Flex-Ride Night Raider 7m Widmer Boat: Impact comparison testing of HDXLPE and FRP.

Jan. 16, 2012 - PRLog -- ABSTRACT: Historically, boats made of wood, fiberglass or metals are rigid, providing no occupant protection from repeated wave impacts. The Widmer plastic hull flexes and absorbs impacts produced at high speeds in rough water: the impact G-forces are absorbed by the hull instead of directly translated to the occupants. The Widmer boat hull is double-wall rotationally molded out of high density cross-linked polyethylene (HDXLPE). It employs Widmer’s patented kiss-offs for strength. The kiss-offs are designed to produce a double-walled cross-section in high impact areas such as the hull bottom. Additional benefits of this polyethylene material are its toughness, the ability to absorb blunt impacts from rocks/debris, abrasion resistance and puncture resilience. Furthermore, HDXLPE resists cracking, does not corrode, does not need paint – and this material floats!

The test gear consisted of a vertical tube that contains a free falling weight.  The termination platform has an opening (throat) to allow the ball to penetrate beyond the termination platform plane.  The drop ball measured 1.0 inch diameter and the throat measured 1.738 inch diameter.  The vertical tube has a tape measure attached to it.  This test equipment can be seen in the upper right corner of the attached collage.  The ball is propelled by a cylindrical mass whose combined weight is 10 pounds.  The impact calculation becomes quite easy:  When 10 pounds is dropped from 1 foot, the impact at the termination plane is 10 foot pounds.  

The test was conducted with 10 lbs at 8 feet for 80 foot pounds.  To consider a more meaningful number, the 10 pound weight had a velocity of 11.34 ft/sec or 7.7 mph when it strikes the test material with the leading edge (point) of a ball.  The test materials consisted of 6" by 6" squares of 0.25 inch thick HDXLPE and FRP.  In the upper left corner of the collage, the HDXLPE absorbed the impact with only a slight dent as a witness mark.  The FRP (lower left) was punctured as was expected.  We wanted to determine how much impact FRP could take without failure.  In the lower right photo we successively used 7, 6, 5 and 4 foot drop tests.  Even at 4 feet (half the impact energy) the FRP fails.  Our hull material takes more than twice the impact without failure.  We are designing another test machine that can handle more than 80 foot pounds to determine the point of failure for our material.

This test demonstrates the survivability of boat hulls made from different materials when subjected to collision impacts.  When a boat hull impacts something in the water (rock/wood/debris) the forces placed upon the hull and occupants can range from injuries to hull rupture and/or failure.  When craft survivability is paramount to mission success, an impact resistant hull from Widmer is the solution.  Our boat hulls have more than twice the impact resistance of FRP.

The Flex-Ride Night Raider is the culmination of Stanley Widmer’s lifelong search for a better boat hull. Stanley’s boat racing experiences, marine industry experience and hull development are thoroughly covered in his book The Journal of a Businessman. Visit http://widmerboat.com/newspressreleases/journalofabusines...  The boat’s initial success has prompted interest from military, law enforcement and Coast Guards worldwide. Commercial applications are also being designed and reviewed.

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About Stanley Widmer Associates, Inc. We Design, Engineer & Manufacture with Advanced Methods and Materials. Stanley Widmer Associates, Inc., founded in 1971, has offices in Staples, MN and is a leader in the Rotational Molding and Marine markets. More information about Stanley Widmer Associates, Inc. can be found at http://www.widmerboat.com/ .