celestial navigation questions

[Laser]

So I need a bit of help
I'm a phase 4 cadet with a certain standby company and I'm doing fine until it comes to celestial navigation.
The sums I understand but I don't have the foggiest how to find a specific star. I've heard about "star finders" but I'm not sure if we have one?
Also a lack of chronometer and anyform of bridge wing with a repeater males it hard for accurate fixes.
Am I missing the point?
thanks in advance

[Martyboy]

For Cel nav you can use a sextant which I'm sure your required to have, pretty sure the star finder is also a required publication The only thing you can really get with a gyro repeater is a compass error. Might sound crazy and new age, but you can use smart phone app's to find stars.... might not be the "old school" way of doing it, but i'm off the opinion that you should use all available means to get the job done. As for Chron..... use the GPS time, it's accurate and perfect.

[EH75]

Don't think a sextant is a required piece of equipment. Know a few guys who did all their time in the north sea who were frequently on boats without them. The gyro repeater is useful for helping to locate the star. You can work out its azimuth from sight reduction tables (if you have them) and use the repeater to identify the relevant star on that azimuth before using the sextant to find it's altitude. I too did all my cadetship on a ship with fully enclosed bridge wings which made the repeaters difficult to use depending on the altitude of the body. Bit of a pain. I also used the aforementioned phone apps to help learn some of the stars. Probably cheating but meh.

[alistairuk]

So I need a bit of help
I'm a phase 4 cadet with a certain standby company and I'm doing fine until it comes to celestial navigation.
The sums I understand but I don't have the foggiest how to find a specific star. I've heard about "star finders" but I'm not sure if we have one?
Also a lack of chronometer and anyform of bridge wing with a repeater males it hard for accurate fixes.
Am I missing the point?
thanks in advance

As Martyboy said, you don't really need the repeaters other than to get the bearing for a compass error or to get an approximate bearing to see what a star is.

The Star Finder you probably have somewhere, its a cardboard square about 30cm x 30cm and a bundle of 5/6 transparent sheets. You work out the LHA of Aries from the Almanac and then use the appropriate transparent sheet for your latitude to get the bearing of the stars.

I recommend picking some of the bright objects; jupiter, venus, mars, the moon, cappella as these are usually easy to spot once you know where to look. Most people will use the same few bodies as you can quickly identify them when you're used to it.

[Martyboy]

Sun and moon! That'll do me haha!

[Laser]

As Martyboy said, you don't really need the repeaters other than to get the bearing for a compass error or to get an approximate bearing to see what a star is.

The Star Finder you probably have somewhere, its a cardboard square about 30cm x 30cm and a bundle of 5/6 transparent sheets. You work out the LHA of Aries from the Almanac and then use the appropriate transparent sheet for your latitude to get the bearing of the stars.

I recommend picking some of the bright objects; jupiter, venus, mars, the moon, cappella as these are usually easy to spot once you know where to look. Most people will use the same few bodies as you can quickly identify them when you're used to it.

I asked the 2/o and he said He's never seen one on any of the ships he's been on in the north sea.
We have sextant so That's a start.
I can find "the plough" and Orion's belt pretty easy but I'll have to practice finding the planets.

[YoungMariner]

Personally I use the Philips Pocket Star Atlas which can be bought on Amazon for a fiver, very very easy to use. If you work on ships without a sextant, drop and email to your company training officer to ask if they can purchase one for the cadets to use.
If the worst comes to the worst, you'll just have to do some mock calculations in your navigation workbook to prove that part of the training. Many officers aren't that interested in celestial navigation so won't be able to teach you much, but you will probably come across a few keen people who enjoy getting out the sextant and will show you the correct methods.

It's no dark art, it's actually very simple. I use a ruler held at arms length against Polaris and the horizon to teach cadets in the northern hemisphere how simple it is.

[Martyboy]

It's no dark art, it's actually very simple. I use a ruler held at arms length against Polaris and the horizon to teach cadets in the northern hemisphere how simple it is.

Sounds like witch craft to me, you've even added a wand into the occasion!!! :P

[Silvertop]

I always used a copy of Bernard's Nautical Star Chart. Very useful, shows links between stars so you can learn then by patterns across the sky. Saying that nowadays I use Astronav on my iPad, awesome app!!!

[PatrickW]

I can find "the plough" and Orion's belt pretty easy but I'll have to practice finding the planets.

.
If you form a line between the two end stars of the plough (as in the pan bit!) And follow it straight up the first star you get is Polaris. And following the arc of the 'pan handle' of the plough you get to Arcturus. Don't know if that's any help!

[Laser]

Thanks for all the replies guys.
I downloaded a good soon for finding the stars lasnight.
Any help with my azimuth problem?
We don't have reduction tables but u found some on the internet.
Ant help on how to use them?

[Martyboy]

I never used reduction tables I know that's not really much help to you, but I passed my orals no probs without them.

[Clanky]

If you are in an area with phone signal then you can use Google Sky Map to help you identify stars initially while you are learning, but I imagine examiners might frown upon you pulling out your smartphone in an oral.

[Laser]

Thanks again for the replies. I'm going to do the sight reduction method. Can anyone give me any links or tell me how to use these sight reduction tables please?

[Silvertop]

From memory the books have a good description in them of how to use them!! Otherwise likely something online to help. I never used this method much so don't have a pro forma for it.