Joe wrote:

Ah I see what your saying, sorry.

Let me rephrase the question

What about the other two questions - the ones where you ask for the course
*to steer* and the speed *made good*? Do you mean the course and speed made
good?


--
Wally
www.artbywally.com
www.wally.myby.co.uk

"Wally" wrote in message ...
Joe wrote:

Ah I see what your saying, sorry.

Let me rephrase the question

What about the other two questions - the ones where you ask for the course
*to steer* and the speed *made good*? Do you mean the course and speed made
good?

yes.

I guess it's a Texas thing. Us Texans were raised to think that if you
want to do something you do it, no question about it.

So when I say "you want" to steer a compass course of 080 thats what
you steer.

Sorry for your confusion.

What Im looking for in the answer is your cmg and your smg.

joe

Joe wrote:
If you want to sail a course of 080, at a speed of 10 knots and you
sail thru a current having an estimated set of 140 and a drift of two
knots
What would be your course and speed made good?.

089, 11.14 knots.


If you want to sail a course of 095 through a current having a set of
170 and a drift of 2.5 knots, using a speed of 12 knots
What would be your course and speed made good?.

106, 12.88 knots.


You want to sail a course of 265 and a speed of 15 knots through a
current having a set of 185 and a drift of 3 knots
What would be your course and speed made good?.

254, 15.8 knots.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

If you want to sail a course of 080, at a speed of 10 knots and you
sail thru a current having an ------------------ estimated
-------------------- set of 140 and a drift of two
knots
What would be your course and speed made good?.

089, 11.14 knots.

correction: that is an *estimated* 089, and an *estimated* 11.14 knots.

And even that *estimation* is off by whatever leeway you get from the wind,
whatever variation you get as to speed and direction, plus whatever variation
you get between the direction the boat points and which way it heads under
pefect conditions, plus whatever variation you get in pointing and speed due to
waves and wave direction and speed and height.

JAXAshby wrote:

correction: that is an *estimated* 089, and an *estimated* 11.14
knots.

It's accurate with respect to the mathmatical principle being employed.


And even that *estimation* is off by whatever leeway you get from the
wind, whatever variation you get as to speed and direction, plus
whatever variation you get between the direction the boat points and
which way it heads under pefect conditions, plus whatever variation
you get in pointing and speed due to waves and wave direction and
speed and height.

I am perfectly aware that DR is not precise when applied in the field.
However, the principle has to be applied precisely when working out the
vectors - to do otherwise would be to introduce another layer of potential
error. The point is to produce the best estimate you can on the basis of the
available information. To take a bunch of estimates, and then screw up the
numbers would be stupid.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

in the world of super computers, that used to be called "double-precision
[meaning calculated to 16 decimal places] guesswork".


precision math does not make guesses more accurate.

correction: that is an *estimated* 089, and an *estimated* 11.14
knots.

It's accurate with respect to the mathmatical principle being employed.


And even that *estimation* is off by whatever leeway you get from the
wind, whatever variation you get as to speed and direction, plus
whatever variation you get between the direction the boat points and
which way it heads under pefect conditions, plus whatever variation
you get in pointing and speed due to waves and wave direction and
speed and height.

I am perfectly aware that DR is not precise when applied in the field.
However, the principle has to be applied precisely when working out the
vectors - to do otherwise would be to introduce another layer of potential
error. The point is to produce the best estimate you can on the basis of the
available information. To take a bunch of estimates, and then screw up the
numbers would be stupid.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

"Wally" wrote in message ...
Joe wrote:
If you want to sail a course of 080, at a speed of 10 knots and you
sail thru a current having an estimated set of 140 and a drift of two
knots
What would be your course and speed made good?.

089,

exactly

11.14 knots.

..6 knots off, but close this aint horseshoes.


If you want to sail a course of 095 through a current having a set of
170 and a drift of 2.5 knots, using a speed of 12 knots
What would be your course and speed made good?.

106, 12.88 knots.

correct on the course. Still just a bit off on the speed.

What course should you have steered to get a cog of 095?


You want to sail a course of 265 and a speed of 15 knots through a
current having a set of 185 and a drift of 3 knots
What would be your course and speed made good?.

254,

Good, what course should you have steered to make a COG of 265?

15.8 knots.

One knot off.

Hell of alot better than Jax.

Joe

Hell of alot better than Jax.

Joe


yup, joe, you sure are one incredible alchemist. you can perform precision
math on guesses and turn them into precision guesses. I am impressed.

(JAXAshby) wrote in message ...
Hell of alot better than Jax.

Joe


yup, joe, you sure are one incredible alchemist. you can perform precision
math on guesses and turn them into precision guesses. I am impressed.

The question said the exact set and drift. They were not guesses at
all they were given.

And you can include leeway if needed.

It sure beats the hell out of a totally un-educated guess.


Joe