The sinking of MS Estonia: Case Reopened Part VII

Vixen said:
A 'mile' is a wonderful word. 'M-i-l-e'. So evocative and everyone knows exactly how long it is. It knocks the horrid 'kilometre' into a cocked hat.

A 'nautical mile' is merely a very naughty mile and needs to be afforded some latitude!

A knot: now here's yet another wonderful Old English word. Short, sharp and straight to the point. 'Knot'.
Click to expand...
Your risible attempts at humour do not deflect from the point being made, that you do not know what you are talking about.
 
JayUtah said:
Care to guess why ship speed used to be reported in knots and fathoms?
Click to expand...
I came across this in a video recently, knots because ropes with equally space knots released into the water were used for gauging speed and fathoms had something to do with the length of a man's outstretched arms (~6ft)? Something like that.
 
JesseCuster said:
I came across this in a video recently, knots because ropes with equally space knots released into the water were used for gauging speed and fathoms had something to do with the length of a man's outstretched arms (~6ft)? Something like that.
Click to expand...
Yes, if you are using a sounding line and lead you can quickly measure the depth by hauling in the line between outstretched arms to get a quick and usable depth measurement.

A 'proper' sounding line is marked along it's length with distinctive marks so you can read off the fathoms without going through the whole outstretched arms rigmarole.

The lead weighs about seven pounds. One fathom does not need a mark, two fathoms gets two strips of leather, three strips for three fathoms, no mark at four, white cotton at five and red wool at seven, then a piece of leather with a hole in it for ten fathoms or sixty feet total for a 'shallow water lead line'
The sections with no mark are called 'deeps' and are that way because long experience has proven them unnecessary for actual use.

The end of the lead is concave and can be packed with tallow to bring up a sample of the bottom to help with location as Admiralty Charts tell you what the bottom is made of.

When I joined the Navy in 1980 the Manual Of Seamanship Volume Two still had a section on the proper use of the sounding line and lead.

The picture is slightly misleading as the marks are woven through the line so they can't move, not tied or wrapped round it.

1758483512431.png

A ship used to estimate it's speed through the water using a Log Line, that had distance marked off with knots, hence the name for a boats speed through the water.
It was paid out astern for a fixed length of time to get the number of knots.

1758483816413.png
 
Last edited:
JesseCuster said:
I came across this in a video recently, knots because ropes with equally space knots released into the water were used for gauging speed and fathoms had something to do with the length of a man's outstretched arms (~6ft)? Something like that.
Click to expand...
Yeah kinda. You count the equally spaced knots on the streaming line passing through your hand per a 28-second glass. But if you can see the last knot and estimate how many feet (or fathoms or barleycorns) past that last knot you clapped onto the line after 28 seconds, you report that too as a pseudo fraction.

The “knot” is just a particular fixed distance on the measuring line, akin to measuring car speed in tire revolutions. They’re just over 47 feet apart under the rubric of it being one nautical mile per hour. One knot per glass. They’re 48 feet apart under the rubric of a knot being eight fathoms. Hence a fathom was at times an appropriate subdivision of a knot of distance.

How long a fathom is becomes a separate headache. Canonically now it’s six feet. But an important early reference (The Country Justice) gives it as seven feet.
 
Last edited:
For greater depth than 10 fathoms there is a longer line with additional marks, the 15 and 17 are repeats of the shallower marks.

Also note that the use of different materials, leather, cotton, wool and tied knots is to allow the leadsman to feel the marks and know the depth in the dark.

1758484013037.png
 
Last edited:
Vixen said:
Please let me know why you think the figures as stated, above, are out by about a factor of 2! Let's see which one of us is wrong and which one of us has a desperate need to blurt out, 'So much for honesty, integrity and precision'. Perhaps set an example.
Click to expand...
This is utter idiocy on your part
1 knot is 1,852 metres in 3,600 seconds.
 
Andy_Ross said:
Yes, if you are using a sounding line and lead you can quickly measure the depth by hauling in the line between outstretched arms to get a quick and usable depth measurement.
Click to expand...
Historically a sounding line was different than the log line and marked differently. If your sounding corresponded exactly to a knot, you report it as “by the mark.” If you’re estimating between knots using outstretched hands, you report it as “by the deep,” as you note. There’s another qualifier, but I forget what it is. And finally, “No depth with this line” if the weight never hits bottom. The number you report is always in fathoms, either measured or interpolated.

The apparatus at the end of the log line (for speed) featured an ingenious set of vanes to create drag, but which snapped into streamline via a sharp jerk on the line to facilitate reeling it in.
 
Last edited:
JayUtah said:
Historically a sounding line was different than the log line and marked differently. If your sounding corresponded exactly to a knot, you report it as “by the mark.” If you’re estimating between knots using outstretched hands, you report it as “by the deep,” as you note. There’s another qualifier, but I forget what it is. And finally, “No depth with this line” if the weight never hits bottom. The number you report is always in fathoms, either measured or interpolated.

The apparatus at the end of the log line (for speed) featured an ingenious set of vanes to create drag, but which snapped into streamline via a sharp jerk on the line.
Click to expand...
Yes see my posts above
 
Vixen said:
Look, I know I am a numbers person and am flattered that people think I am geekish enough to convert metres per second (the standard SI unit for measuring wind speed) into (a) kilometres per hour, and then (b) miles per hour and then (c) apply a factor of 1.15 to obtain knots, but there is no need to be as mathematically minded as myself to instantly spot that 18 m/s - being decimal-based - is never going to be like for like with miles, being imperial measures based. Yes, historically wind might have been measured by knots but there is no way even the most unmathematical person is gong to think 18 m/s converts so easily into 18 knots. :wackylaugh: However I have been nerdish enough to estimate 18 m/s wind speed would equate to roughly 35 kts, off the top of my head.
Click to expand...
A typically pathetic attempt to cover your incompetence.
 
Vixen said:
SOLAS documents are in pdf, which isn't good etiquette for people who don't want to download pdf, and the SOLAS documents are quite longwinded and densely worded. You can download SOLAS V22 by simply doing a quick google search if you want to look it up for yourself.
Click to expand...
Garbage.
 
Though I don't know how to use it or where it currently is in the house, I have an antique slide rule, made if I recall correctly by the Albert Nestler company. It's a memento of my very late grandfather. I do recall that when I had to buy a scientific calculator for college, it seemed damnably expensive.
 
You must log in or register to reply here.

Back
Top Bottom