Top: Out-of-position welding of aluminum poses no problem for Mission Marine. Inset: Mission Marine produces a GTAW-like bead appearance with GMAW equipment.

Mission Marine Ltd. (www.missionmarine.com) is a five-yearold fabricator of customized, all-welded aluminum catamarans. Bill Waldock, company president, has worked with naval architects and marine engineers to design two-hull boats that are light, strong and seaworthy in the toughest of conditions. Producing reliable, all-welded, aluminum boats requires strong welds with minimum heat distortion. Welders at Mission do that with equipment and consumables that facilitate and improve on their technique.

"We make vessels that go out at night with winds at 50 or 60 mph," says Waldock. "Our customers are betting their lives on our welders." Those customers include government agencies, police departments, coast guards, firemen and homeland security.

Aluminum sheet metal that is 3/16-in. to 3/8-in. thick is used for the frames, while 3/16-in. to 1/4-in. thick aluminum sheet is used for the skin. Welders commonly lay down a bead in hard-to-reach areas and perform out-of-position welding.

Mission Marine uses Lincoln Electric Co.'s (www.lincolnelectric.com) Power Wave 455M/Power Feed 10M semiautomatic welding system for thicker materials, Power MIG 300 push-pull wirefeeder/welder system (recently replaced by the Power MIG 350MP), SuperGlaze 5183 aluminum MIG welding wire, and 100 percent argon shielding gas. These machines and technology allow Mission's welders to adapt more precisely to varying weld parameters and applications. Lincoln Electric says the added control produces more consistent quality and more forgiving arc characteristics.

Mo Madyun, a Mission welder, says the added control helps minimize distortion. "The Lincoln welders are smooth, and we can change modes without thinking about it," he says, adding, "I prefer this technology for its controllability." He also likes Power MIG's ease of use, saying he could have a novice operating the machine in 15 minutes.

In addition, he says Power MIG delivers improved arc heat control for welding thinner materials. The unit provides good penetration and better surface oxide cleaning than standard MIG or pulsed MIG, as well as a TIG-like bead appearance with the productivity and simplicity of the MIG process, Waldock adds.