Navy back to Sextant

SmithDoor · Nov 16, 2024

ChazzC said:
When I was starting on my MBA I checked about skipping the math courses: they asked if I used Calculus in my day-to-day work and weren’t amused when I told them, “Nobody uses Calculus in their work.” Other than a waste of time and money (was reimbursed), the Statistics & Matrix Math courses were a nice refresher (no Calculus).

I agree 99% never use Calculus after college

I use Math up to Calculus a lot when working doing engineering.

But I think in reality only about 99% never use Calculus after college.
Most just wast of time.
I have ask license Engineers that question and all said same thing only used algebra.
It is not some ever need.

What did I could not go and buy off the shelf. For my work there no charts or tables for parts
So I had figured out what was need then make the part.
Some parts took up to 5 pages for others to read.
I forgot how many pages a job would have.
----------------------------------------
I have look at some jobs that my competitors use through and pray engineering. They heavy plate then why.
----------------------------------------
I found in different industry the engineer said they extra heavy to keep the cost of license engineering cost down. Basically he did could not do any engineering but on he had a degree from a college for engineering.
----------------------------------------
I never do a job without doing all the engineering first. It one best butt covers any can do.

Dave

SmithDoor · Nov 16, 2024

ChazzC said:
Large ships use multiple shafts to get the necessary Hp into the water, also for redundancy. Smaller and auxiliary ships typically have one.

Yes, with multiple shafts you can “steer” a ship without using the rudder, but it is not practical for anything other than limping around.

I was to see supper size with screw.
I am say all but I seen just one

Dave

ChazzC · Nov 16, 2024

SmithDoor said:
I was to see supper size with screw.
I am say all but I seen just one

Dave

Cargo ships, like the Dali that struck the Key Bridge, typically have one screw: don’t need quick response or high speeds, just go in straight lines. The Dali displaces 149,000 t, is 984’ long and has 55,630 Hp. In comparison, the USS George H. W. Bush (CVN77) displaces 114,000 t, is 1,040’ long (waterline) and has 260,000 Hp.

SmithDoor · Nov 16, 2024

ChazzC said:
Cargo ships, like the Dali that struck the Key Bridge, typically have one screw: don’t need quick response or high speeds, just go in straight lines. The Dali displaces 149,000 t, is 984’ long and has 55,630 Hp. In comparison, the USS George H. W. Bush (CVN77) displaces 114,000 t, is 1,040’ long (waterline) and has 260,000 Hp.

CVN has has 65,000 hp per screw.
War ship always have lot more hours power .
The cargo ships are built for fuel economy.

I do not know why on a cargo they only have one screw.

I wonder on a cargo ship if have Sextant for Navigation.
The sextant is a safety equipment if some happens to all other Navigation equipment.

In October when read the article the Navy stop using sextant. Someone very good can find there location in less that mile .

Dave

Nikhil Bhale · Sunday at 3:00 AM

Hi,
I work in merchant navy as engineer. We have sextant onboard. We have gyro compass and magnetic compass onboard too. It is duty of navigating officer to take noon sight everyday at noon to calculate for position. We also have GPS subscription for accurate position keeping.
Ships generally have a 2 stroke main engine which is really big. You can fit only one in most of the ships. Now there are some ships with 2 propellers driven by electric motors or smaller 4 stroke engines.
Some ships don't even have rudder, they have steerable propeller.

Regards
Nikhil

GreenTwin · Sunday at 4:23 AM

I hear a lot of folks say "I never used calculus after college", but if you work as an engineer, then you use the knowledge constantly.

Its like saying "I learned to read in school, but I have never written a book, and so I don't use that skill".
But then you become a chef, and read a book that contains 10,000 recipes.

You most certainly use calculus as an engineer; it is the key to understanding everything you do, and the key that gives you entrance into a huge universe of knowledge that few even know exists.
There is no engineering without calculus, whether you sit around and solve forumulas or not.

People make calculus out to be some sort of black-art/vodoo type magical thing, but it is in many respects just summing area under a curve (integration), or calculating the slope of a tangent point on a curve (differentials).
Calculus is a lot like 3D modeling; very confusing at first, and then one day it all clicks, and you can see the "big picture" of what it is all about, and it becomes a lot easier than you imagined.
.

SmithDoor · Sunday at 2:17 PM

Nikhil Bhale said:
Hi,
I work in merchant navy as engineer. We have sextant onboard. We have gyro compass and magnetic compass onboard too. It is duty of navigating officer to take noon sight everyday at noon to calculate for position. We also have GPS subscription for accurate position keeping.
Ships generally have a 2 stroke main engine which is really big. You can fit only one in most of the ships. Now there are some ships with 2 propellers driven by electric motors or smaller 4 stroke engines.
Some ships don't even have rudder, they have steerable propeller.

Regards
Nikhil

Gyro compass and magnetic compass onboard sounds like aircraft.
Glad to here they a sextant.
I can see why calculators are noon. I guess it was taking noon for your location on the sea.

Any photos?
How does the steering propeller work?

Dave

GreenTwin said:
I hear a lot of folks say "I never used calculus after college", but if you work as an engineer, then you use the knowledge constantly.

Its like saying "I learned to read in school, but I have never written a book, and so I don't use that skill".
But then you become a chef, and read a book that contains 10,000 recipes.

You most certainly use calculus as an engineer; it is the key to understanding everything you do, and the key that gives you entrance into a huge universe of knowledge that few even know exists.
There is no engineering without calculus, whether you sit around and solve forumulas or not.

People make calculus out to be some sort of black-art/vodoo type magical thing, but it is in many respects just summing area under a curve (integration), or calculating the slope of a tangent point on a curve (differentials).
Calculus is a lot like 3D modeling; very confusing at first, and then one day it all clicks, and you can see the "big picture" of what it is all about, and it becomes a lot easier than you imagined.
.

I did use Calculus for my work.
TO many license engineers relied on forums ONLY.
Most engineers in the construction in industry avoid it.

I there so types of engineer that use Calculus.

It is very hand for manufacturing. My brother also use Calculus for his line work he does want me give what he did.
My son took Calculus too he just can see how any one ever use Calculus. I show to him but did get it.

Dave

SmithDoor · Sunday at 2:28 PM

Just think of navigating on the open ocean and making maps for others to use in the 1500's just the equipment list below .Global and maps not shown

How you feel traveling ocean with just this equipment ? .

All this we can build in our shop with the engine for ship too.

Compass

Compass for steel ships aka Binnacle. Patented 1854, by John Gray This is also in aircraft, better Compass in cars,trucks and cellphones. In very small.

Speed and odometer
Knots rope sandglass set at 1/2 hour. Simple use drop rope with triangle so does not move water. Flip sandglass over and cout the knots.
The replacement is Speedometer was Invented 1888 but the tachometer was described in 1810 . {If you add a pro/screw on tachometer you have a measuring speed in water} witch is very close the Speedometer. So some of data dates maybe in error

Astrolabe per Sextant

Just think of sailing 1500's

Dave

SmithDoor · Sunday at 6:26 PM

GreenTwin said:
I hear a lot of folks say "I never used calculus after college", but if you work as an engineer, then you use the knowledge constantly.

Its like saying "I learned to read in school, but I have never written a book, and so I don't use that skill".
But then you become a chef, and read a book that contains 10,000 recipes.

You most certainly use calculus as an engineer; it is the key to understanding everything you do, and the key that gives you entrance into a huge universe of knowledge that few even know exists.
There is no engineering without calculus, whether you sit around and solve forumulas or not.

People make calculus out to be some sort of black-art/vodoo type magical thing, but it is in many respects just summing area under a curve (integration), or calculating the slope of a tangent point on a curve (differentials).
Calculus is a lot like 3D modeling; very confusing at first, and then one day it all clicks, and you can see the "big picture" of what it is all about, and it becomes a lot easier than you imagined.
.

It could be it not used more is most time it takes a lot time to do one calculation. Then they look for a formula that more or less fits to make easier. In some industries that OK.

Today I like Excel. Some things I used basic and program. Both are great for tables. I just think ok the old days where I used paper and slide rule. Still have slide rule just incase it is need. I enjoy the electronic calculator. My First computer was a HP65. The IBM PC in 1981 was Fantastic with printer all my calculations.

Dave

FYI
Before that I replace the hot water heater and the day before goto the hospital I installed a new antenna on roof.
I have not told any here 2 weeks ago I was in the emergency with 103.1° temperature. I had blood infection. Most that would be no big deal. Most would be no big deal.
But in 2009 I was diagnosed with stage 4 colan cancer I was told to go the emergency over 100.5°. I want to diet to live longer so, had few of all green diet. So ask oncologist how long do people live with my diagnose she said no makes pass 10 years.
I did ask two doctors and said samething, I also ask American Cancer twice they said ther stop hearing after 9 years.
Now it is over 15 years hard for me real know how to feel or how to plan anything.

I post the diet om America Cancer
Please post I hope helps others

https://csn.cancer.org/discussion/327889/what-to-eat-to-live-longer#latest

Steamchick · Monday at 3:57 AM

Lots of wisdom here...
Thanks Green Door, until I read your posts I was one who spent 45 years as an Engineer without "using the Calculus", but you simply explained I was using it all the time anyway. - Even today I have written "V ~ dB/dt" without thinking "I am using the Calculus"...
A fascinating thread.
On Navigation:
It reminded me of my Grandfather, - during early days of WW2 - a submarine stopped his ship with gunfire and told the Officers to get the crew into "the boats" and set them off to sail "west to S. America" - 1600miles away.
The Officers were supposed to get on the Submarine, but almost all were killed by the gunfire on the bridge.
The Captain (asleep in his day cabin when the shells hit the bridge - so shocked, but not wounded) was rescued by his steward and hidden on a lifeboat. My Grandfather, Chief Engineer, dressed in only a boiler suit as he had been doing a job somewhere, got to a lifeboat and wasn't identified as an officer when the Germans searched...
So he took charge when the 3 lifeboats were released by the Germans (Captain was suffering from the blast next to his day-cabin), and they sailed 1600 miles to S. America as a group - using a sextant (even Engineer officers had to learn how to use them!), compass and the life-boat chart (S. Atlantic on a single sheet!). It's what people do in wartime... A bit of trigonometry to pass the time?
K2

SmithDoor · Monday at 4:32 AM

Steamchick said:
Lots of wisdom here...
Thanks Green Door, until I read your posts I was one who spent 45 years as an Engineer without "using the Calculus", but you simply explained I was using it all the time anyway. - Even today I have written "V ~ dB/dt" without thinking "I am using the Calculus"...
A fascinating thread.
On Navigation:
It reminded me of my Grandfather, - during early days of WW2 - a submarine stopped his ship with gunfire and told the Officers to get the crew into "the boats" and set them off to sail "west to S. America" - 1600miles away.
The Officers were supposed to get on the Submarine, but almost all were killed by the gunfire on the bridge.
The Captain (asleep in his day cabin when the shells hit the bridge - so shocked, but not wounded) was rescued by his steward and hidden on a lifeboat. My Grandfather, Chief Engineer, dressed in only a boiler suit as he had been doing a job somewhere, got to a lifeboat and wasn't identified as an officer when the Germans searched...
So he took charge when the 3 lifeboats were released by the Germans (Captain was suffering from the blast next to his day-cabin), and they sailed 1600 miles to S. America as a group - using a sextant (even Engineer officers had to learn how to use them!), compass and the life-boat chart (S. Atlantic on a single sheet!). It's what people do in wartime... A bit of trigonometry to pass the time?
K2

I have ask of license Engineers if ever used Calculus and they all had same answer never used Calculus.Thank God for not needing Calculus
It is just a mistrey of life.

******************
On the lighter side I made to 70 today.

Dave

Tug40 · Monday at 9:45 AM

Happy Birthday!
and, life is more mysterious to me every day.

SmithDoor · Monday at 1:39 PM

Tug40 said:
Happy Birthday!
and, life is more mysterious to me every day.

Thank you

Dave

SmithDoor · Tuesday at 12:48 AM

Both sextant and transit advertised accurate
degree is 69.4 miles
One minute is 1.6 miles
20 second is 0.386 mile or 2,037 feet.

The sextant hand held on a rolling ship I wonder how close most could do on most days.
Does any one know how close with handheld Sextant in real life ?

Dave

ChazzC · Tuesday at 7:55 AM

SmithDoor said:
Both sextant and transit advertised accurate
degree is 69.4 miles
One minute is 1.6 miles
20 second is 0.386 mile or 2,037 feet.

The sextant hand held on a rolling ship I wonder how close most could do on most days.
Does any one know how close with handheld Sextant in real life ?

Dave

In port (where I could see a horizon) I was able to get within a couple of hundred yards. At sea IIRC matched SatNav within maybe 1/2 mile, but on an Ammunition Ship, not a Destroyer.

SmithDoor · Tuesday at 9:34 PM

ChazzC said:
In port (where I could see a horizon) I was able to get within a couple of hundred yards. At sea IIRC matched SatNav within maybe 1/2 mile, but on an Ammunition Ship, not a Destroyer.

Interesting 1/2 mile that is 2,640. Feet. That is within 20 seconds by hand stabilizing only.

I wonder if ever use a gyro stabilizing.?

Dave

kvom · Wednesday at 3:34 AM

Accuracy depends on things other than the measured sextant angle. Having the sextant calibrated and an accurate clock are most important.

ChazzC · Wednesday at 8:14 AM

SmithDoor said:
Interesting 1/2 mile that is 2,640. Feet. That is within 20 seconds by hand stabilizing only.

I wonder if ever use a gyro stabilizing.?

Dave

Having experienced storms in the Caribbean and North Atlantic on this ship I can guarantee we didn’t have any stabilization system.

The Satellite Communications Antennas did have servos, but they were controlled by the satellite signals not gyros (it was nigty watching the antennas move during swells, rough seas and turns).

kvom said:
Accuracy depends on things other than the measured sextant angle. Having the sextant calibrated and an accurate clock are most important.

While we had chronometers, they were backups to WWV.

SmithDoor · Wednesday at 12:20 PM

ChazzC said:
Having experienced storms in the Caribbean and North Atlantic on this ship I can guarantee we didn’t have any stabilization system.

The Satellite Communications Antennas did have servos, but they were controlled by the satellite signals not gyros (it was nigty watching the antennas move during swells, rough seas and turns).

While we had chronometers, they were backups to WWV.

Calculation 1
Earth circumference(1/1) 24,900. ÷
Time in hours (1/2) 24. =
(1/3) 1,037.5 ÷
Time in minutes (1/4) 60. =
(1/5) 17.2916666667 ÷
Time in seconds(1/6) 60. =
(1/7) 0.288194444444 ×
Mile in feet (1/8) 5,280. =
(1/9) 1,521.66666667

A one second is 1,521.7 feet

Calculation 1
Earth circumference (1/1) 24,900. ÷
Degrees (1/2) 360. =
(1/3) 69.1666666667 ÷
Minutes (1/4) 60. =
(1/5) 1.15277777778 ÷
20 seconds (1/6) 3. =
Miles (1/7) 0.384259259259 ×
Numberof feet (1/8) 5,280. =
Number of feet on 20 seconds (1/9) 2,028.9

Number of feet on 20 seconds 2,028.9 feet
Plus error in time in feet is 1,521.7 feet.
Is a total error of 3,550.6 feet or in miles 0.672 miles

Have ever try hold a level to 20 seconds. ?

A machinist level 0.005 inches per foot.

Dave

SmithDoor · Wednesday at 1:30 PM

Starrett. Machinist Level
Sensitivity 0.005 in./ft., in degrees 0.0167 or 0.1" minutes or 6 seconds

Source
https://www.mcmaster.com/product/21515A24

Have you tried holding most levels at 1/2°

This why I wonder how most can hold to 20 seconds and use the Saxton at same time?

813053d1-c82a-4d57-af53-b4afe42ee2e5.d12d95a3961465b7186088e4a70fccb9 (1) (1).jpg

Dave

FYI
Omega 4.19 MHz (4194304 = 222 high frequency quartz resonator) Ships Marine Chronometer giving an autonomous accuracy of less than ± 5 seconds per year, French Navy issued,1980

Navy back to Sextant

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