Bored to Death: Shipworm Damage Devastates Docks

Hidden attackers lurking beneath the surface, secretly destroying your property without leaving a trace… While the premise may seem otherworldly, in reality marine wood borers such as shipworms and gribbles can destroy a wooden piling in under a month. Despite the high rate of destruction, the damage can often go undetected. According to the Louisiana State University Agricultural Center (LSU AgCenter),  “More than one-half of the volume of a pile may easily be destroyed without any evidence of injury being apparent on the pile’s surface.”

Unfortunately for docks in warm saltwater, the very means used to prevent rot and decay increase the shipworm-induced peril. “Wood can be maintained free of decay by submerging the wood in water and thus depleting the oxygen requirement for many wood-decaying organisms,” explains Todd F. Shupe of the LSU AgCenter. “This method prevents most insect injury but promotes injury by marine wood borers.”

A member of  the 500-million-year-old bivalve family, Teredo navalis (Latin for ship-eating worm) differs drastically from his happy cousin the clam. With a worm-like body measuring up to several feet long and a penchant for boring through wood submerged in saltwater, Teredo, commonly known as shipworms, have been destroying ships and pilings for centuries. According to Dr. Moori, curator of Zoology for the Manitoba Museum, the shipworm may even have caused Christopher Columbus and his crew to divert their fleet to Jamaica on his voyage to the new world.

What recourse exists in the face of such a formidable foe? Preventative measures yield mixed results. Costly metal sheathing surrounding each piling can prove ineffectual due to corrosion. Cement casings crack under the pressure and plastic and fiberglass coatings only cover up the problem. Pumping the piling full of poison can temporarily slow the infestation, but sufficient penetration is impossible with most hardwoods.

“Composite pilings eliminate the risk of marine borers such as shipworms,” explains Pearson Pilings president Mark Pearson. Composite fiberglass pilings like those made by Pearson Pilings are impervious to insect damage, marine borers, rot, rust and corrosion.