Application Stories

Silver Ships Improve Quality and Reduce Costs With New Pulsed MIG Systems

As a supplier to the Coast Guard and other state and governmental agencies, Silver Ships Inc. of Theodore, Alabama, must produce top-quality aluminum boats that can stand up to the rigors of rough seas and poor weather conditions. These boats are utilized for search and rescue missions as well as for law enforcement. Since welding plays a major role in boat production at the company, creating high-integrity welds is of the utmost importance.

"We won't buy a machine unless we can test it in our shop," noted McCarty. "Our local Lincoln representative, Troy Gurkin, let us weld with the Power MIG: The Professional Choice, 300 for a few weeks and we could definitely see the quality difference - it is this trial that sold us on the machine."

Recent growth necessitated that the company purchase new pulse MIG welding equipment. In doing this, 17-year-old Silver Ships moved away from its traditional welding set-up to the new Power MIG™ 300® from The Lincoln Electric Company. The decision was made to invest in these units because they produce better quality welds while at the same time simplifying operator set-up – all for a price tag that is significantly less than traditional push-pull pulse systems

silver ships produces aluminum boats"Previously we were utilizing a power source, wire feeder, push/pull gun, water-cooler and external pulsing pendant for our pulse MIG welding," said Mike McCarty, Owner of Silver Ships Inc.. "This set-up not only left us with quite a few components to purchase, but also required highly-skilled welders to be able to set all the complicated parameters and make a good weld. But since the Power MIG 300 offers pulsing capabilities built-in, an integral wire feeder and a direct plug-in for our Cobra push/pull gun, we have been able to eliminate a number of components. By reducing the number of components, it was much more cost effective for us to go with the Power MIG 300."

But McCarty is quick to point out that cost savings is not the only reason his company chose the Power MIG 300. "The quality of the weld is what is really at the heart of the matter for us at Silver Ships," noted McCarty. "The Power MIG 300 is able to produce higher-quality welds with less warpage and burnthrough. With charts on the unit that tell operators which settings to use as well as a one-knob control, the Power MIG 300 has taken the 'art' of welding and made it more scientific. It also allows us to make repeatable, consistent welds."

In the switch, the 30-employee company found that the Power MIG's patented Pulse-On-Pulse™ process allowed the switch to a lower amperage weld procedure than previously used. In this particular application, this enabled Silver Ships to switch from a water-cooled to an air-cooled torch. Eliminating the water-cooled torch significantly reduced the cost associated with maintaining water- cooled MIG guns. Silver Ships also discovered that it could virtually eliminate grinding since the Power MIG 300 has better arc starts and stops and does not leave the telltale "ball" at the end of the weld. According to McCarty, with the previous systems grinding was a necessity.


Lincoln's Power MIG systems provide quality welds for Silver Ships

 Boat Manufacturing

Boats produced by Silver Ships range from 20 to 50 feet long and take an average of six to eight weeks to complete. The company produces a number of different types of heavy industrial boats including patrol, pilot, engineering, environmental, and oil spill boats, among others. Each boat is custom-made based on how the finished boat will be used and outfitted with such items as tow reels, pumps, and fire equipment. Whereas a recreational boat may see 100 hours of use in a three-year period, boats supplied by Silver Ships are in constant use – sometimes even 24 hours a day in poor conditions – adding up to thousands of hours of use in a single year. This heavy use further dictates quality.

Silver Ships takes the aluminum boat manufacturing process from plate and extrusions to a finished boat product. To do this, the aluminum plate and extrusions are cut and formed (both by hand and with jigs), then cleaned and welded to form the hull. Once all welding is completed, the boats are sent out to be sandblasted. When they arrive back at the Silver Ships shop, the vessels are acid-etched to remove all contaminants and residues. In the final steps, the boats are painted with zinc chrome, high-epoxy paint and urethane. Electronics, motors, windshields, handrails, bells, and other accessories are then installed.

Silver Ships takes the aluminum boat manufacturing process from plate and extrusions to a finished boat productAll boats must undergo rigorous sea trials to test their worthiness before leaving the Silver Ships plant. "I build every boat like I'm building it for my own use," claims McCarty. "That is how exacting we are on getting it right."

Boats are built to American Bureau of Shipping (ABS) and the Yacht Council standards. In addition, Silver Ships has obtained the status as a Solas builder meaning that its products have undergone Underwriter Laboratory (UL) inspection.

Welding Work

Welding is at the heart of all the production work at Silver Ships. McCarty estimates that each boat manufactured by the company is held together with thousands of feet of weld metal – and that is why finding quality equipment is so important.

When Silver Ships representatives began looking to purchase new power sources, they did investigate competitive models, but ultimately were swayed by the quality, fewer number ofcomponents, and overall cost of Lincoln's Power MIG 300. "We won't buy a machine unless we can test it in our shop," noted McCarty. "Our local Lincoln representative, Troy Gurkin, let us weld with the Power MIG 300 for a few weeks and we could definitely see the quality difference - it is this trial that sold us on the machine."

Because all of the welding performed at Silver Ships is on aluminum, the Power MIG 300's synergic pulse capabilities make it the perfect machine for this application. It allows for true aluminum pulse and pulse-on-pulse welding. By utilizing Lincoln's Chopper Technology™, the Power MIG 300 offers a smooth, stable arc with improved arc starts.

For feeding aluminum wire, the machine's built-in feeding in constant torque mode allows it to push the soft wire, while at the same time, the Cobra gun controls and maintains a constant speed of the drive motor at the gun to pull the wire. The result is the ability to feed aluminum wire long distances reliably and flawlessly.

Power MIG welders from Lincoln reduce burnthrough and warpage"One of our biggest challenges with welding is that we have a number of different people welding on one boat and we need to have consistency so that someone who looks at the boat, will not notice any difference in the welds from one area to another," said McCarty. "Since the Power MIG 300 is easy to use, all of our operators can make high-quality welds."

The Power MIG 300 unit is operated with a one-knob control, allowing the user to set parameters such as wire feed speed. The unit will automatically adjust itself to the corresponding proper voltage and will constantly monitor the changing characteristics of the arc. This one-knob synergic control means that it is easier to use and can quickly change between settings if the operator needs to work on a different area of the boat with a different aluminum thickness. "It is the most user-friendly piece of equipment in welding that we've ever used," said McCarty. "Its user-friendly design means that our operators are spending more time welding and less time setting up."

According to McCarty, in the past the company had constant problems with heat input. "The Power MIG 300 is able to produce a special aluminum pulse-on-pulse waveform , which reduces heat input and it also reduces a lot of reflected heat. We are now running at 30% less amps which means we are burning up fewer tips and nozzles," notes McCarty. "The unit has also helped reduce burnthrough and warpage - even on thin aluminum which is prone to these problems."

Another problem eliminated by the Power MIG 300 is that of cabling on the floor. With the previous set-up, Silver Ships had many cables strewn on the shop floor. The Power MIG's set-up only has one cable - so it eliminates clutter and safety hazards associated with the former welding systems.

But more than anything else, the Power MIG 300 can provide quality operation. "It is hard to find skilled welders, but what this machine does is take an operator at almost any skill level and make him or her a better welder," explained McCarty. "We are getting extremely good quality, and we have decreased undercut. The visual appearance is smooth with a uniform edge that ties-in and blends. Welding is the most important thing we do here - our boats must survive what our customers put them through."


Silver Ships primarily utilizes 1/8" through ½" marine grade aluminum in its manufacturing operation. Welding operators at the company are required to make all types of welds - fillets, laps and butts - in all positions.

Quality welds produce a visual appearance that are smooth with a uniform edge that ties-in and blendsSilver Ships utilizes MIG welding for about 90% of the total ship structure, including the hull, bulkheads and longitudinal stinger. TIG welding is used for just a small portion of the welding such as hand rails and other areas where intersections make it difficult to use MIG because of the tight fit required for the welding torch. "We are trying to move some of these items from the TIG process to the Power MIG," explained McCarty. "We are currently testing our wheel houses and some other areas and hope to move more and more to MIG in the future."


As Silver Ship's older model power sources need replacing, McCarty plans to switch the entire shop to the Power MIG. Currently the plant is undergoing an expansion. Business has been up since September 11 as more and more boats are needed to patrol U.S. waters.

"I have been extremely impressed with the operation of the Power MIG 300 and also the immediate service provided by Lincoln," noted McCarty. "I look forward to a continued relationship with the Lincoln Electric company."