CELESTIAL NAVIGATION Section 22 Day’s Work at Sea Prepared by: John C. Hudson Saanich Peninsula Squadron, VISD Jan 2006 / Rev. Jan 2007

Day’s Work at Sea - uses most of navigational procedures learnt in this course - real world weather conditions often preclude sights being taken at normal times - regardless, navigator must maintain DR course at all times and EP’s when prudent

Responsibility of a Navigator - navigator required to know vessel’s position as accurately as possible at all times to ensure safety of vessel, passengers, crew and cargo - no universally accepted standards of navigation at sea; each navigator must develop a daily procedure

Responsibility of a Navigator daily procedure will depend on: - particular vessel - its location - prevailing weather - navigational equipment avail. - orders from captain/owner

Responsibility of a Navigator - recommended that navigator takes daily dawn and twilight star FIX as well as noon RFIX - supplement during day by sun and/ or moon sights as needed - if so equipped, navigator should obtain ship’s position by electronic means

Responsibility of a Navigator - for twilight FIXes, 3 body fix is desirable - run of 3 observations on each of 3 bodies, averaging times and “hs” is good practice to improve accuracy and eliminate bad sights - advanced planning and pre- calculation of expected positions is sign of efficient navigator

Navigator’s Notebook and Log - navigator expected to record and retain all data to substantiate plotted positions recorded in log and on chart - these records should be readily available for submission to authorities in event of an enquiry

Navigator’s Notebook and Log - no specified method of maintaining such data; record may be simply in form of continuous chronological account of: - navigational procedures followed - calculations made - positions determined

Navigator’s Notebook and Log another format may use separate records for: - course, speed, times and positions of course changes and celestial observations - log of position co-ordinates together with method of determination

Navigator’s Notebook and Log - example of deck log used in CPS courses See figure on page deck log should contain complete account of voyage and is important reference document

Data to be submitted to Class Instructor - successful completion of Day’s Work at Sea is pre-requisite of CN course - class instructor must certify that this requirement has been completed - submission to include Plotting Sheet, Sight Reduction sheets, Work sheets showing all calculations and Deck Log

Data to be submitted to Class Instructor - all work should be arranged in chronological order - for Deck Log, use blank DL01 forms - remarks column should contain concise information relevant to navigational work (see Fig 16.12, page 137)

Data to be submitted to Class Instructor - courses, lines of position, FIXes, etc. should be plotted and labelled according to CPS standards as shown in section 16 - do not obscure lines with labels or other recordings - submit calculations separately on work sheets

Numerical Tolerances - report zone time to nearest minute - watch time to nearest second - position to nearest 0.1 minute - azimuth to nearest 0.1 degree - set of current to nearest degree - drift of current to nearest 0.1 knot - Great Circle distance to nearest mile

Accuracy Required - answers are given for “Sienne Cruise” on page 172 so work may be checked by student as it progresses - exact duplication of co-ordinate in plotted positions is not expected, but if exceeds 0.1’ in L or Lo, calculation and plot should be checked

Time of Completion of the Day’s Work at Sea - this exercise should be started as soon as relevant sections are covered in class - “Sienne Cruise” is very similar to Open Book portion of CN Course Examination, so important to fully understand and complete correctly - read section carefully!

BEST WISHES for the SIENNE CRUISE and the EXAM The End