July 11, 2006
As aluminum becomes more and more readily available for various manufacturing applications, the boat-building industry is taking notice. To build its patented vessel design, Aluminum Chambered Boats has found that arc welding - both GMAW and GTAW - is a critical technology.
|U.S. Air Force security police use this response boat to conduct sea trials.|
Bellingham, Wash., has a long tradition of seafaring sailors and boat-builders. During the 1800s many full-rigged ships hauled lumber to places like California and Hawaii. During World War II wooden mine sweepers were constructed for wartime duty. Fiberglass river patrol boats were built locally for service in the Vietnam War. Numerous commercial fishing vessels and pleasure boats have come from Bellingham shipyards and plants.
Boats of all types have been made from wood and steel over many years, but as aluminum becomes more and more readily available for use in all types of manufacturing, the marine industry has taken notice and, for years now, has incorporated this metal into ship designs.
But Aluminum Chambered Boats (ACB) builds its patented line of aluminum craft—which range in length from 20 feet to 32 ft.—differently. These boats, known for being durable and virtually unsinkable and for requiring minimal maintenance, are being used to support homeland security for port and border patrol, by commercial fishermen, and for recreational use. Several engine options are available, including outboard engines and inboard/outboard configurations.
|Top: Gas metal arc welding is used here to tack the stringers into the hull of a vessel. Bottom: In-house design chief Rick Benson (left) and his team study a shop floor modification on a 26-foot boat.|
"It's [aluminum's] light, strong, 100 percent recyclable, and holds up very well in the hostile marine environment," said Craig Adams, director of operations for the company. "For boats of this nature, when you consider the strength and weight issues, it's one of the best materials out there."
A special design feature of these vessels is incorporated in the company's name: chambered. Along both sides of the hull, which is constructed of welded aluminum, are sealed and bulk-headed chambers. These are what make these vessels essentially unsinkable even if they're raked by small-arms fire or if they hit an underwater obstruction, such as a reef.
Seventy employees fabricate most of the ships' components in two buildings, which cover 72,000 square feet on Bellingham's waterfront. Outside vendors form the aluminum chambers.
The company has undergone many changes in the manufacturing technologies it uses. In the last year the company has moved from hand-cutting parts in-house to CNC waterjet cutting through an outside vendor. Patterns are documented into CAD, which facilitates outsourcing.
Once cut, the parts are packaged in kit configuration for each specific boat to help ensure accuracy and speedy assembly. The basic hull assembly is modular in concept and involves one of the company's three building jigs.
|Fabricator Charles Wagner uses specially designed clamps to position the hull plates on the chambers in a jig before they're welded together.|
Made with T-bar hull stringers and a ladder-type frame under-deck substructure, the vessels are designed to reduce pounding and enable the operators to return promptly to port during turbulent sea conditions. Such features have made these boats popular with Alaskan fishing lodge operators as well as U.S. Navy SEAL units.
Gas metal arc welding (GMAW) comprises 70 percent of the welding done on these boats; gas tungsten arc welding (GTAW) makes up the other 30 percent. One hundred percent argon is used for shielding. The hulls are fabricated with 1/4-inch-thick 5086 alloy plate, and the chambers with 3/16-in.-thick 5052 alloy. Piping and small parts are welded using GTAW, primarily 5356 wire, and argon gas.
Before the vessels are painted, they first are acid-etched. Then, in a fully filtered and enclosed paint booth, a sealer coat is applied, followed by a polyurethane topcoat. Getting paint to adhere to aluminum in a hostile environment for the long term is difficult, but the company continues to test coatings to ensure the best finish available. The company also welds accessories, such as cleats, to the boats wherever possible to avoid corrosion or electrolysis problems with fasteners.
|Painting is performed in an environmentally controlled booth with the painter wearing an air-supplied helmet. Long-lasting polyurethane paint is used.|
Of course, critical welding skills are necessary for any aluminum welding, and marine welding is no exception. As the entire manufacturing industry faces a skilled work force shortage, the company partners with local educational institutions and plans to offer on-site training to help recruit and maintain the skilled labor force it needs.
And with sales doubling each year, the company needs to continually develop and maintain its dynamic employee team.
"We have a healthy backlog of orders for our aluminum chambered vessels," Adams said, which has been generated by a topnotch professional work force putting out a high-quality fleet of vessels."
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