How well do I need to know trigonometry?

[RNR]

Ok so recently in Maths we have been doing a lot of spherical trig, finding the shortest difference between 2 points using the cosine/sine rules etc and using the North or South pole as a 3rd point, this is not a problem. However I can't get my head round working out the 'Initial Track' (i.e angles between points) and other areas.

So my question is: Hypothetically, if I was in a vessel without any modern devices would I need to know trig inside out to navigate? Or are there ways to navigate 'old school', such as using a compass and sextant to determine my position accurately, without getting into complicated maths sums?

[Jenn]

Re: How well do I need to know trigonometry?

the trig is so you know what course to steer to get from point a to point b, so im afraid it is required

[ Post made via Mobile Device ]

[RNR]

Re: How well do I need to know trigonometry?

Is it necessary to have to know all the rules and equations off by heart though? Or does it work some other way when onboard? (Not including computer navigation equipment)

[Randomist]

Re: How well do I need to know trigonometry?

The way most modern ships are designed, with redundant system built onto redundant system, means that in order for there to be a complete failure of the ships navigational equipment a lot of things will have to go wrong first. Even after the engines stop the un-interrupted power supply batteries on the bridge should kick in and keep power upstairs alive. If these ran out and the engines hadn't returned to supply power the ship wouldn't be going anywhere, so the ability to find out where you are and where you are going becomes redundant anyway.

The spherical trig you are doing ties in with great circle theory, you have to know it because it is sometimes necessary to cross check the computers. More often than not you wouldn't have to use it. I've never had to do a GC calculation in anger at sea, the possibility is there I suppose.

To help you on the ship there is a calculator lol, and a certain number of controlled documents (books and files that have to be carried aboard by law) some of these have formule in them to work out the stuff you'll be doing in college. Don't fret yourself.

[YoungMariner]

Re: How well do I need to know trigonometry?

In all honesty, you don't need to understand it to be able to use it as a navigator, but it helps. Books such as 'Nories Tables', mean that you can minimise using a calculate and just follow a method and obtain your answer.
Over time, and with a bit of effort, you will understand it more and more.

[YoungMariner]

Re: How well do I need to know trigonometry?

I'm not in complete agreement with you Randomist. To be fair all of these navigations systems rely on one system, GPS. Regardless of how many GPS receivers you have, when GPS goes down (atmospheric interference, sun spots destroying satellites etc), you will find yourself suddenly back to basics.
Sailing to Cyprus from a nearby country which I would never want to stamp my passport, on a 52,000gt cruise ship, we lost GPS signal (suspected blockage from our uninvited military escort). Just maintained speed and gyro heading, and when we picked up the signal, we were about 7 miles north of planned track, no big deal in the area we were sailing, but had it been a transatlantic crossing....

[Randomist]

Re: How well do I need to know trigonometry?

I didn't think of that initially but yeah AM, you're right. I sail with fully integrated bridges and ECDIS and all the wonders of the modern age but it's all fed by the GPS, so yeah if the GPS fails you are back to basics, sextants and everything

[Lewis]

Re: How well do I need to know trigonometry?

on a slightly related topic do you measure angles in degrees?

[YoungMariner]

Re: How well do I need to know trigonometry?

depends on what your doing lewis, obviously when your interpreting a course it would need to be degrees, but many of the calculations are in radians.

[Lewis]

Re: How well do I need to know trigonometry?

I am just used to working in mils. Thought they were allot more accurate than degrees

[size4riggerboots]

Re: How well do I need to know trigonometry?

Degrees, minutes and seconds, or actually, degrees minutes and decimals of minutes gets you accurate as you'll ever need!