1 / 33

B 1

M. G 3. Z 3. Z. G. Z 2. G 2. B. B 1. Lesson 4.3. Loose Water. References. NSTM 079 Volume 1 NTTP 3-20.31 Damage Control Book, section II (a). ENABLING OBJECTIVES. Explain why FSE impairs stability. Compute FSE. List methods to reduce FSE. Explain why FCE impairs stability.

rusty
Download Presentation

B 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. M G3 Z3 Z G Z2 G2 B B1 Lesson 4.3 Loose Water

  2. References • NSTM 079 Volume 1 • NTTP 3-20.31 • Damage Control Book, section II (a)

  3. ENABLING OBJECTIVES • Explain why FSE impairs stability. • Compute FSE. • List methods to reduce FSE. • Explain why FCE impairs stability. • Compute FCE. • Describe pocketing, surface permeability, size of hole, and venting on FSE and FCE. • Correct stability curve for FSE and FCE.

  4. CLASS TOPICS 1. Free Surface Effect2. Example3. Free Communication Effect4. Example

  5. M M M M M M G G G G G G Z B B B B B B B1 B1 B1 B1 B1 FREE SURFACE EFFECT

  6. M M M M M M G3 Z3 G2 Z G G G G G G2 G2 G G2 Z2 G2 G2 B1 B B B B B B1 B1 B1 B1 B1 B FREE SURFACE EFFECT GZ2 = GZ3

  7. M G3 G B B1 GG3

  8. B3 x L MOMENT OFINERTIA = FSE= SHIP'S DISPLACED VOLUME 12 x 35 x Wf = FREE SURFACE EFFECT B= BREADTH OF COMPTL = LENGTH OF COMPTWf = SHIP'S DISPLACEMENT

  9. POCKETING - SHALLOW

  10. POCKETING - ALMOST FULL

  11. POCKETING (NO POCKETING EXISTS)

  12. SURFACE PERMEABILITY

  13. SLUICE VALVES - Closed

  14. SLUICE VALVES - Open

  15. FREE SURFACE EFFECT • Independent of the depth of the liquid • Greater w/ increased length and width of the compartment • Increases as draft decreases (de-ballasting) • Can be reduced by pocketing

  16. CLASS TOPICS 1. Free Surface Effect2. Example3. Free Communication4. Example

  17. AFT STBD 25 FT 4 FT PORT 30 FT FWD Wo = 3500 LT FSE?

  18. FSE = (30 FT)3 x 25 FT 12 x 35 FT3/LT x 3585.71 LT FSE = 675000 FT4 = 1505998.2 FT3 FSE = B3 x L 12 x 35 FT3/LT x WF .45 FT

  19. CLASS TOPICS 1. Free Surface Effect2. Example3. Free Communication4. Example

  20. M G B FREE COMMUNICATION EFFECT FREE COMMUNICATION EFFECT

  21. M G B FREE COMMUNICATION EFFECT FREE COMMUNICATION EFFECT

  22. M G5 Z5 G3G5 G3 G Z4 B G2 G4 B1 FREE COMMUNICATION EFFECT

  23. FREE COMMUNICATIONEFFECT Bx L x Y2 FCE= 35 x Wf B = BREADTH OF COMPTL = LENGTH OF COMPTY = DIST FM SHIP C/L TO COMPT COG.Wf = SHIP'S DISPLACEMENT

  24. FREE COMMUNICATION EFFECT(All 3 must exist) • COMPARTMENT OPEN TO THE SEA • COMPARTMENT PARTIALLY FLOODED • COMPARTMENT OFF-CENTERLINEOR “UNEVEN” ABOUT THECENTERLINE

  25. . . . Y = 0 NO F.C.E. • COMPARTMENT OPEN TO SEA • COMPARTMENT PARTIALLY FLOODED

  26. Free Communication Effect • Size of the hole will reduce FCE. (Formula assumes entire skin of ship is “open to sea”) • Venting will reduce FCE. (More air transfer = more water “communicating” into the compartment.) • Increases as draft decreases (de-ballasting) • Can be reduced by pocketing

  27. CLASS TOPICS 1. Free Surface Effect2. Example3. Free Communication4. Example

  28. Wo= 2880 LT L = 28 FT Depth = 4 ft B = 29 FT 40 ft 20 ft y = 20 ft – 14.5 ft y = 5.5 ft 28 FT 14.5 ft 29 FT wFLOODING = 28 FT * 29 FT * 4 FT 35 FT3/LT wFLOODING = 92.8 LT WF = W0 +wFLOODING = 2972.8 LT

  29. 29 FT x 28 FT x (5.5 FT)2 35 FT3/LT x (2880 LT + 92.8 LT) FCE = 24563 FT4 104048 FT3 FCE = B x L x (y)2 35 FT3/LT x WF FCE = .24 FT

  30. Quiz… • Why does FSE impair stability? • ANS: Horizontal weight shifts off centerline cause a “virtual rise” in G, reducing GM. • Factors that reduce FSE? • ANS: Compartment size, pocketing, baffle plates, surface permeability, sluice valves, venting. • Which variable is the “determining factor” in the FCE equation? • ANS: “Y” the distance from the ship’s centerline to the compartments center… it is squared.

  31. Quiz… • What three factors must be present for FCE to exist? • ANS: 1) Off centerline or Uneven about centerline. 2) Open to the sea 3) Partially flooded.

  32. Instructor will now… • Assign Practice Problems for lesson 4.3 (Stability Problems #4, #7. Try problems #8, #11) • Read Student Guide!! • Homework # 2 Due end of class TODAY!

More Related