DON CASEY REPLIES
If you want a clean bilge, you have to scrub it. There is no pour-in solution. If an application of soapy water would work, sinks and bathtubs would stay clean. As a rule, the first step in cleaning a bilge is to drop in an oil-absorbent pad or pouch to try to separate and remove as much oil as possible. In your case, if you have already used detergents, and if there was oil in the bilge, it is emulsified and the pads will no longer work. The second consideration is the location of your boat during the cleaning. If it is in the water, you may need to catch your bilge pump discharge to be legal and/ or responsible. (Speaking of which, during any soaking stages, be sure to disable the bilge pump.) Given that your stated objective is to disinfect, I would start by pouring in a gallon or two of white vinegar, then add water as needed to flood the entire area you are trying to clean. Chlorine can be more effective, but it is also more dangerous to your health, harder on your boat and more damaging to the environment. Stick with vinegar, and give it a few hours to maximize the effect before pumping the bilge dry. After that’s done, come back with a strong solution of laundry detergent (Wisk is good) and hot water. Cable tie and tape a suitable brush to a length of dowel, and do the best you can to brush the entire surface area of your bilge. This will dislodge deposits and hopefully put them in suspension in the detergent solution. After that, pump—rinse—pump—rinse—dry. Another effective alternative is to use a pressure-wash wand. However, in my experience this approach can also be distressingly messy if the bilge is really dirty. In either case, the only lasting solution to bilge odor is to get the bilge free of everything except water.