distance between two fix

[cyan]

Originally Posted by StuM

You're the one that mentioned a kamal

I did. However, Wikipedia is just sort of a tease. Now I need a real paper book that covers the kamal, backstaff, crosstaff, and even the Polynesian stick chart (one of my favorites).

Amazon has an old hardcover from 1973, "A History of Marine Navigation", W.E. May, for about $60. I want to keep it on the boat, so paperback would be better, but those available are used and 3 times the price. (nevermind finding a Kindle edition for something like that) Any suggestions?

[KiwiKen]

"Days run usually measured by astro/ celestial nav - noon to noon, but we used to do morning twighlight, upper meridian passage (noon) and evening twighlight.
Good fun and a skill that I still practice today whilst teaching the cadets the dying art."

I agree it isn art that is becoming moribund but not dying.
Astro has the benefit that it cannot be interfered with, jammed, be subject to mechanical or electrical failure.

Any electronic equipment can be subject to failure of the electric string that makes it work - this is covered in commercial aviation by using triplex systems - the logical rationale being if one shows an error reading while not becoming inoperable the faulty system is identifiable.

The other noteworthy point is that the GPS satellites could be taken out in a case of conflict ( they are also used to provide highly accurate target acquisition) - China has successfully tested taking down a satellite. It would be strategic stupidity to leave a satellite system operational that could be used to accurately target ones installations and infrastructure.

[NevisDog]

Originally Posted by cyan

... Now I need a real paper book that covers the kamal, backstaff, crosstaff, and even the Polynesian stick chart (one of my favorites)...

In that case you'll love Trekker's 'dry rot' post #29 on CF: "Quick release VS hard tie in of tether to PFD" - it's hard to beat for pure 19th c navigation!

[Scotty Kiwi]

Originally Posted by Jim Cate

this is the commonest method:

Note the highest speed you see registered during the day. Assume that this was your average speed, so multiply the knotmeter reading by 24 to find your day's run. round the result up to the nearest even decade.

When you make landfall, repair to the nearest YC bar, and tell all who will listen that you have averaged this speed for your entire passage. If no one is impressed,come back the next day after rounding up another decade. Repeat as required.

Add in a couple of good gales (and perhaps a Tiger shark attack) and perhaps you will be respected in the manner you anticipated. Or perhaps not.

We've always just used the log readings for day's run calculations. Having a stout current helping you along gets you to the destination faster, but means little with respect to how well the boat (and the skipper) were doing.

Jim

Sounds like we have a former "friend" in common.

I knew an owner's mate out of Langkawi and Singapore, native of Kentucky (I think) for whom similar techniques and more failed to generate the desired level of attention and free drinks. Rumour had it he'd try to put other customers in some kind of wrestling hold to get them to listen and believe. Late at night, would have been in the smoking area (can't recall if they had them back then).

Not much wind at all up there during that part of the season. We doubted whether he'd even got his rags up.

Hey Chuck, if you're reading this, please return my Longines watch.