Lesson 4.4 Trim and Draft FP AP LCF MP

Class Topics Longitudinal Stability Terms Drag / Trim Longitudinal Weight Shifts Example Longitudinal Weight Adds/Removals Examples

AP MP FP DWL LBP

LCF - The Longitudinal Center of Flotation MP CFD LCF LCF - The Longitudinal Center of Flotation

MP FP AP LCF LCF

SHIFT - TA equals the longitudinal distance shifted Trimming Moment = w x TA TA MP TA MP FP AP LCF MP MP LCF MP MP TA LCF LCF LCF w SHIFT - TA equals the longitudinal distance shifted

Class Topics Longitudinal Stability Terms Drag / Trim Longitudinal Weight Shifts Example Longitudinal Weight Adds/Removals Examples

DRAG - A design feature having the draft aft greater than the draft fwd. Primarily done to increase plant effectiveness. 16' 0" 14' 0" DWL DRAG = 2 FT By the Stern

TRIM - The difference between the forward and after drafts in excess of drag. DRAG = 0 16' 14' TRIM = 2 FT By the Stern

DRAG = 1 Ft By the Stern 15' 14' TRIM =

DRAG = 1 Ft By the Stern 13' 14' TRIM = 2' By the Bow

DRAG = 1 Ft By the Stern 17' 13' TRIM = 3' By the Stern

Class Topics Longitudinal Stability Terms Drag / Trim Longitudinal Weight Shifts Example Longitudinal Weight Adds/Removals Examples

Trimming Moment = w x TA w Change in Trim(CT) = TM MT1" LCF MP FP AP

CT Trimming Moment = w x TA Change in Trim(CT) = TM MT1" LCF MP FP AP

AP FP MP LCF

AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF

AP FP MP LCF CT

AP MP FP CT CT CT CT CT LCF

AP FP MP LCF CT df da

df da CT = + AP FP MP LCF LCF da df CT LCF da df CT LCF da df CT LCF

AP FP MP LCF CT = da df + LCF df LBP/2 LBP/2 + LCF LBP

AP FP MP LCF CT LBP

df df df LBP/2 + LCF df LBP/2 + LCF df LBP/2 + LCF CT df LBP/2 + LCF CT CT LBP/2 + LCF df CT CT LBP/2 + LCF df CT CT LBP/2 + LCF df LBP CT LBP LBP CT LBP/2 + LCF LBP df LBP CT LBP LBP/2 + LCF = LBP LBP LBP/2 + LCF LBP

da df da df df = (LBP/2 + LCF) LBP x CT + CT = = CT - df CT df CT = =

Class Topics Longitudinal Stability Terms Drag / Trim Longitudinal Weight Shifts Example Longitudinal Weight Adds/Removals Examples

Class Topics Longitudinal Stability Terms Drag / Trim Longitudinal Weight Shifts Example Longitudinal Weight Adds/Removals Examples

LCF

LCF

w PARALLEL SINKAGE = TPI Parallel Sinkage (PS) is the distance that the drafts fore and aft increase due to a weight addition. LCF LCF LCF LCF LCF

w PARALLEL SINKAGE = TPI w - PARALLEL RISE = TPI Parallel Sinkage (PS) is the distance that the drafts fore and aft increase due to a weight addition. Parallel Rise (PR) is the distance that the drafts fore and aft decrease due to a weight removal. w TPI - PARALLEL RISE =

Any weight addition can be equated to an addition at LCF and a shift to its final location. AP FP MP LCF

Any weight addition can be equated to an addition at LCF and a shift to its final location. For a weight addition the Trimming Arm (TA) is equal to the distance from LCF to the center of the weight AP FP MP LCF TA

AP FP MP LCF

AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF

AP FP MP LCF TA

AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF AP FP MP LCF

TOTAL DRAFT = PS/PR + df or a AP FP MP LCF df PS da

Class Topics Longitudinal Stability Terms Drag / Trim Longitudinal Weight Shifts Example Longitudinal Weight Adds/Removals Examples

LBP = 500 FT COMPT # 3-100-0-L B = 24 FT L = 30 FT H = 12 FT LCF = 30 FT aft of MP FLOODED TO A DEPTH OF 6 FT AP MP FP 100 LCF 30' 130 280 500 250

WTsw = B x L x D 35 = 123.4 T B = 24 FT L = 30 FT D = 6 FT Wo = 4500 T Wf = 4623.4 T MP AP FP 500 250 LCF 280 100 130

TPI = 40 T/IN PS = w TPI = 123.4 T 40 T/IN = 3.09 IN MP AP FP 500 250 LCF 280 100 130 AP MP FP LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 LCF 280 100 130 500 250

TA = 280 - 115 = 165 FT TM = 165 FT x 123.4 T = 20361 FT-T LCF 280 100 130 MP AP FP 500 250 TA 115

TA = 280 - 115 = 165 FT TM = 165 FT x 123.4 T = 20361 FT-T LCF 280 MP AP FP 500 250 LCF 280 MP AP FP 500 250 LCF 280 MP AP FP 500 250 LCF 280 MP AP FP 500 250 LCF 280 MP AP FP 500 250 LCF 280 MP AP FP 500 250 LCF 280 MP AP FP 500 250 LCF 280 MP AP FP 500 250

CT MT1" = 1050 FT-T/IN CT = TM MT1" = 20361 FT-T = 19.39 IN LCF 280 MP AP FP 500 250 CT

df = (LBP/2 + LCF) x CT LBP = (250 + 30) x 19.39 500 = 10.86 IN LCF 280 MP AP FP 500 250 df

df da = CT - = 19.39 - 10.86 = 8.53 IN - DRAFTf = PS + df = 10.86 + 3.09 = 13.95 IN LCF 280 MP AP FP 500 250 da DRAFTf PS df

DRAFTa = PS + da = 3.09 - 8.53 = -5.44 IN LCF 280 MP AP FP 500 250 DRAFTa da PS DRAFTf PS df