Maritime Search Planning Part Objectives • 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 Worksheet 1: Maritime Planning INCIDENT Demonstration Search target (description): Liferaft – no ballast, no canopy, no drogue LKP (lat/long): 17 00 N 110 00 E @ Time (UTC): 041100 UTC Hours of drift (a): 36 Hours Search Time 052300 UTC Worksheet SEA CURRENT Sea / tidal current/knots: 200 Sea Current vector/distance: 200 O O (T) 1.5 (T) knots 1.5 x 36 (a)hrs = knots 54 nm Sea Current vector/distance 200 O (T) at 1.5 knots x 36 (a)hrs = 54 nm Worksheet SURFACE WIND and CALCULATION OF WIND CURRENT Surface winds/knots 045 O (T) 10 knots Reciprocal of Surface Winds/Knots (b) 225 O 10 knots Wind current vector: (use reciprocal bearing and divergence (Figure I-1) 36 (a) hours x 0.35 (T) Wind Current Divergence = Reciprocal Surface Wind + 30o for LKP greater than 10o North Latitude + 30o T = knots (Figure I-1) = 255 O (T) 255 O (T) 12.6 nm 10 knots Wind Current • The effect of sustained local winds on the water’s surface • Takes effect after – 12 hours in a constant direction • Near the coast – consider omitting wind current • Offshore – consider omitting wind current if the area has consistent winds • Appendix N: Figure N-1: Local Wind Current Graph and Table Vol N-1 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 SURFACE WIND and CALCULATION OF WIND CURRENT Surface winds/knots 045 O (T) 10 knots Reciprocal of Surface Winds/Knots (b) 225 O 10 knots Wind current vector: (use reciprocal bearing and divergence (Figure I-1) 36 (a) hours x 0.35 (T) Wind Current Divergence = Reciprocal Surface Wind + 30o for LKP greater than 10o North Latitude + 30o T = knots (Figure I-1) = 255 255 O (T) 12.6 O (T) nm 10 knots Calculation of Drift Error (De) • De = [de (L) + de (R) + Distance L/R] ÷ • De = [11.25 + 10.68 + 22.8] ÷ • De = 22.36 de (L):(12.5 to 33% of Distance L) 11.25 nm de (R):(12.5 to 33% of Distance R) 10.68 nm Datum • A datum point is established at the mid-point between the ends of the leeway vectors • De is the radius of the circle of probability around the datum De Datum Leeway Total Water Current Point Actual T arget Dr ift LKP Worksheet 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 Worksheet TOTAL ERROR (E) Total probable error (E): E= √(De2+ x2 + y2) E = √ 497.29 + 225 + 0.01 = √ 722.3 = 26.8 E = √ De2 + X2 + Y2 E = √ 22.32 + 152 + 0.12 E = √ 497.29 + 225 + 0.01 E = √ 722.3 E = 26.8 Total Probable Error (E) E is the radius from the datum Datum 50% chance of target being inside the circle Leeway Divergence LKP Worksheet SEARCH AREA Safety factor (circle) (fs) 1.1 1.6 Search radius (E x fs) 29.48 nm Search radius rounded up to whole figure: 30 nm Search area: 3600 nm2 2.0 2.3 2.5 Safety Factor • Multiply the established total probable error (E) by the Safety Factor; • 1.1 Initial Probability Area (1st Search) • 1.6 Second Search • 2.0 Third Search • 2.3 Fourth Search • 2.5 Fifth Search Probability Area Total Probable Error = E Then Multiply E By Safety Factor 1.1 (1 st Search) Search radius rounded up to whole figure: 30 nm Search Area BOX = Search Area Leeway Total Water Current LKP Search area: 3600 nm2 Maritime Search Planning End of Part [...]... 497 .29 + 22 5 + 0. 01 = √ 722 .3 = 26 .8 E = √ De2 + X2 + Y2 E = √ 22 . 32 + 1 52 + 0. 12 E = √ 497 .29 + 22 5 + 0. 01 E = √ 722 .3 E = 26 .8 Total Probable Error (E) E is the radius from the datum Datum 50% chance of target being inside the circle Leeway Divergence LKP Worksheet 1 SEARCH AREA Safety factor (circle) (fs) 1. 1 1. 6 Search radius (E x fs) 29 .48 nm Search radius rounded up to whole figure: 30 nm Search. .. area: 3600 nm2 2. 0 2. 3 2. 5 Safety Factor • Multiply the established total probable error (E) by the Safety Factor; • 1. 1 Initial Probability Area (1st Search) • 1. 6 Second Search • 2. 0 Third Search • 2. 3 Fourth Search • 2. 5 Fifth Search Probability Area Total Probable Error = E Then Multiply E By Safety Factor 1. 1 (1 st Search) Search radius rounded up to whole figure: 30 nm Search Area BOX = Search Area... W (L) - 24 = 20 1 o (T) Leeway speed 0.78 x (a) 36 hrs = 28 .08 nm Leeway vector: (LW) Leeway distance: L W (R) + 24 = 24 9 o (T) Leeway speed 0.78 x (a) 36 hrs = 28 .08 nm Worksheet 1 DRIFT ERROR Distance (L) 90 de (L):( 12 . 5 to 33% of Distance L) Distance Left/Right = 22 .8 nm 11 .25 nm Distance (R) nm De = [de (L) + de (R) + Distance L/R] / 2 85.5 de (R):( 12 . 5 to 33% of Distance R) De = 22 .36 10 .68 nm... on chart • de (L) and de (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) • De = [de (L) + de (R) + Distance L/R] ÷ 2 • De = [11 .25 + 10 .68 + 22 .8] ÷ 2 • De = 22 .36 de (L):( 12 . 5 to 33% of Distance L) 11 .25 nm de (R):( 12 . 5 to 33% of Distance R) 10 .68 nm Datum • A datum point is established...Worksheet 1 TARGET LEEWAY Leeway Angles (divergence) (Table I .1 or I .2) : Reciprocal Surface Wind (b) Leeway vector: (LW) L W (L) - 24 = Leeway speed: (knots) = (Multiplier x Wind Speed) ± Modifier (Table I .1 or I .2) [ 0.057 Leeway distance: (Leeway speed 0.78 20 1 o Multiplier x 10 x (a) 22 5 o (T) ± (T) 24 L W (R) + 24 = Wind Speed = 0.57 ] ± 0 . 21 36 hrs = 28 .08 nm o (T) 24 9 Modifier= 0.78... 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 Worksheet 1 TOTAL ERROR (E) Total probable error (E): E= √(De2+ x2 + y2) E =... Probable Error = E Then Multiply E By Safety Factor 1. 1 (1 st Search) Search radius rounded up to whole figure: 30 nm Search Area BOX = Search Area Leeway Total Water Current LKP Search area: 3600 nm2 Maritime Search Planning End of Part 2