fast calculate speed ship with periscope

[Macardigan]

hi,
im from spain, bad english.

1. enemy ship moving at 90ºAOB ~aprox. (side view).
2. Put vertical line of periscope on bow ship and activate stopwatch.
3. When the stern reaches the vertical line.. stop the timer.

then:


Ship length
----------- X 1,85 = Speed in Knots.
time in sec


example:

cimmaron class tanker= 190,6 m (length)
time bow--->stern in sec= 38 seconds.

190,6 m
-------- X 1,85 = 9,27 Knots
38 sec


easy. :know:

[Fifi]

Hey, that's interesting and good to know!
...But as you need to be almost 90° angle, by the time you make your calculation and enter it in TDC, ship is in bad position to fire torp...meaning you're not anymore in ideal 90° position for best hit without DUD torpedo...

[Macardigan]

It is assumed that you already have all the calculations for firing solution, but the speed does not convince.

Do not have time? 30 or 40 seconds, divide and move the speed at tdc. It's fast.
If you shoot when the ship passes through 0 degrees, you can do 10 or 15 degrees before.

I always have time. And if the ship is far more better because you will see more time aside.

It is not necessary that the vessel is 90 ° accuracy.

You need to see the entire length and that's enough.

you'll get used.


greetings.

[Fifi]

Thanks for the tip, i'll try it :yep:

[finchOU]

Get your slide rule ready for realism!!! haha:D

[Fifi]

Macardigan, it's working quite good :up:

For a liberty ship going 6 knots at 1500m from me, i found 5.75 with your method.
Just have to round number up, and it's fine.

[Trevally.]

Hey, that's interesting and good to know!
...But as you need to be almost 90° angle, by the time you make your calculation and enter it in TDC, ship is in bad position to fire torp...meaning you're not anymore in ideal 90° position for best hit without DUD torpedo...


This will work at all angles - does not have to be 90deg.
If the angle is sharp and you can not see the centre of the bow or stern - you have to predict where it is for the start stop.

You can also avoid have to do any sums - use the u-Jagd
click on the image to see how it works (this is within TDWs UI - right click on stopwatch for it to turn into a U-Jagd)

http://imageshack.us/a/img402/4636/ujagdfd.png (http://www.youtube.com/watch?v=xI6fqazoX1E)

[Fifi]

(this is within TDWs UI - right click on stopwatch for it to turn into a U-Jagd)


An other new thing learned! :yeah:
Thanks!

[Pisces]

A small correction. The propper conversion value for meters/seconds to knots is 1.94 (=3600s/1852m) , not 1.85. So just "times 2" is good enough.

Also you don't need a perfect 90 degrees AOB. Just enough so that you can see both the bow and aft edge.

But make sure you are not moving when the periscope is looking to your beam/side.

[Macardigan]

A small correction. The propper conversion value for meters/seconds to knots is 1.94 (=3600s/1852m) , not 1.85. So just "times 2" is good enough.

Also you don't need a perfect 90 degrees AOB. Just enough so that you can see both the bow and aft edge.

But make sure you are not moving when the periscope is looking to your beam/side.


Sorry but with the value 1.94 the result fails. Although not relevant to the game.
The correct value is 1.85 for passing knots,

[Macardigan]

A small correction. The propper conversion value for meters/seconds to knots is 1.94 (=3600s/1852m) , not 1.85. So just "times 2" is good enough.

Also you don't need a perfect 90 degrees AOB. Just enough so that you can see both the bow and aft edge.

But make sure you are not moving when the periscope is looking to your beam/side.


Sorry but with the value 1.94 the result fails. Although not relevant to the game.
The correct value is 1.85 for passing knots,

Needless your comment as my explanation is for 2 sockets

[Pisces]

Sorry but with the value 1.94 the result fails. Although not relevant to the game.
The correct value is 1.85 for passing knots,Well, then the game is somehow wrong.

Needless your comment as my explanation is for 2 socketsI have no clue what you mean with this. Something must have gone wrong in translation.

[Fifi]

This will work at all angles - does not have to be 90deg.
If the angle is sharp and you can not see the centre of the bow or stern - you have to predict where it is for the start stop.

You can also avoid have to do any sums - use the u-Jagd
click on the image to see how it works (this is within TDWs UI - right click on stopwatch for it to turn into a U-Jagd)

http://imageshack.us/a/img402/4636/ujagdfd.png (http://www.youtube.com/watch?v=xI6fqazoX1E)

That's a great tool :yep: one of the most important when playing 100% realism. Thanks again for pointing this out.

[Macardigan]

pisces

Sorry.

Something must have gone wrong in translation.

[Macardigan]

fifi.

length ship 175m, then.. ???


175 m

41 sec.

then.. ??

[Fifi]

That's a great tool :yep: one of the most important when playing 100% realism. Thanks again for pointing this out.

So i found out that this U-Jagd chrono isn't so accurate for some boats speed...:oops:
To me it's useless and impossible for small cargos < 100m length...and many times it gives me a speed difference of 1 or 2 knot for others, even waiting for a nice 90° view.
It can give a good idea of speed, but not a precise one :-?

A contrario, Macardigan speed tip calculation is always accurate, even for small cargos!
Very rarely i miss out the speed :yeah: