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Snag Boat Final Presentation

Eric Speight Matthew Funk Courtney Johnson. Snag Boat Final Presentation. Outline. Introduction Problem Proposal Solution Accomplishments Center of Mass Calculation Buoyancy Force Calculation Structural Properties Deck Strength Calculation Patran Analysis of Proposed Changes

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Snag Boat Final Presentation

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  1. Eric Speight Matthew Funk Courtney Johnson Snag Boat Final Presentation

  2. Outline • Introduction • Problem • Proposal • Solution • Accomplishments • Center of Mass Calculation • Buoyancy Force Calculation • Structural Properties • Deck Strength Calculation • Patran Analysis of Proposed Changes • Conclusion • Complications • Gantt Chart • Questions

  3. Introduction What is a Snag boat? Traditional use of the ROS Snag boat was to clear debris from rivers for safe navigation.

  4. Introduction The JRRF is located at FT. Eustis in Virginia.

  5. Introduction • JRRF use • To maintain and inspect moorings. e.g. Anchors, chains.

  6. Problem.. • Crane failure due to an excessive load.

  7. Problem continued.. • Non-operational snag boat due to broken crane • No usable space for the JRRF to operate

  8. Problem.. • Picture of Current snag boat.

  9. Proposal • Make the vessel more usable • Remove second level • Remove portion of first floor • Move wheel house to rear on first floor • Relocate crane to accommodate deck space for mooring inspection. • Assure that integrity of vessel is uncompromised

  10. Proposal

  11. Solution We needed to see if these modifications were even possible without seriously damaging the structural integrity of the boat. We calculated the center of mass of the boat, as well as the upward buoyancy force. Deck strength Analysis Patran Analysis of section before and after modifications

  12. What we have accomplished • Developed website • Center of mass before and after modifications • Buoyancy force • Gathered information regarding structural analysis of ships • Determined beam properties applicable to our ship

  13. What we have accomplished • Analyzed the deck strength • Analyzed the proposed modifications in Patran

  14. Center of Mass Calculation Baseline (82 , 5, 21) Proposed(81, 4 ,21) Baseline with Load (93, 6, 21) Proposed with Load (93, 6, 21)

  15. Buoyancy Force Calculation • 1170 tons • Buoyancy is an integral part of determining still water moment

  16. Structural Properties • Information for all L beams on ship • Steel plating thickness, weight, etc.

  17. Deck Strength Calculation • Assumed the deck to be made out of G10180 Cold Drawn Steel • Width = 40ft • Thickness = .25 in • Compared it to stress calculated using F/A • Force is weight of chain link and anchor • Calculated the cross sectional area of a chain link and anchor on the ship deck

  18. Chain Link • Used a 5-1/4 open link chain • Weight of 1 Link = 440lbs • Width of link = 31 inches

  19. Anchor • Assumed a 10,120 lb anchor • Width of anchor: 94.0625in

  20. Comparing Results • Max yielding strength value: • Maximum Yield Stress = 54 kpsi • Modeled the deck as a simply supported beam with a cross sectional area of: • A = (width of chain + width of anchor)*(deck thickness) • A = 31.265 in^2 • σ = W/A = 337.75 psi • Therefore the deck can handle the stress

  21. Deflection of the Deck • Modeling the deck as a simply supported beam where: ∆ = 5PL^4/384E*I • Calculated moment of inertia by using deck thickness/width • I = 2.304e 6 • E = 30 e 6 psi • ∆ = .10569 in

  22. Patran Baseline

  23. Patran • Proposed

  24. Force • Divided buoyant force by the foot print of the ship. • Yielded 344 lbs/sqft • Applied 100 lbs/sqft to the bottom 5 ft of the sides of the hull • Applied the density of A-36 steel to the model

  25. Baseline Isometric Displacement Max Deformation 0.184 Feet

  26. Proposed Isometric Displacement Max Displacement 0.0936 Feet

  27. Baseline Stress Tensor Maximum Stress 2.27e6 psf

  28. Proposed Stress Tensor Maximum Stress 1.88e6 psf

  29. Safety Factors • A36 Yield Stress of 5.22e6 • Baseline • 2.3 • Proposed • 2.9

  30. Structural Pro’s Estimated weight removed would be 63,000 lbs Hull beams will remain untouched. They have the highest load on them. • Removing weight but maintaining integral parts of the structure • No beams will be swapped out for smaller ones

  31. Stress Structural Con’s Stress concentration located right on the section where we stopped modeling

  32. Structural Recommendations/Final Thoughts • Safety Factor is low, a ship that is loading and unloading should have a high safety factor (approx 6) due to fatigue • Entire ship needs to be modeled in ten foot sections

  33. Initially no clear direction After some discussion we came to the realization of what we needed to be done. Complications

  34. Gantt Chart

  35. Any Questions??

  36. END

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