up dirt and oil first. Getting rid of dirt and oil residue before adding cleaner will save it from being spread around.
If the bilge is dry use a damp rag or heavy duty disposable shop cloth. If the oil is floating on dirty bilge water try using an oil absorbent sheet. These are specially designed to pick up oil and gasoline but repel water. Each sheet will absorb up to 25 times its own weight, which means a little goes a long way. They can be found in most marine and automotive stores and are handy to keep on board in case of accidental fuel or oil leaks.
Clear limber holes of debris. These small holes, usually found in the boat’s stringers, allow water to drain to the lowest point in the bilge. Easily fouled, it pays to check them before you start cleaning.
Elbow grease and patience go a long way. Most stubborn stains and smells can be removed with a good soak and some vigorous scrubbing. Letting the bilge soak in cleaner for an hour or two will help breakdown dirt, grime and odours. After that, a stiff brush and a good scrubbing are usually all that is needed.
Preventative Maintenance
Now that your bilge is clean, dry, and smelling fresh it’s important to keep it that way. The best way to keep the bilges dry is with regular checks and preventative maintenance. Let's take a look at some of the key steps in preventative maintenance for bilges.
Regularly check the prop shaft and rudder post for leaks. It is important to do this both while stationary and when underway. The rotation of the shaft and forces on the rudder while in use may result in leaks that are not apparent while the vessel is on the dock. Like a leaky tap, a small but regular drip can result in significant water in the bilge.
Check hose clamps and fittings for rust and replace when necessary. This includes pressurized water systems, fuel and oil lines, and holding tank fittings.
Check salt water systems. Inboard diesel engines and generators, some refrigeration units, and RO watermakers all draw salt water. Regularly service raw water pumps to avoid wear and subsequent salt water ingress. Check wiring and connections on raw water pumps. Inspect sea strainer, hoses, hose clamps and fittings, and skin fittings that might cause a salt water leak.
Keep bilge pumps and switches free of debris. Having properly functioning bilge pumps is important. Check the wiring and connections for abrasion and corrosion. Float switches are notorious for getting fouled, so inspect for any small debris or sticky build up that may cause malfunction. If possible, check the pump impellers.
Monitor fridges and aircon systems. Condensation is part of cooling systems. Regularly emptying drip trays and cleaning condenser plates will not only make your equipment more efficient it will eliminate stagnant water overflowing into the bilge.
Check engine compartment for oil and fuel leaks. Simply placing an oil absorbent pad under the oil pan will catch any drips and allow you to easily monitor for leaks.
Avoid routing the shower, deck drains, and anchor locker into the bilge. It may seem easy to divert all waste water into the bilge but it is guaranteed to keep your bilges damp and smelly. Installing a small enclosed shower sump is an easy way to keep hair and soap scum contained and having a separate drain in you anchor locker will avoid the funky saltwater stink.
A Happy Bilge is a Dry Bilge!
Good boat maintenance includes proper bilge maintenance. Using purpose-designed biodegradable bilge cleaners will ensure that you have minimal environmental impact, and taking time to preform regular checks to the systems below the floorboard will mean less time scrubbing dirty bilges. Investing a little preventative maintenance time to the bilges means more time on deck having fun.
