For every outdoor sport, there are "super fans" so devoted to a certain brand that for them, brand and sport seem intertwined. Often the brand seems to define the genre. For bikers, it is nothing less than a Harley. For hunters, Winchester has set the standard for generations. Think baseball? Think Louisville Slugger. Hemingway wrote of it as "aficion" and said that for "one who had aficion he could forgive anything." In the world of shallow water boating, that aficion is being defined by Phantom Jet Boats. And as for forgiveness? Well that comes, too, courtesy of the high-tech coatings that are applied to the Jet Boat hulls. For those of you yet to become Phantom Jet Boat aficionados, here’s a brief description of the boats and their myriad uses. The shallow water aluminum boats are used by military, law enforcement, State Departments of Parks and Fish and Game, sport fishermen, and pleasure crafters. These boats are designed to go where no other boat can – including over sandbars, submerged trees, weeds, and shoals – and at high speeds. As Don Murphy, vice president and owner of Aztec Fabrication, the manufacturer/coatings contractor crafting these vessels, says, "Our Alaska customers refer to us as ‘the Harley-Davidson of jet boats’—a comparison we are profoundly proud of." But what is it that gives these "watery Harleys" their edge? It is the unique coating protecting their hulls. And the story of the coating is a story of aficion as well. A PASSIONFOREXTREMES: SPEEDANDCOATINGS Murphy is a serious, plain-spoken man. Not one that you’d easily imagine speeding over Alaska’s most unforgiving inlets or over the rocky shoals of Washington’s coastline, and yet he does. Behind his quiet demeanor lies the authority of a man at the peak of his craft. "We’ve been building this style of boat since 1998," he says. "They are just starting to catch on now." As we speak, he has two vessels in his Washington-based shop: a 21' (6.40m) boat for the Arizona Fish and Game Department and a 21' (6.40m) boat for the Alaska Park Service. Both feature aluminum hulls. Both will be coated with K5 polyurea from Specialty Products, Inc. (SPI). And from the sound of it, this is a familiar scenario for him. It seems K5 is changing the Phantom Jet Boat industry – decreasing costs and turn-around time, while increasing coverage and protection. "Initially, we used to coat the hulls of our jet boats with ultra-high molecular weight (UHMW) polyethylene plastic or high-density polyethylene (HDPE) because it would withstand the abuse from the gravel bars in Alaska," Murphy explains. UHMW and HDPE allowed the boats to "slick over the sandbars and rocks, but they had to be welded if any repairs needed to be made." This would ultimately represent lengthy down-time for the vessel – an inconvenience to a private owner, and a real problem for law enforcement and the military. Searching for alternatives, Murphy discovered SPI and K5. The chemists at SPI share Murphy’s inquisitive nature and a 20-year-long involvement in the marine industry. According to Cliff Haskins, vice president of marketing for SPI: "In the mid to late 2000s, SPI undertook a three-year-long research and development process to bring the K5 polyurea to the market. It was discovered through a client field experiment that the coating also offered protection for vessel or boat hulls against abrasion or impact damage." As luck would have it, SPI was already working with Murphy on other coating applications. "Murphy approached SPI and asked about a coating solution to replace the UHMW and HDPE liners that Aztec was using on hulls," Haskins says. And thus, sport met science in the perfect blend of aficion. "An ultra-high-strength, high elongation polyurea, K5 was originally developed as a blast-resistant polymer," explains Haskins. "Soon after, it was discovered that K5 is exceptionally resistant to abrasion compared to other spray-applied coatings. And it can be spray-applied to virtually any surface configuration, to any thickness. So, it can be selectively applied to high-wear areas." With a tensile strength greater than 5500 psi, the 100 percent solids, pure polyurea seemed like a perfect fit, but Murphy wanted to be sure. "I sprayed the hull of a demo jet boat with K5 and ran it ragged for a year and a half," he says. "From that test, we decided it was a good alternative to the UHMW and HDPE. So I bought a machine, and we haven’t looked back." Murphy says he enjoys the ease of the K5. "Customers can get more coverage for less money. The UHMW and HDPE may be a little slicker on the rocks, but the K5 can actually be repaired by the customer using the EPl9 patch kit whereas the UHMW or HDPE must be professionally welded. The K5 is actually stronger than the UHMW or the HDPE. It bonds like a glove to the aluminum. And it is more forgiving. Dents can literally be hammered out using a rubber mallet." LIKE A RUBBER BAND So just how is this high-tech coating applied? Is the process as finicky as the cured coating is tolerant? Not at all. First, Murphy fabricates the aluminum boat hull, which is then brought into the well-ventilated spray room. Although the K5 has no VOCs or solvents, Murphy and his partner wear PPE, including respirators, Tyvek suits, goggles, and rubber gloves. The hull’s aluminum surfaceis then abrasive blasted to achieve a minimum 4-mil (0.10mm) anchor profile. Next, the area to be coated is masked off using masking tape. And the pigment of choice is added to the B-side of the Graco HXP 2 drum proportioner. SPI’s AE-4 adhesion enhancer is also added to the B-side of the drum and allowed to mix for approximately 30 minutes. The AE-4 admixture helps form a chemical adhesive bond to a properly prepared substrate and eliminates the time consuming process of applying a primer. Haskins notes that the minimum processing parameters for the proportioner are 2500 psi and 160°F to 170°F (71°C to 76°C). "They use a Graco Mechanical Fusion gun with a 27-27 mixing chamber and a flat tip as well as 50' (15.24m) of heated hose." Murphy says that the K5 is typically applied at 100+ mils (2.54mm) in low and shallow areas on hulls. High abrasion areas receive 120+ mils (3.05mm). "The number of passes applied depends on the customer. We can spray it on as thick as they want. The thickest I’ve ever applied is approximately ½" (1.27cm) and the thinnest is about 1/8" (0.32cm)." When the Aztec crew spray-applies the K5, they "use a cross-hatch pattern, spraying the hull lengthwise first, then across, then lengthwise again," Murphy describes his technique. "We create a woven pattern, which makes the hull snap back into shape on impact, like a rubber band." Haskins agrees. "Spraying north-south-east-west gives optimal product thickness control and coating uniformity." Then Murphy waits approximately 45 minutes to one hour before de-masking the hull and returning the boat to the production process.

About the Author

Daniel Mark Robert always write about thermal barrier.This article is a guide to abrasion resistant coatings.

Your Response