Welds on Your Boat Require Special Care

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The irregular shape of welds makes them difficult to inspect using ultrasound technology. Visual inspections can also be deceiving-especially with new welds. The prettiest bead can have internal voids and poor fusion. After a while, that pretty bead will begin to bloom with corrosion and cracks.

Critical welding, be it oil tanks, high pressure steam, or commercial shipping, all have minimum inspections standards, but the recreational marine repair industry does not. A full-blown X-ray inspection is overkill for minor hole repairs, but the welder needs to follow some basic steps to achieve the best results. The task is complicated if the alloy is unknown.

For new fabrication, the welder should prepare a test sample, joining two 2- to 4-inch strips of the metal to be used together, welded in the orientation in which the welder will be working (if it is overhead, they must be welded overhead).

When finished, chip the slag away and inspect closely for cracks. Cut the sample into strips about 1-inch wide, crossing the weld at 90 degrees. Clamp the test strips in a vise and bend them backward against the weld. A properly welded 90-degree angle should double over without cracking the weld.

Welds can also be checked for cracks and voids using a penetrating die. After welding, chip away all slag, grind smooth, and inspect as directed using a penetrating dye.

For welded tanks, diesel fuel has an uncanny way of finding pinholes. You can paint the inside of the weld with diesel fuel, wait 24 hours, and inspect for any evidence of seepage.

For more on non-destructive testing, see “DIY Materials Testing” from this issue.

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.

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