Ship Fender Development Program
Sea Systems Group, Inc. is working to develop the advanced MitiGator Ship Fendering System (MSFS)where MitiGator™ technology is used inside fenders to separate ships at sea in skin to skin transfers. The MSFS has developed under ONR subcontracts from Oceaneering International for the STLVAST project and Lockheed Martin (LM) on the Phase I HiCASS LVI LO/LO project. Sea Systems Group, Inc. is working with a team to develop and implement this technology.
The design has been developed based on the information contained in Fender and STLVAST, HiCASS Reports, experience of others knowledgeable in the area, input from LM team members and Sea System's experience with The MitiGator™ technology. The system combines innovative and proven technologies. MitiGator™ layers are inside a pneumatic fender which provides the technology that will be used in the MSFS.
The MitiGator™ technology dissipates 40-60% more energy than other cushioning technologies, including state-of-the-art foams. It reduces loading as much as 4 - 8 times more than foams. This system will prevent ship damage, reduce relative ship movements, work with mooring system to keep ships skin to skin, and assist in keeping ships acting as one during maneuvering.
After repeated testing, The MitiGator™ dissipates more impact energy than any other passive fender systems. The MitiGator Hybrid Fender System provides system in system protection, safe ship separation with lots of reserve capability, improved ship stability, lower reaction forces, less weight than foam filled fenders, reduced storage space requirements, elimination of chain and tire net, easy and quick installation deployment, rub rails provide reduced damage to fender and ship, long service life with replaceable low friction rub rails and easy repair, and accessories that facilitate varying hull angles and sea conditions.
Using a material formed into air cells and channels, MitiGator™ dissipates as much as 40% (Navy Horizontal Accelerator test results) more of the applied impact energy by shunting air through channels in a controlled manner. In testing performed at NAVAIR’s Human Systems Test Facilities Horizontal Accelerator, a MitiGator™ cushion reduced the lumbar load by a factor of 4.5 to 8.8 times (X) more than a visco-elastic style cushion, when both were compared to the current cushion (reference). Developing fenders based on the MitiGator™ technology to attenuate impact energy during STLVAST operations can dynamically reduce the relative motion between the ships.
Transitioning the proven MitiGator™ technology from a "waffle" based technology to a film-based MitiGator™ technology that will lend itself to variable inflation as part of a total MSFS will result in a weight reduction of about 85%, a cost reduction of about 50%, and a more compliant MitiGator™, which can conform to slightly curved shapes without losing its effectiveness. There are several additional advantages to the film approach for making MitiGators™. First, the potential is there to reduce thickness or increase energy dissipation in the same thickness because there will be more air and less material per cubic foot when compared to "waffle" technology. Second, because energy is dissipated through controlling the air through the MitiGator™, it will be much more effective on a per pound basis. Third, it can be readily inflated and pressurized for adaptability during STLVAST operations and deflated for storage.
A hybrid fender, made up of MitiGator™ sandwiches and air chambers can be stored in a smaller volume, inflated to its full useful cross-section, positioned over the side of the MLP, and absorb the potential forces projected for joint ship operations during missions in sea states up to and including sea state 5.
One third scale MitiGator™ models of the MSFS were constructed during 2008. The MitiGator™ models are 78" x 39" x 4" with an average thickness of 1/16". The individual half layers weigh approximately 45 pounds, for a combined total of approximately 90 pounds per layer. The MSFS is an ongoing program at SEAS. We expect to complete some in house testing of the MitiGator™ scale models layers of the MSFS during 2009. Check back for updated information as this program moves forward.
The above picture shows the size of the 1/3 scale MitiGator™ layers prototyped in 2008.
This picture shows a 1/3 scale MitiGator™ layer inflated for evaluation.
