Topic: logbook conventions
posted July 17, 2008 04:54 PM
in both our inland and coastal course and in the cel nav course we use sample logbooks without clarifying a basic point as to what recisely to the entries mean. we will make some notes like below in the next issue.
a typical entry might have
time = T
position (by some means)
The time and log are labeling everything in the entry in this sense: the
log is the value of the log at time T. it is accumulated mile, like an odometer. some vessels have two. One is ongoing permanent, all miles of the vessel, the other is a trip log.
Course is the course you either changed to or continued on with at time T
Speed is the speed you have at time T
and position is the position at time T.
If speed and course are swinging around a bit, then we need to think of what is the might average at this moment and not just read the dials and write it down.
Speed should be knotmeter speed. in another location it would be good to record SOG
Course should be compass course steered. in another column you might record COG
the position would these days typically be from the GPS, but if you do not have GPS then it could be any type of fix or it could be a DR position. the main point is to get some actual lat lon into the log book once a watch or so.
Note this special entry when sailing offshore. that is one called "taking your departure." A departure is your last visual contact with land. Take bearing to it, and estimate its distance off (or read it from radar), and record this as the landmark slips out of sight over the horizon.
------ thanks to Dennis W for pointing this out
Sometimes we overlook the most basic things.... note that sometimes people when filling the logbook will use some sort of average over the last watch for the speed and course, thinking this is better.
... in other words, it is a perfectly good question here as to what is right procedures. Average values may seem right but it is not.
If your actual course and speed over the last watch was different than the last log entry, then you should have made a new log entry when the course or speed changed. The best working convention is the course and speed are what you had at the time listed, and if this changes, make a new entry.
From: Starpath, Seattle, WA