Maritime search planning part 2 MILSAR 1 2005

Maritime Search Planning... • Maritime search planning theory and various models Part 1 • Worksheet method of drift planning including a demonstration • Individual exercises using the

Maritime Search Planning

• Maritime search planning theory and

various models (Part 1)

• Worksheet method of drift planning

including a demonstration

• Individual exercises using the worksheet

• Demonstration of Net Water Movement

Worksheet 1

SEA CURRENT

Sea / tidal current/knots: 200 O (T) 1.5 knots

Sea Current vector/distance: 200 O (T) 1.5 knots x 36 (a)hrs = 54 nm

Sea Current vector/distance

200 O (T) at 1.5 knots x 36 (a)hrs = 54 nm

Worksheet 1

SURFACE WIND and CALCULATION OF WIND CURRENT

Surface winds/knots 045 O (T) 10 knots Wind Current Divergence = Reciprocal Surface Wind + 30o for LKP greater than 10o North Latitude

Reciprocal of Surface Winds/Knots (b) 225 O (T) 10 knots + 30o T = 255 O (T) 10 knots

Wind current vector: (use reciprocal bearing

and divergence (Figure I-1) 36 (a) hours x 0.35 knots (Figure I-1) = 255 O (T) 12.6 nm

Wind Current

• The effect of sustained local winds

on the water’s surface

• Takes effect after 6 – 12 hours in a

constant direction

• Near the coast – consider omitting wind current

• Offshore – consider omitting wind current if the

area has consistent winds

Wind current vector: (use reciprocal bearing and divergence (Figure I-1)

36 (a) hours x 0.35 knots (Figure I-1) = 255 O (T) 12.6 nm

Worksheet 1

SURFACE WIND and CALCULATION OF WIND CURRENT

Surface winds/knots 045 O (T) 10 knots Wind Current Divergence = Reciprocal Surface Wind + 30o for LKP greater than 10o North Latitude

Reciprocal of Surface Winds/Knots (b) 225 O (T) 10 knots + 30o T = 255 O (T) 10 knots

Wind current vector: (use reciprocal bearing

and divergence (Figure I-1) 36 (a) hours x 0.35 knots (Figure I-1) = 255 O (T) 12.6 nm

Worksheet 1

TARGET LEEWAY

Leeway Angles (divergence)

(Table I.1 or I.2): Reciprocal Surface Wind (b) 225 o (T) ± 24 o(T)

Leeway vector: (LW) L W (L) - 24 = 201 o (T) L W (R) + 24 = 249 o (T)

Leeway speed: (knots) = (Multiplier x

Wind Speed) ± Modifier

(Table I.1 or I.2) [ 0.057 Multiplier x 10 Wind Speed = 0.57 ] ± 0.21 Modifier= 0.78

Leeway distance: (Leeway speed 0.78 x (a) 36 hrs = 28.08 nm

The movement of an object as it is pushed through the water by wind blowing against its exposed surfaces The pushing force of the wind is countered by drag on the

underwater surface.

As an object drifts its lack of symmetry will cause the object to deflect (or diverge) to either the left or right of the downwind direction.

Wind

D iv

er ge

nc e

Leeway – Craft Types

Leeway vector: (LW) L W (L) - 24 = 201 o (T)

Leeway speed 0.78 x (a) 36 hrs = 28.08 nm Leeway distance:

Leeway vector: (LW) L W (R) + 24 = 249 o (T)

Leeway distance: Leeway speed 0.78 x (a) 36 hrs = 28.08 nm

Worksheet 1

DRIFT ERROR

Distance (L) 90 nm Distance (R) 85.5 nm

de (L):(12.5 to 33% of Distance L) 11.25 nm de (R):(12.5 to 33% of Distance R) 10.68 nmDistance Left/Right = 22.8 nm De = [de (L) + de (R) + Distance L/R] / 2 De = 22.36

Calculation of Drift Error

• Distance (L) and Distance (R) from LKP on chart

• d e (L) and d e (R) is usually 12.5% of the

distance (L) and distance (R) from LKP

SMC may use up to 33%

• Distance Left/Right is obtained from chart

Calculation of Drift Error (De)

• D e = [d e (L) + d e (R) + Distance L/R] ÷ 2

• D e = [11.25 + 10.68 + 22.8] ÷ 2

• D e = 22.36

d e (L):(12.5 to 33% of Distance L) 11.25 nm

d e (R):(12.5 to 33% of Distance R) 10.68 nm

Actual Target Drif

Actual Target Drift

Worksheet 1

FIX ERRORS

Distress craft error (x): (Table J.1, J.2 or J.3) 15 nm

Search craft error (y): (Table J.1, J.2 or J.3) 0.1 nm

Navigational Fix Errors

Appendix N – Probable Errors of Position

• X is the estimated error of the position of the craft in distress

• Y is the estimated error of the position of the search craft

TOTAL ERROR (E)

Total probable error (E): E= √(De2+ x2 + y2) E =  497.29 + 225 + 0.01 =  722.3 = 26.8

Leeway Divergence

Total Probable Error (E)

• Multiply the established total probable error (E) by the Safety Factor;

• 1.1 Initial Probability Area (1 st Search)

• 1.6 Second Search

• 2.0 Third Search

• 2.3 Fourth Search

Safety Factor

Search radius rounded up to whole figure: 30 nm

Leeway Total Water Current

LKP

Search Area

BOX = Search Area

Search area: 3600 nm 2

Maritime Search Planning

End of Part 2