Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Accuracy of 19th century navigators
    From: Geoffrey Kolbe
    Date: 2016 Nov 10, 20:41 +0000
    Just how good were the deep ocean navigators-of-old in maintaining a good knowledge of their position at sea? They did not have an absolute reference, such as a GPS receiver, to check on their workings and sightings as we do, so it is difficult to know just how well 19th century deep sea mariners knew their actual position.

    A novel way of answering this question suggests itself in a paper "Spatial and Seasonal Distribution of American Whaling in the Age of Sail" by Tim Smith et al. They used data culled from whaling logbooks to determine where in the oceans the various whale species could be found. However, they also noted that they found 32 examples where the logs of two ships each recorded a sighting of other, and gave the position. The mean absolute difference  between pairs of reported positions was 0.22 degrees of latitude (with an SD of 0.315 degrees) and 0.54 degrees in longitude (with an SD of 0.667 degrees)

    Naively, we could suppose that on average, the actual position was midway between the recorded positions in each pair and so the average errors in longitude and latitude were in fact half the figures given above - that is about 6.6 minutes in latitude and about 16.2 minutes in longitude.


    ​Geoffrey Kolb​e

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site