Section 5

Plotting Basics

5.4

The Logbook

Navigators keep track of a lot of things during a cruise: courses, bearings, changes in speed, estimated effects of current and leeway, weather, and fuel usage to name a few. A logbook or log is used to enter information for later referral.

Logbooks may vary from notepads to elaborately-bound books with custom-printed pages. Regardless of type, they should permit quick and orderly entries in an easy-to-read format. Legibility ensures that other crew can follow the boat's track and conditions encountered. Commercial vessels are required to keep a log. In the case of an incident, logs may provide evidence in court.

There are no hard and fast rules about what goes into a log. Some boaters restrict entries to navigational matters. Certainly anything to do with any urgency — monitoring a distant "Mayday" call, for example — should be entered in detail. Others use it as more of a journal as well as a log with light-hearted entries such as "We saw seven porpoises today", or "Running low on peanut butter". Entries should allow the passage to be re-traced and events to be re-constructed.

Pages are usually divided into columns under headings for time, course, speed, and distance traveled. A wider column provides a place for remarks, including weather observations. Pre-formatted logbooks are available at marine supply stores but many boaters prefer to make their own.

What to Include

The logbook provides a record of a journey that can be revisited for facts or fond memories. Here are suggestions as to what should be included:

points of departure, course, speed, distance to DR positions, fixes
bearings, lines of position, buoys used as fixes
courses and headings, changes of course
time of day (24-hour clock)
effects of leeway and current
changes in local variation
weather, changes in weather if deteriorating
engine operation, maintenance, and problems

When doing the cruising exercises in this course, you may want to enter information in a log before plotting. This can help you organize the material and avoid mistakes.

Logbook Page
A blank logbook page that can be printed and copied.
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