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Ship to Ship Hydraulic Stabilizer for Cargo Transfer pt 2


The RG Group team created a new large vessel interface for “lift-on lift-off” exchanges at sea for the US Navy. Engineered Assembly VP of Manufacturing Ed Stum and Engineer/Project Manager Dave Hoke fill us in on some of the insider details about the design and installation of this unique system.

RG Group’s VP of Manufacturing and Engineered Assembly, Ed Stum, sits down to talk about some of the opportunities and challenges we faced creating this Ship to Ship Hydraulic Stabilizer. The first challenge we faced was the sheer size of the system, this was one of the largest systems we’ve ever built. Half of our production shop was consumed with this project, there were 6 different systems each having 6 inch cylinders with 8 foot stroke and 20 feet of cylinders in motion. Each had 600 gallon reservoirs with 2 500 horse-power motors, a very sizeable power unit to say the least. Additionally, the power requirements were large and used just about every one of our manufacturing capabilities. We had metal cutting and fabrication, welding, and system assembly with some very large components. Utilizing every bit of our overhead cranes we did marine grade epoxy painting, a large amount of hose assembly with 2 inch hoses as well as high pressure and high volume hoses, and very sizable bent pipes and poles.

Engineers, project managers, control specialists, and other Navy personal had access to our facility which meant we had to be flexible and step up our housekeeping and security. But flexibility really is one of our core strengths. We were able to open the shop up to a very large project like this while at the same time in other areas of the shop we were working on several small projects at once. We have the ability to set up flexible manufacturing cells to accommodate high volume projects of this size and greater which gave the customer a fairly significant comfort with our ability to get the job done.

Dave Hoke, Lead Engineer and Project Manager for this project, talks about the process of making sure the system was the perfect fit for what the Navy needed. Based on the first round of calculations we determined that the system was too large for the capacity of the ship that we placed it on so we had to do some redesign, we decided to go back to a smaller sized cylinder to reduce the flow requirements from the HPU itself. Even with doing that it was still too large, so we determined to offset some of the horse power requirement with stored energy accumulators. The one thing adding accumulators did was it added weight to the structure itself which reduced the lifted capacity so we had to come up with a balance between all those factors to determine the actual system we ended up with. We actually were able to do the final installation and commissioning of this system.

The installation might have been the most challenging part of this entire project but it certainly was one of the most fun parts of the project as well. We had to be completely self-sufficient on a navy vessel for a series of weeks to do a wide variety of tasks. Hose making and hose crippling with very large hoses, fabricating of brackets, welding the brackets onto the structure of the ship itself, and even just keeping warm were some of the challenges we faced. We did this installation in the winter at port on the Chesapeake Bay so the weather was freezing and in order to survive and work on the vessel the RG Group procured a vehicle and a customized enclosed trailer that we set it up as a mobile work shop for the workers on board. We had to modify that trailer so that it could be lifted up onto this Navy ship, secured down, and reside there for several weeks.

We put several groups of workers on board including service technicians and engineers for a period of weeks to install this large system. We had people 60 feet up in the air using the highest part of the crane, we then put the cylinders down at the working head of the crane and then had yards and yards of inter-connecting hose and tubing between the two. Every bit of that had to be checked and rechecked. The Navy was adamant we couldn’t have oil leaks on their deck or in the Chesapeake so we did full system testing on board the ship. This included pressure testing every line, torqueing every screw and fastener, and double checking everything to make sure that at system start up there would be no leaks with this system. Once we finished testing everything and making sure no oil was on the vessel’s surface or in the Bay we did the installation. We had engineers on board to support the system startup which it all went very smoothly and successfully. This was a really great experience for RG Group and we are very pleased at how everything worked out.

To learn more about us visit our website at or call us at (717) 846-9300.

RG Group
650 North State Street
York, PA 17403

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