1 3 Dynamic Stability

Views:
 
Category: Entertainment
     
 

Presentation Description

No description available.

Comments

By: Hunterye (118 month(s) ago)

Great Explanation. Thanks

Presentation Transcript

Slide1: 

DYNAMIC STABILITY LT Tom DeNucci (860) 444-8672

Slide2: 

G Station Coos Bay 47’ MLB training Nov 1999

Dynamic Stability Objectives: 

Dynamic Stability Objectives Understand heeling moments Determine dynamic stability Determine max roll from righting and heeling moment curves Understand the Navy Criteria for dynamic stability

Heeling Moments: 

Heeling Moments Moments of forces are what cause a ship to heel, list, return to equilibrium or capsize. A righting moment tends to rotate a vessel towards its initial position A heeling moment tends to rotate a vessel away from its initial (stable) position. Causes of heeling moments Off-Center Weights Beam Winds Off Center Weights (Weights over the side) High Speed Turns Crowding of passengers Icing

Heeling Moment Curve: 

Heeling Moment Curve Plot of the Heeling Moment versus angle of heel, for any externally applied force. Heeling Moment curves usually start at a maximum value, and then decrease to zero at 90 degrees of heel.

Slide6: 

Angle of Heel Heeling Moment Curve (From - wind, turns, etc.) Moment

Static Stability Curve: 

Static Stability Curve Area under the curve represents work performed to heel the ship and stored energy available to return the ship to 0.

Righting Moment Curve: 

Angle of Heel Righting Moment Curve Righting Moment Curve Moment

Slide9: 

Angle of Heel Heeling Moment Curve Moment Righting Moment Curve

Slide10: 

Angle of Heel Moment Excess Heeling Energy

Slide11: 

Angle of Heel Moment Excess Heeling Energy Excess Righting Energy

Slide12: 

Angle of Heel Moment Excess Heeling Energy Excess Righting Energy Max Angle of Roll The ship will roll until excess heeling energy equals excess righting energy

Slide13: 

Angle of Heel Moment Excess Heeling Energy Excess Righting Energy Max Angle of Roll Static Angle of Heel If everything stays constant, the ship will settle out to a constant angle of heel

Slide14: 

Angle of Heel Moment Excess Heeling Energy Excess Righting Energy Excess heeling energy greater than excess righting energy Ship will capsize

CGC JARVIS - November 15, 1972: 

CGC JARVIS - November 15, 1972 Prior to damage Added weight only Added weight & Free Surface Effect Dynamic Stability curve

CGC JARVIS - November 15, 1972: 

CGC JARVIS - November 15, 1972 Prior to damage Added weight only Added weight & Free Surface Effect Max roll Dynamic Stability curve Heel

U.S. Navy Criteria: 

U.S. Navy Criteria In 1960’s, U.S. Navy developed dynamic stability design criteria for their ships Compares energy used to heel the ship to energy available to right the ship Applies a safety factor to ensure positive dynamic stability Similar criteria used by shipbuilders worldwide

U.S. Navy Criteria: 

U.S. Navy Criteria Navy criteria addresses specific hazards We’ll briefly look at criteria for: Beam winds with rolling Operating with a weight over the side High speed turns Crowding of Passengers to one side

Beam Winds With Rolling: 

Beam Winds With Rolling DRAFT H - LEVER ARM (feet) - From Center of SAIL AREA to 1/2 DRAFT A - SAIL AREA (square feet) [cross-hatched area] Vw - VELOCITY of WIND in knots H HEELING ARM created by WIND = 0.004 V A H 2 w 2240 ² cos ø 2

Beam Winds With Rolling: 

Beam Winds With Rolling

Weight Over the Side: 

D D Weight Over the Side

Weight Over the Side: 

Weight Over the Side Stability Criteria: 1 (Angle of Heel at Point C)  15 A1 (Excess Righting Energy)  40% A2 (Total Righting Energy) c) Righting Arm at Point C (RA 1)  60% of Maximum Righting Arm (RA 2)

High Speed Turn: 

High Speed Turn

High Speed Turn: 

High Speed Turn Stability Criteria: a) 1 (Angle of Heel at Point C)  10 for Newly constructed ships 1 (Angle of Heel at Point C)  15 for Existing ships b) A1 (Excess Righting Energy)  40% A2 (Total Righting Energy) c) Righting Arm at Point C (RA 1)  60% of Maximum Righting Arm (RA 2) A1

Crowding of Passengers: 

Crowding of Passengers D

Crowding of Passengers: 

Crowding of Passengers Stability Criteria: 1 (Angle of Heel at Point C)  15 A1 (Excess Righting Energy)  40% A2 (Total Righting Energy) c) Righting Arm at Point C (RA 1)  60% of Maximum Righting Arm (RA 2)

87’ WPB addition: 

87’ WPB addition Does this meet Navy Criteria? Not all the time!

authorStream Live Help