Which Oil-Spill Products Work Best

We all know water and oil don't mix. But when boats are involved, it can be a challenge to keep the two apart. Oil, gasoline, diesel, and other hydrocarbon-based lubricants power almost all of our boats at least some of the time, and they aren't going away anytime soon. Federal law is clear when it comes to oil and water: It's illegal to discharge oil (including gasoline and diesel) into United States waters, and doing so can result in hefty fines. Any discharge causing a sheen or discoloration on the water's surface must be reported to the U.S. Coast Guard National Response Center. It only takes a drop or two to create a sheen, which can easily occur through an unintentional overflow when fueling, or the accidental discharge of oily bilge water.

The law is clear about spills in the water, but less clear on what you can do once one has happened. A variety of products claim to remove or render harmless spills of oil, gas, or diesel, but do these deliver on their promises? And is it legal to use them? Our BoatUS Foundation for Clean Water & Boating Safety took a close look at 21 spill-response products. We found that, despite their marketing claims, many of the products were ineffective, highly toxic, and were not legal for the average boater to use. But three of the products performed well in all of our testing, and offer boaters options for quick reaction when oil and water come together.

The Complex World Of Spill Response

By law, if oil gets into your bilge, it's illegal to add dispersants or emulsifiers, and then discharge it overboard. If oil gets into the water, the only products nonprofessionals can use to remove it are "contained simple sorbents" — pads, booms, and other natural or synthetic materials that soak up hydrocarbons and can be completely removed from the water afterwards. But not all simple sorbents are the same. Most conventional inexpensive polypropylene absorbents, like socks, diapers, and paper towels, don't meet the so-called "one-drop rule:" If even "one drop" of oil is released, the sorbent is considered saturated, and local laws in many places require it be disposed of as hazardous waste. More advanced products are designed to encapsulate or solidify the hydrocarbons; after they've been used, these products can be disposed of as normal garbage in many jurisdictions.

As if all that weren't complicated enough, many of the products being marketed to boaters for spill cleanup are really not appropriate for dealing with small spills or enclosed spaces. For example, bioremediation products, those that rely on microbes to break down the oil, take days, weeks, or even months to do their work, so they wouldn't work fast enough for boaters dealing with a fuel-vent overflow or oil in the bilge.

Even worse, only professionals can legally use many products on open water. Once a product is listed on the Environmental Protection Agency's "National Contingency Plan Subpart J Product Schedule" — the official product list professional spill responders must use — it becomes illegal for use by the average boater. Professionals are allowed to use a much broader range of products on a spill, in part because they have additional training to analyze the incident and its complicating factors.

Cut through all the red tape, and you need to know two things. First, contained simple-sorbent products are not included on the EPA's list and are therefore available for use by average boaters to clean up a spill in the bilge or in open water. Second, many products that come as loose granules or as liquids are not legal to use in open water because they cannot be completely recovered; but some may still be useful for cleaning up spills in the bilge. So which products work best?

How The BoatUS Tests Worked

Barnacle larvae.

To ensure that our tests were done to high and independent standards, we sent one set of products to the Duke University Marine Lab in Beaufort, North Carolina, for chemical analysis to determine the products' effectiveness and toxicity before and after exposure to petroleum. We kept another set for our own staff to evaluate, to determine if they performed as promised and removed oil from the water.

Duke tested the toxicity of the products using seawater and 10W-30 motor oil. Some of the bioremediation products noted that 90 days were needed to see full results, so Duke set each product up in a "micro-bilge" and left it for four months, which they determined would allow all the products ample time to work. After four months, Duke added barnacle larvae to samples from each micro-bilge and left it for 24 hours, then analyzed the number of living and dead larvae to determine toxicity. They also conducted a visual inspection of each micro-bilge under LED light to determine the amount of visible oil remaining. These longer-duration Duke Marine Lab tests were intended to simulate what might happen when a product is used in your recreational boat bilge, where a small amount of oil could remain for some time, giving the product time to do its job.

Top-Performing Oil Absorbers And Their Uses

Meanwhile, BoatUS Foundation staff evaluated the products in short-term tests. We used plastic bins large enough to hold the largest bilge socks, Chesapeake Bay saltwater, and diesel fuel, filled the bins to a predetermined level with bay water, and added the diesel and product, one at a time. Each bin was agitated and observed every 15 minutes over one hour. Then the product was removed, we recorded visual observations, and tested the remaining water with petroleum-detection strips. The Foundation's practical experiments were intended to simulate an open-water spill — say, at a fuel dock, or in an accident — when you'd need to act very quickly, be required by law to remove the product once it had finished its job, and when waiting 90 days for a product to fully work wouldn't be feasible.

The Take-Away

Of the 21 products tested, only three were rated in the top-performance category (no visible oil after four months and low in toxicity) by the independent Duke Marine Lab and determined to be legal for use by recreational boaters. The same three performed best in the Foundation's practical one-hour tests. A disappointing number of products ended up on the opposite end of the spectrum with extremely high toxicity and highly visible oil remaining after four months. The table above highlights the top performers from both tests.

Duke found mixed results when testing loose products (powders and liquids); plus, the use of loose products on open-water spills is usually only for professional use as they must be contained and completely removed from the water after use, as is required by law. While the top-performing Enviro-Bond 403 granules and C.I.Agent granules were easy to remove from the water, many other loose products appeared to dissolve in the water or were nearly impossible for nonprofessionals to remove without a skimmer, helping us to better understand the resrictions on the use of many of these products. The liquid products were also impossible to remove from the water during our field evaluations, making them better suited to cleaning hard surfaces ashore. We found loose products could pose a challenge in windy conditions, where they would be difficult to contain and could blow to areas not impacted by the spill.

Several companies touted bioremediation products that either contain natural microbes or attract naturally occurring microbes to break down hydrocarbons. While these products promise to convert oil into a nonhazardous substance for easy disposal, they take much longer to break down the oil, according to the manufacturers, and won't work in cold temperatures. Duke found that these bioremediation products didn't perform as effectively as promised — many still had visible oil remaining after four months and had very high toxicity.

What Does It Mean For You?

Overall, we found "contained" products, like socks, pads, and pillows, to be the practical answer for most boating needs. They can be placed in the bilge or under your engine, and can last for months, soaking and holding small drops. Most contained products can also be used on open-water spills to minimize damage while awaiting professional response after reporting the spill. Booms, pads, and socks can be removed easily from the water after they do their job, and if they're encapsulated they can be disposed of as normal waste in many jurisdictions. Make sure any absorbent product you leave in your bilge is secured where it can't interfere with bilge pumps or engine operation, especially if the product were to float in bilge water. Check them regularly to make sure they remain in place and haven't become saturated. Legal disposal methods for oil-soaked absorbents vary county by county, so check how to dispose of these products in your area.

Remember, it's illegal to add dispersants (soaps) to your bilge for the purpose of masking an oil discharge; be sure either to do this work ashore and collect the discharge in a bucket, or use a sponge or handheld bilge pump to ensure nothing is pumped overboard. Finally, spills pose serious health and environmental risks. Always remember safety first, and never try to contain gasoline spills.