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Lifeline Systems

Lifeline Systems. Design Considerations and Lessons Learned Presented by: Paul H. Miller Assistant Professor US Naval Academy IBEX 2000. (sometimes the hard way!). The Big Picture.

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Lifeline Systems

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  1. Lifeline Systems Design Considerations and Lessons Learned Presented by: Paul H. Miller Assistant Professor US Naval Academy IBEX 2000 (sometimes the hard way!)

  2. The Big Picture “Lifeline systems discourage (but don’t prevent) the movement of people or items between the deck and the surrounding environment.” This applies in both directions!

  3. Who Needs Them?

  4. Designers and buildershave to ask, “Is a lifeline system appropriate for my design, and if so, what type should I use?”

  5. Factors To Consider:Stability

  6. Function

  7. Aesthetics

  8. Other Factors • Crew Ability • Inshore/Offshore Operations (expected weather vs. vessel motions) • Maintenance • Regulations • Legal Precedents

  9. Wire Gates Terminals Toe rails Bulwarks Foundations Deck structure Stanchions Pulpits If the answer is “yes”…Lifeline systems include:

  10. Lessons Learned:The US Naval Academy/US SailingLifeline Failure Study(The State of Current Designs)(1996-1998)

  11. Participants • Midn Savery (96) • Midn Mendez (96) • Midn Keller (96) • Midn Hanley (96) • Midn Anne Palmer (97) • Midn David Dees (97) • Midn Cris Neish (97) • Midn Thomas O’Malley (97) • Midn Patrick Saxton (97) • Midn Tawnya Tschache (97) • Prof Tom Butler • Mr Ralph Naranjo • Mr Tom Carr • Mr Ron Pitt • Mr Tom Stallings • US Sailing • Navtec • Cruising Club of America

  12. Documented Failures 1995-96 • Annapolis, MD • Key West, FL • Block Island Sound, RI • Lake Michigan, IL • Boston, MA • others? In 1998 Sydney-Hobart Race, lifeline systems were the 3rd most common failure, after sail and rig damage.

  13. Project Goals • Determine failure modes of Navy 44 lifeline systems • Improve reliability and capability of current systems • Provide recommendations for lifeline system design

  14. The Navy 44 Sail Training Vessel • Used to train Midshipmen in offshore seamanship • LOA 44 feet • Beam 12.3 feet • Draft 7.25 feet • Disp 27,654 lbs • Ballast 12,310 lbs

  15. Navy 44Seaworthiness and Safety Paramount Notice the vertical components of pulpits

  16. A Full-Scale Frame Simulated The Deck

  17. Welded of Mild Steel and Instrumented With Load Cells and Strain Gauges

  18. Socket attachment assumed the deck would not fail. • Valid for Navy 44’s, but not for all boats!

  19. Test Jig • 12,000 pound force • 1/4” and 3/16” wire • Strain gauges on stanchions and pulpits • Load cells and angle meters

  20. Results • Stanchions and pulpits failed first (1,000 pounds) • Wire terminals failed second (3-5,000 pounds) • Wire failed third (6-7,000 pounds)

  21. Pulpit Results Testing... Reality!

  22. Pulpit Design • Critical to overall system design • Maintain continuity • Use diagonals to transmit loads in compression rather than bending • Don’t clutter with other equipment!

  23. Recommendations • Use quality, uncoated 1x19 wire • Avoid gates • Check deck construction for adequate stiffness and strength (add backing and/or top plates if needed) • Meet Offshore Racing Council Special Regulations (even for non-sailors) • Keep lifelines taut • Inspect and maintain

  24. Taut Lifelines Reduce Loads on Individual Stanchions Too Loose!

  25. Extra bracing may be required But it may cause a tripping hazard...

  26. Rule #1 when on a boat... Keep the boat between you and the water!

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