What About Polyethylene Fuel Tank Repairs?

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Fixed tanks are generally safe from the sun, buried in the bowels of the ship. But jerry cans are often kept on deck, scorched by UV from the sun. They take a beating, hauled back and forth in the dinghy. Seams split and bottoms wear. Sunbrella covers can last for a decade at least, keeping the cans strong.

Gasoline cans pressurize and bulge. Specifically, the new ethanol formulations have greater vapor pressure than conventional gasoline, and left in the sun can reach unsafe pressures for tanks that have been weakened by the sun. Portable tanks should be stored out of the sun whenever possible. US Coast Guard regulations permit sealed cans below decks, though we don’t particularly like it.

Just for fun, we then tried repairing some cracks in badly sunburned jerry cans. The bottom line is that nothing worked, including welding, until we sanded through the sunburned material. Polyethylene just does not last forever in the sun. Think of it as an expiration date.

Polymer gasoline and diesel tanks cannot be repaired by any method. First, used tanks, and specifically used jerry cans, have generally been compromised in terms of material strength. Second, over the years, gasoline and fuel will have permeated the plastic to some extent. This internal oiliness makes it impossible to achieve a reliable and durable bond, even by plastic welding. This is true not only of polyethylene, but also of fiberglass fuel tanks, and as a result we do not recommend repair of any polymer tank.

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him by email at practicalsailor@belvoir.com.