Expanding Box Pattern

The Expanding Box covers a large area and is slow – so it is used when there is minimal drift.  The search starts around the DATUM position and works its way outward.

Note : The leg length has to be equal to, or smaller than, the sweep width – this is important otherwise there will be areas that are not being searched.

•A : The DATUM or START position which can come from

otype in your own coordinates (see Coordinate input in the Important information section) - this will be the START position of the search pattern

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 search pattern will start half a leg length to the left of the Datum position, so that the drift line will be in the middle of the search pattern.

•B : Distance from Datum : normally an Expanding Box search is started at the Datum position, and so the default value of zero is fine.  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, the default for the bearing will be that 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 - this is used when calculating the time it will take to complete the pattern

•E : Search Minutes - this information will dictate the length of the search pattern.  SearchWell only calculates the number of legs that can be searched in the given number of minutes (using the RV Speed to calculate the distance covered during the search

•F : The leg distance - this is compulsory for an Expanding Box pattern

•G : Track spacing - this is not used in the Expanding Box pattern

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

•I : Track spacing Info - when you click on this button the Sweep Width table is displayed to guide the track spacing

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

•K : The Expanding Box is the pattern that displays by default as long as there is a leg length, otherwise click on the circle next to the work "Expanding Box" to display the information if it is possible to do so

•L: The details of the pattern

•M : 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)

•N : 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

•O : 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: Easy EPub and documentation editor