Circumnavigation 52 : Finding the Way

[C James]

Chapter 52, "Finding the Way", is up.

 

The naked journey continues.

[hh5]

Trevor is so technical to solve for the rudiments of navigation ... that improvised sextan needs to be an arc of at least 180 degrees

 

so he's six foot ... no fat on him to let him last an extra month or two ...

 

would it not be funny if he missed the islands and sails to austraila

 

all he has to do is tie himself to the mast but gosh he should come across a ship

 

some gay sailor that would take naked pity on him

 

 

[Red_A]

.. that improvised sextan needs to be an arc of at least 180 degrees

 

The astrolade was used by navigators to measure the angle between the sun and the horizon, it is a direct measurement, as the maximun angle between sun and horizon is 90 degrees, it only needs to be a 90 degree "quadrant". This is a picture of a early navigational astrolade 1388.

 

 

 

1388 astrolade navigational

[hh5]

The astrolade was used by navigators to measure the angle between the sun and the horizon, it is a direct measurement, as the maximun angle between sun and horizon is 90 degrees, it only needs to be a 90 degree "quadrant". This is a picture of a early navigational astrolade 1388.

 

1388 astrolade navigational

 

It looks weird that there will be a gap between the measurements and the plumb line when sighting a star

[Benji]

Chapter 52, "Finding the Way", is up.

 

The naked journey continues.

 

........Great chapter! I hope Jim and Dirks lawyer can get them released on bond. I wonder if the P.I. he hires can find anything worth while, like discovering a break-in at the Chandery. Will they be able to hold off the information on the Aries? I'm wondering if the Egyptian authorities will contact Gonzales and tell him more information, like they found out the bomb was constructed in Egypt? Will Captain Ali's crew sense his suspicions and revolt?

 

If the ever so resourceful Trevor estimates his speed at now being at 3 knots, then he is doing about 3.45 miles an hour. At that rate he can travel @ 138 miles every 24 hours, it could take him as little time as 5-6 days to make landfall. Trevor has already got another 3 days behind him and the pirates, so I guess it is safe to assume that the Reunion will not be with them, but a small island.

[hh5]

........Great chapter! I hope Jim and Dirks lawyer can get them released on bond. I wonder if the P.I. he hires can find anything worth while, like discovering a break-in at the Chandery. Will they be able to hold off the information on the Aries? I'm wondering if the Egyptian authorities will contact Gonzales and tell him more information, like they found out the bomb was constructed in Egypt? Will Captain Ali's crew sense his suspicions and revolt?

 

If the ever so resourceful Trevor estimates his speed at now being at 3 knots, then he is doing about 3.45 miles an hour. At that rate he can travel @ 138 miles every 24 hours, it could take him as little time as 5-6 days to make landfall. Trevor has already got another 3 days behind him and the pirates, so I guess it is safe to assume that the Reunion will not be with them, but a small island.

 

If he misses Reunion island ... he has a couple of icy islands he can stop by on his way to austrailia ... maybe he might run into a anartica science vessel along the way ... some gay scientist eager to warm up a naked trevor ... hehe will Trevor over come bashfulness in front of people?

[jkeeling]

Good chapter. Did I read the chapter right and trev has been on top of the salon? I'm wondering why he hasn't thought of the eprib (spelling) on top of the salon.

[Benji]

Good chapter. Did I read the chapter right and trev has been on top of the salon? I'm wondering why he hasn't thought of the eprib (spelling) on top of the salon.

 

.........Speaking of which!! Damn pirates did not leave any sunblock lotion for poor Trevor, Hmmm, could he get a sever case of sunburn in the nether regions??

[hh5]

.........Speaking of which!! Damn pirates did not leave any sunblock lotion for poor Trevor, Hmmm, could he get a sever case of sunburn in the nether regions??

 

He not looking to father any ... unless he forced under gun ... that would prove how gay he is or isn't

[Benji]

He not looking to father any ... unless he forced under gun ... that would prove how gay he is or isn't

 

............Sunburn is nothing to laugh at, especially if it is regions not ever exposed to the sun! It would not matter what if he ever thought of being the father of a child. It is the pain of the sunburn that matters. Might keep him awake a lot though! :wacko:

[C James]

It looks weird that there will be a gap between the measurements and the plumb line when sighting a star

 

There won't... when he lines up on the sun, the plumb line falls on the arc.

 

........Great chapter! I hope Jim and Dirks lawyer can get them released on bond. I wonder if the P.I. he hires can find anything worth while, like discovering a break-in at the Chandery. Will they be able to hold off the information on the Aries? I'm wondering if the Egyptian authorities will contact Gonzales and tell him more information, like they found out the bomb was constructed in Egypt? Will Captain Ali's crew sense his suspicions and revolt?

 

If the ever so resourceful Trevor estimates his speed at now being at 3 knots, then he is doing about 3.45 miles an hour. At that rate he can travel @ 138 miles every 24 hours, it could take him as little time as 5-6 days to make landfall. Trevor has already got another 3 days behind him and the pirates, so I guess it is safe to assume that the Reunion will not be with them, but a small island.

 

No chance of getting them released on bod while they are on the run, and Dirk needs to stay out of their hands.

And yep, the Egyptians are still investigating...

 

The pirates, revolt? Do you see the danger there? All kinds of bad puns from me about how the pirates are revolting...

 

If he misses Reunion island ... he has a couple of icy islands he can stop by on his way to austrailia ... maybe he might run into a anartica science vessel along the way ... some gay scientist eager to warm up a naked trevor ... hehe will Trevor over come bashfulness in front of people?

 

The only problem is, arriving naked in icy islands would be kind of.. chilly.

 

Good chapter. Did I read the chapter right and trev has been on top of the salon? I'm wondering why he hasn't thought of the eprib (spelling) on top of the salon.

 

Yep, he'd have seen any EPIRB. All his EPIRBS are gone. The pirates pretty well stripped Atlantis. But, at least he was able to rescue his garlic crusher.

 

***********

 

Anyone have any questions on the navigation, area, or anything? Trevor still has some navigation issues to solve...

 

Oh, here's a trivia question... The island of Reunion was mentioned in one of my prior novels. Anyone remember which one?

[wkramer]

Wow, what a tremendous story. i have now caught up after reading the first 49 chapters after finding them. the story is wonderful and energizing to follow. is there a way to be posted of new chapters?

 

Wijnand

[TalonRider]

CJ generally posts a new chapter late Monday night/early Tuesday morning. So you can usually find the latest posting on Tuesday.

 

Another option is to subscribe to Hosted Authors Announcement forum. The drawback here is, you will receive notification of all authors postings.

[Flipper]

"Oh, here's a trivia question... The island of Reunion was mentioned in one of my prior novels. Anyone remember which one? "

Changing Lanes

 

And for my prize ....... if anyone could tell me how to include the poster's name date + time when pasting quotes that would be cool

[C James]

Wow, what a tremendous story. i have now caught up after reading the first 49 chapters after finding them. the story is wonderful and energizing to follow. is there a way to be posted of new chapters?

 

Wijnand

 

Hello and welcome to our forum!

 

Thanks!!

 

Like Talonrider said, a chapter should appear every Tuesday. Occasionally I do run a day or so late, but not often.

 

Changing Lanes

 

And for my prize ....... if anyone could tell me how to include the poster's name date + time when pasting quotes that would be cool

 

Great memory!!! I'm surprised anyone got that.

 

Okay, to quote... look to the bottom right of this post. There's a row of buttons just under the text frame (Assuming you're not reading the site in text mode). One says "reply" and to the right of it is "multiquote". To reply (with name and date added) to one post, hit "reply" on that post. It should quote it for you.

 

To reply to several posts, click on "multiquote" on each post. (the button should change color when you do). When you've selected all the posts you want to reply to, scroll to the bottom of the page and click on "Add reply".

 

Hrmmm, I think it's time to release the title of chapter 53... "Reunion or Bust!"

[wildone]

Hey CJ, Thanks for the chapter

 

I wasn't sure until you posted here about the EPRIB that we knew for sure that the one mounted would be gone.

 

So we now know that Dirk is waiting for the Statue of Limitations to expire on something to do with the Ares. He didn't mention about Rachel, so I take it he may have collected some insurance money for the Ares, or maybe is waiting for the payout?

 

I'm curious, and I ask this in a non judgmental way, but did anyone else get lost with the technical stuff about the navigation. I guess i don't even understand latitude and longitude, so everything else was another language for me.:wacko:

 

I guess we will find out if Trevor will make a shocking entrance to Reunion island, or will it be bust.

 

Thanks again CJ

 

 

 

 

[C James]

Hey CJ, Thanks for the chapter

 

I wasn't sure until you posted here about the EPRIB that we knew for sure that the one mounted would be gone.

 

Yep, all EPIRBS are gone, along with all of Atlantis's electronics, even the solar cells and batteries. The pirates basically stripped Atlantis bare.

 

So we now know that Dirk is waiting for the Statue of Limitations to expire on something to do with the Ares. He didn't mention about Rachel, so I take it he may have collected some insurance money for the Ares, or maybe is waiting for the payout?

 

I can't really say, other than yes, Dirk is waiting for the statutes of limitations to run out. I can say that, over the next two chapters, we learn exactly what the crimes involved were.

 

I guess we will find out if Trevor will make a shocking entrance to Reunion island, or will it be bust.

 

We'll soon learn the naked truth.

 

I'm curious, and I ask this in a non judgmental way, but did anyone else get lost with the technical stuff about the navigation. I guess i don't even understand latitude and longitude, so everything else was another language for me.:wacko:

 

Here's a link that explains latitude and longitude very well (and briefly) and explains about the coordinate system

 

I'd very much like others to weigh in on this too... Please. I need to know what's not coming across, so I can clear it up. Please, if anyone has any questions on this, post them. The navigational techniques Trevor is using (we see a couple of other techniques in 53) are real, and work. They can save your life if you find yourself lost, either at sea or on land, which is one of the reasons I want to be sure they come across okay.

[Flipper]

Okay, to quote... look to the bottom right of this post. There's a row of buttons just under the text frame (Assuming you're not reading the site in text mode). One says "reply" and to the right of it is "multiquote". To reply (with name and date added) to one post, hit "reply" on that post. It should quote it for you.

 

To reply to several posts, click on "multiquote" on each post. (the button should change color when you do). When you've selected all

Thanks CJ - works a treat

 

I'd very much like others to weigh in on this too... Please. I need to know what's not coming across, so I can clear it up. Please, if anyone has any questions on this, post them. The navigational techniques Trevor is using (we see a couple of other techniques in 53) are real, and work. They can save your life if you find yourself lost, either at sea or on land, which is one of the reasons I want to be sure they come across okay.

 

OK then - I'm a bit (well quite a bit actually) sceptical that Trev, clever and resourceful as he is (not to mention indestructible, sexy, naked and sweaty ) could get sufficiently accurate readings from his homemade astrolabe / sexytant thingy to be within the margin of error required realistically to avoid missing Reunion. Maybe on the deck of the Queen Mary, in calm seas - but on the moving deck of his catamaran? With a swinging dangly thing to read off the scale with precision? It will surely be swinging around as the boat will be in constant movement in all planes, including towards and away from the paper scale as well as up and down the scale? How do you get a true average reading from that? I mean it sounds OK on paper, but in the real world?

[C James]

Thanks CJ - works a treat

 

 

 

OK then - I'm a bit (well quite a bit actually) skeptical that Trev, clever and resourceful as he is (not to mention indestructible, sexy, naked and sweaty ) could get sufficiently accurate readings from his homemade astrolabe / sexytant thingy to be within the margin of error required realistically to avoid missing Reunion. Maybe on the deck of the Queen Mary, in calm seas - but on the moving deck of his catamaran? With a swinging dangly thing to read off the scale with precision? It will surely be swinging around as the boat will be in constant movement in all planes, including towards and away from the paper scale as well as up and down the scale? How do you get a true average reading from that? I mean it sounds OK on paper, but in the real world?

 

You raise some very good points!

 

If anything does not work in real life, then I've screwed up, badly.

 

I've tried the astrolabe, ON DRY LAND, and it's pretty decent the way Trevor is using it; aiming the barrel at the sun so it casts a round spot of light on his stomach (that gives an effective sight length of a couple of feet). That gives him a true line on the sun. As a guess, I'd say it's accurate to within a degree or so. On land.

 

A big catamaran like Atlantis is very stable, especially in calm seas, but there is of course some motion, and you're 100% right, motion degrades the accuracy. So, let's say, for a round number, that the motion of the sea triples the inaccuracy. He's still within three degrees for latitude. (longitude can't be determined with an Astrolabe... we'll find out about that in 53, along with the issue that the sun's apparent height in the sky changes with the seasons). But, for now, let's say 3 degrees on latitude. A degree of latitude is 69 statute (not nautical) miles. So, Trevor could calculate his position as much as 207 miles north or south of actual. That's a lot. But, he's taking numerous sightings, throwing out the outliers, and averaging... That should, most of the time, get him to within two degrees, or 138 miles north or south of his actual position. His guess is he's accurate to within a hundred miles, which isn't far off; he won't be off by the maximum ever time; statistically, his error will almost always be less than the max possible error, because the error is a random function. (So, for him to be off by maximum, it's like rolling a pair of dice and coming up 12; very possible, but it's not going to happen every time). So, at least half the time, it's safe to say his calculated position will be within a hundred miles of his actual position. (if he drew a line, north to south, 200 miles long, he'd be somewhere on it).

 

The use of the astrolabe is simple. For this we're going to assume it's the day of the Equinox, September 23rd, when the sun is directly over the equator. (we'll see how to correct for date in 53). Trevor sights on the sun, and at it's highest point in the sky, the average of his sightings shows that it's at 80 degrees above the northern horizon (90 is straight up). On his astrolabe scale, he gets 10 degrees (the difference between vertical and the sun). That means he's 10 degrees south of the equator.

 

Now, to find Reunion... the island is quite mountainous. and about 40 miles wide on his approach vector. Given decent visibility, he could see it from over 50 miles away. But, let's knock that down a bit... say 40. That means his effective target is 120 miles wide. There are other factors as well; tropical islands often spawn thunderstorms in the afternoons, and those can be seen from even further away (even atolls do this... I've seen it many times). But, that high pressure system mentioned would dampen that, so let's toss that factor out. Same with the city lights at night (if there are high clouds, you can see the glow from a hundred miles away).

 

So, we're looking at a target roughly 120 miles across. Miss by more than 60 miles either side of the center of the target, and you miss it. Trevor's accuracy is (talking latitude only for simplicity here) 100 miles. However, if Trevor's track is 60 miles to the side, he might not be able to come close enough to the island to be seen by shore traffic and rescued... So, let's reduce that further, and make the usable target 100 miles wide. So, we can guess (yep, I'm extrapolating here) as high as a 50% chance of either reaching Reunion directly, or coming close enough to be sighted and rescued. I'd feel comfortable saying he's got as much as a 40% chance, assuming, that is, that he makes no mistakes.

 

He only has one shot at Reunion... he can't go upwind, so once he's past, he's past. And from there, the winds and current would carry him southeast, in a crippled, stripped, unseaworthy, half-sinking boat, no supplies, and no clothes, into the heart of the polar southern ocean; the roaring forties and furious fifties. And, the worst seas on earth, bar none, are in roaring forties and furious fifties south of the Indian ocean (and that netting sail would be shredded in minutes by the massive storms that occur there).

 

[Benji]

You raise some very good points!

 

If anything does not work in real life, then I've screwed up, badly.

 

I've tried the astrolabe, ON DRY LAND, and it's pretty decent the way Trevor is using it; aiming the barrel at the sun so it casts a round spot of light on his stomach (that gives an effective sight length of a couple of feet). That gives him a true line on the sun. As a guess, I'd say it's accurate to within a degree or so. On land.

 

A big catamaran like Atlantis is very stable, especially in calm seas, but there is of course some motion, and you're 100% right, motion degrades the accuracy. So, let's say, for a round number, that the motion of the sea triples the inaccuracy. He's still within three degrees for latitude. (longitude can't be determined with an Astrolabe... we'll find out about that in 53, along with the issue that the sun's apparent height in the sky changes with the seasons). But, for now, let's say 3 degrees on latitude. A degree of latitude is 69 statute (not nautical) miles. So, Trevor could calculate his position as much as 207 miles north or south of actual. That's a lot. But, he's taking numerous sightings, throwing out the outliers, and averaging... That should, most of the time, get him to within two degrees, or 138 miles north or south of his actual position. His guess is he's accurate to within a hundred miles, which isn't far off; he won't be off by the maximum ever time; statistically, his error will almost always be less than the max possible error, because the error is a random function. (So, for him to be off by maximum, it's like rolling a pair of dice and coming up 12; very possible, but it's not going to happen every time). So, at least half the time, it's safe to say his calculated position will be within a hundred miles of his actual position. (if he drew a line, north to south, 200 miles long, he'd be somewhere on it).

 

The use of the astrolabe is simple. For this we're going to assume it's the day of the Equinox, September 23rd, when the sun is directly over the equator. (we'll see how to correct for date in 53). Trevor sights on the sun, and at it's highest point in the sky, the average of his sightings shows that it's at 80 degrees above the northern horizon (90 is straight up). On his astrolabe scale, he gets 10 degrees (the difference between vertical and the sun). That means he's 10 degrees south of the equator.

 

Now, to find Reunion... the island is quite mountainous. and about 40 miles wide on his approach vector. Given decent visibility, he could see it from over 50 miles away. But, let's knock that down a bit... say 40. That means his effective target is 120 miles wide. There are other factors as well; tropical islands often spawn thunderstorms in the afternoons, and those can be seen from even further away (even atolls do this... I've seen it many times). But, that high pressure system mentioned would dampen that, so let's toss that factor out. Same with the city lights at night (if there are high clouds, you can see the glow from a hundred miles away).

 

So, we're looking at a target roughly 120 miles across. Miss by more than 60 miles either side of the center of the target, and you miss it. Trevor's accuracy is (talking latitude only for simplicity here) 100 miles. However, if Trevor's track is 60 miles to the side, he might not be able to come close enough to the island to be seen by shore traffic and rescued... So, let's reduce that further, and make the usable target 100 miles wide. So, we can guess (yep, I'm extrapolating here) as high as a 50% chance of either reaching Reunion directly, or coming close enough to be sighted and rescued. I'd feel comfortable saying he's got as much as a 40% chance, assuming, that is, that he makes no mistakes.

 

He only has one shot at Reunion... he can't go upwind, so once he's past, he's past. And from there, the winds and current would carry him southeast, in a crippled, stripped, unseaworthy, half-sinking boat, no supplies, and no clothes, into the heart of the polar southern ocean; the roaring forties and furious fifties. And, the worst seas on earth, bar none, are in roaring forties and furious fifties south of the Indian ocean (and that netting sail would be shredded in minutes by the massive storms that occur there).

 

 

...........So maybe 50-50 shot at a 'Reunion' (love the name of the island) I'm going to lean towards a rescue as he comes close, the broken mirror will come in handy! He will be so happy at being rescued, he will forget that he is naked!

[Flipper]

... longitude can't be determined with an Astrolabe... we'll find out about that in 53 ....

 

Trev's sailing (more or less) along a line of longitude which, if it's one that passes through or close by Reunion, means he'll be saved

 

But if he's on the "wrong" line of longitude then the astrolabe won't tell him and he's doooomed

 

So Trev has to discover a solution to the problem of longitude in chapter 53.

[C James]

...........So maybe 50-50 shot at a 'Reunion' (love the name of the island) I'm going to lean towards a rescue as he comes close, the broken mirror will come in handy! He will be so happy at being rescued, he will forget that he is naked!

 

I've never been to Reunion, but I'd love to... from the pictures, it looks very much like Hawaii.

Here's a photo I found online.

 

 

Trev's sailing (more or less) along a line of longitude which, if it's one that passes through or close by Reunion, means he'll be saved

 

But if he's on the "wrong" line of longitude then the astrolabe won't tell him and he's doooomed

 

So Trev has to discover a solution to the problem of longitude in chapter 53.

 

He's going to need to approach Reunion from the northwest, heading southeast. So, he'll need latitude and longitude.

 

The winds make it tricky.. he's following a course that's an arc, bending west towards Madagascar, then following the wind as it bears towards the southeast.

 

 

The shaded area is what was within his ability to reach at first (by steering as much as he could to either side of the wind track) and the red line is his planned course.

 

He does have a further advantage; he can estimate his speed fairly well by eye (from his experience) to within about 20% of actual. So, he can estimate his distance covered. It's an additional navigational datapoint, and it does help a little.

 

Basically, he's in a situation where he has to do everything right the first time, and it still might not be enough. However, the wind leave him little option; Reunion is the only land within the shaded area (the area he can reach).

 

and he'd better hope for help when he gets close, otherwise he's heading for Reunions northwest coast, which is kind of rugged; in many places, just soaring, ah, vertical rocky escarpments. However, there are some ports and beaches as well... plus some reefs. He's using a map, not a chart, so he can't tell what the coastline is like. He's facing a bit of a challenge.

[wildone]

Okay, if I was confused before, I'm really confused now

 

I guess I understand in basics what latitude and longitude are, but I imagine the difference between one degree on either of them is huge. If I'm correct, there is 90 degrees north and south of the equator for latitude and 180 degrees left and right of the Prime Meridian (for a total of 360 degrees) for longitude. How much space is between each line of lat. and long. ? Miles or km?

 

Then, if I read correctly, Trevor use the astrolabe to pinpoint his longitude and used the compass to measure his direction and guessed his speed. Now he did this during the day with the sun, as well as at night using the southern cross (is that the actual geographical south, or is it off like Polaris), do both readings tell him the same thing? Then I seem to recall their is geographical north, magnetic north and true north. I'm sooooo confused and I'm in the wrong hemisphere .

 

Does the astrolabe replace the sextant? If so, is it a simpler version of the latter?

 

Usually when someone talks about geographic position I skip over it, because I just don't understand it. I am curious though since this seems to be a major part of the story.

 

Trevor's life depends on me understanding it

 

Help!!!

[C James]

Okay, if I was confused before, I'm really confused now

 

I guess I understand in basics what latitude and longitude are, but I imagine the difference between one degree on either of them is huge. If I'm correct, there is 90 degrees north and south of the equator for latitude and 180 degrees left and right of the Prime Meridian (for a total of 360 degrees) for longitude. How much space is between each line of lat. and long. ? Miles or km?

 

Degrees of latitude are always 69 (that's rounded to the nearest mile) standard (statute) miles. (111 of those strange kilometer things that some folks insist on using. )

 

Longitude is trickier. It to is 69 miles at the equator. But, if you look at a globe, or a non-Mercator-projection map, you'll see that lines of longitude converge at the poles. So, the further away from the equator you get, the smaller the number of miles in a degree of longitude. At 45 degrees north or south, you're halfway to the pole, so a degree is half as large as at the equator.

 

Then, if I read correctly, Trevor use the astrolabe to pinpoint his longitude

 

Nope, he uses the astrolabe for latitude (distance from the equator, south in his case). It's useless for longitude. (east-west). He presently (chapter 52) does not have a means for determining longitude (that's covered in the next chapter).

 

and used the compass to measure his direction and guessed his speed. Now he did this during the day with the sun, as well as at night using the southern cross (is that the actual geographical south, or is it off like Polaris),

do both readings tell him the same thing? Then I seem to recall their is geographical north, magnetic north and true north. I'm sooooo confused and I'm in the wrong hemisphere .

 

The compass will point to magnetic north, which isn't geographic north. For this, I blame Canada! (the north magnetic pole is, after all, in your territory! Well, until recently it was... It's presently off Ellesmere island and heading away at about 40 miles a year.. you should really take better care of it!) However, a compass is also affected by magnetic deviation, so may not always point at magnetic north. The geographic north pole is the true north pole, and is located at 90 degrees north. The true north and south poles are basically the earth's axis of rotation. Polaris (the pole star) appears directly over (less than a degree off). If you find Polaris in the sky, look down (to the horizon) below it, and that's true north. The Southern Cross can be used to find true south, basically four and a half times the length of the top to bottom distance, measured down from the base, and you are at the southern celestial pole.

 

Geographical north and true north are the same thing.

 

Trevor is south of the equator, so he's in the Southern Hemisphere.

 

Does the astrolabe replace the sextant? If so, is it a simpler version of the latter?

Yes, it's a much simpler device, that does some of what a sextant can do. A sextant sights on both the horizon (in some cases an artificial horizon) and the sun or a star, giving an angle between. It's far more accurate than an astrolabe. Trevor had one, but the pirates took it. There are quite a few different kinds.

 

Usually when someone talks about geographic position I skip over it, because I just don't understand it. I am curious though since this seems to be a major part of the story.

 

It is... Trevor is having to develop a means of navigation from scratch. It's part of the story, but the methods used work, so one of my goals it to explain them in the narration understandably. Who knows, someone might read this, and then years later find themselves in an emergency at sea or lost on land, and make use of them. It's also important for the plot.

 

Trevor's life depends on me understanding it

 

Poor Trevor!! He's in more danger than he knows!

[Benji]

Okay, if I was confused before, I'm really confused now

 

I guess I understand in basics what latitude and longitude are, but I imagine the difference between one degree on either of them is huge. If I'm correct, there is 90 degrees north and south of the equator for latitude and 180 degrees left and right of the Prime Meridian (for a total of 360 degrees) for longitude. How much space is between each line of lat. and long. ? Miles or km?

 

Then, if I read correctly, Trevor use the astrolabe to pinpoint his longitude and used the compass to measure his direction and guessed his speed. Now he did this during the day with the sun, as well as at night using the southern cross (is that the actual geographical south, or is it off like Polaris), do both readings tell him the same thing? Then I seem to recall their is geographical north, magnetic north and true north. I'm sooooo confused and I'm in the wrong hemisphere .

 

Does the astrolabe replace the sextant? If so, is it a simpler version of the latter?

 

Usually when someone talks about geographic position I skip over it, because I just don't understand it. I am curious though since this seems to be a major part of the story.

 

Trevor's life depends on me understanding it

 

Help!!!

 

...............My only nightmare is that if Trevor passes the island during the night while sleeping, I think the clue left by the goat here is 'Reunion' an island name but still a clue in Trevor's rescue, given the wide range of misses and passes by the island the only logical conclusion is a rescue, from the Island. And a bare naked Trevor will be pleased to see his rescuers, although they may not be pleased at what they see.