sounding line/intervals of fathoms

[navi tasan]

This is the definition of 'sounding line' from the American Heritage Dictionary.


sounding line

NOUN:
A line marked at intervals of fathoms and weighted at one end, used to determine the depth of water. Also called lead line[FONT=arial,sans-serif][SIZE=-1].[/SIZE][/FONT]

source:
Definitions of sounding line - OneLook Dictionary Search

Is the line marked at intervals of a fathom or at intervals of fathoms?

I suppose there are marks on the line and the distance between every two consecutive lines is one fathom.
Maybe I haven't got the meaning correctly.

Gratefully,
Navi.

 

[JMurray]

not a teacher

According to Wikipedia, the old sounding lines were marked "at every second or third fathom, in a traditional order: at 2, 3, 5, 7, 10, 13, 15, 17, and 20 fathoms". I believe that modern sounding lines are marked in a variety of ways including single units of a fathom, metre, or whatever measure is being used.

 

[navi tasan]

Aaah!
Thank you very much JMurray!

I sort of get it. Although 'at every second or third fathom' does sound a bit arbitrary and the jump from 2 to 3 is a bit of a mystery to me.

Gratefully.
Navi.

 

[JMurray]

not a teacher

This link has some interesting information on the sounding lines used by 19th century US steamboat pilots, and their connection to the writer Mark Twain.
What do Mark Twain and your depth sounder have in common? - BoatSafe.com