ZigZag Pattern

This pattern is used when there is no clear idea of where the casualty is.  It allows every place in the search pattern area to be observed twice and from different sides.

•A : The Datum or Start position which can come from

otype in your own coordinates (see Coordinate input in the Important information section) - these coordinates give the position the search pattern will start

opreviously calculated Datum positions - when you click on the circle to the left of "Calculated Coordinate" a list of the last calculated Datum positions is displayed and you can select the one you need by clicking on it.  In this case the LKP position related to the Datum is displayed.  The Datum position and the drift path will be in the middle of the legs of the pattern.

•B : Distance from Datum : normally a ZigZag search is started up-drift of the Datum position, and so the default value of zero needs to be changed to a negative number.  If you want to

ostart closer to the LKP position (up-drift) then enter a negative number of nautical miles

ostart down-drift of the Datum position then enter a positive number of nautical miles

•C : The drift bearing which will guide the bearing of the pattern. 

oIf you entered your own Start Coordinates, you must enter your own bearing.  

oIf you selected a previously calculated Datum position then the drift bearing from that calculation will be displayed

•D : The speed the rescue vessel will average during the pattern execution

•E : Search Minutes - the default is 60 minutes but this can be changed as required.  It is used in combination with the RV Speed to calculate how many legs can be executed in the Search time

•F : Leg distance - this is compulsory for a ZigZag Pattern

•G : Track spacing - this is compulsory for a ZigZag Pattern

•H : Arc Angle - this is not used in the ZigZag pattern

•I : clicking on this "Calculate" button will calculate the search patterns using the information in the header

•J : Prompt for Distance from Datum - most ZigZag patterns start up-drift (closer to the LKP) of the Datum Position, and if the value in the Distance from Datum is zero,  SearchWell offers to place the Datum position in the middle of the pattern.  If you click on the 

oYes button, it will calculate the start position of the pattern so that the Datum position will be in the middle of the pattern .... it will be a negative number

oNo button, the "Distance to Datum" will remain at zero and the pattern will start in line with the Datum position

You can start the pattern any distance from the Datum position if you want to - 

oto start closer to the LKP position (up-drift) then enter a negative number of nautical miles

oto start down-drift of the Datum position then enter a positive number of nautical miles

•A : The distance from Datum has automatically been changed if you click on the "Yes" button described above.  Then you must click on the Calculate button again so that the patterns are recalculated with the new information.

•B : Click on the calculate button

•C : select the ZigZag pattern

•D : the details of each leg of the pattern

oUse - this column contains "y" by default and it means that the leg will be included in the GPX file that is created and sent to the vessel (see Multi-vessel searches)

oLeg - the leg number

oDist - the distance of the leg in nm

oBear - the bearing of the leg from leg start point to leg end point

oMins - the number of minutes the leg will take to complete given the rescue vessel speed

oTot Mins - the total number to minutes that will have been used to get to the end point of the leg

oDD Coords - the coordinates of the turning point in Decimal Degrees

oDDM Coords - the coordinate of the turning point in Degrees and Decimal Minutes

•E :  Use All - clicking on this will change the value in the "Use" column.  The default is that all the values in this column = "y", and if the "Use All" check box is clicked and the "y" values will be replaced with blank values.  If the values are currently blank, they will be replaced with "y" when the check box is clicked. (for more details see Multi-vessel searches)

•F : Total Stats : this section shows the total statistics for the entire calculated pattern

oThe number of minutes it will take for the entire pattern to be executed given the average speed of the vessel

oThe time it will take in hours and minutes

oThe distance traveled for the entire pattern

oThe area covered by the search pattern

•G : Click on this GPX button to create a GPX file that will include the selected legs of the pattern 

Created with the Personal Edition of HelpNDoc: Maximize Your Productivity with HelpNDoc's CHM Help File Creation Features