making turns for 15 knots

In article ,
Jim Carriere writes:
vincent p. norris wrote:
The secret squirrel part is how do you find out the blade rate to
knots correlation of everyone else's submarines.


Well, ATC can give a pilot a groundspeed readout based on tracking his
progress on the radar screen. Can't something of that sort be done
with subs?

As in time-distance using two or more fixes, yes. I think the old
fashioned way was with a piece of paper, but it is nothing for a
primitive (by today's standards) computer to do it for you with two
or several fixes.

An interesting thing about all that Target Motion Analysis jazz is
that in some ways, the old analog "Iron Idiots" were better at it than
the modern digital numerical computers. You'd crank in the inital
observed estimates, and see if the Fire Control System's generated
solution matched the target. If it didn't, you'd fudge this & that
(Target bearing & speed, for example, or range if the speed was known)
until it was tracking smoothly.


--
Pete Stickney

Without data, all you have are opinions

mah wrote:
In reading some of the novels and other books, you hear the sonar
operators saying "Making turns". How did you get a blade count
converted to knots?

Thanks

MAH

'Making turns' means set the 'enigine' to turn the shaft at a specific
number of turns per minute...

"make turns for 20 kts', tell the engine room via EOT, engine room makes
it happen, look at readout on the bridge...set number of turns which may
or may not equate to a speed..

From my time as a Midi on the John Paul Jones...summer of 1969...

Many thanks to those that replied. Still some good people out here.

MAH