NauticEd Sailing Education - Learn to Sail and get Sailing Certifications

Student
Conan Hom
Lexington, MA, USA
More User info Crew Level 0
Status: Sailor
Qualified days: 8

Deriving true heading from ships compass

Posted 2018, Apr 23 03:14

If deviation is a function of the magnetic heading heading then if we know the true heading we can calculate the ships compass (true + variation +deviation). However if we have the ships compass reading and we know the variation but we wish to have the true heading, is it possible to find the true heading? I'm not so sure because we won't know the deviation (since we don't know the magnetic heading which is necessary to calculate the deviation). Is this a correct assessment?

Add reply

0 0

Replies

Administrator
Grant Headifen

Reply 2018, Apr 23 14:59

To go from ships compass to magnetic heading you need to know the deviation. This is from a table associated to the individual ship.

0 0

Student
Conan Hom
Lexington, MA, USA
More User info Crew Level 0
Status: Sailor
Qualified days: 8

Reply 2018, Apr 23 22:16

Hi Grant, That's the issue: if we only have the ships compass to start with, then we can't get the deviation? So in practice what do people do if they only have the ships compass to get the magnetic and true headings if the deviation cannot be determined?

0 0

Administrator
Grant Headifen

Reply 2018, Apr 23 22:20

Deviation is never determined - is comes from a table supplied with the ship. Typically it is small. And can be checked with a handheld compass which is not subject to the metalic objects close by. I reality you will never really get this accurate to warrant it's use.

0 0

1 - 3 of 3 replys

Add reply

* - required fields

User

Please signin first

Message *

Add your reply in a positive and constructive manner and tone. Be as specific and clear as possible. Other students will vote your reply up or down depending on its usefulness the clarity. Your comments are always editable.