Speed Calculations in seconds using only stopwatch and scope.

[Pirate Roberts]

I really searched the threads before posting this to make sure it wasnt covered elsewhere but this is cracking me up. 3min 15 s rule yes this works great but needs two separate signtings with range estimates (which on the short term ie attack approach are always iffy) and scope needs to go up twice (assuming nobody is actually leaving scope up for the eternity of three minutes 15). Long range tracking obviously the best by taking multiple running map fixes then calculating speed=dist/time. Great during approach end around or shadowing but needs time. Useless on final aproach. Other methods including sin functions with AOB etc are mathematicaly correct , but really! on final approach thats a bit cumbersome.


Does anyone else do it this way.

1. Stop or be very slow <1kt. (you should be anyway with scope up)
2. Up scope
3. Mark on ship bow START watch dont move scope
4. Let ship pass reticule mark on stern STOP watch (the actual pointy part, if AOB is acute estimate where it is as it wont be what you see against the skyline but slightly behind the bulk of the ship.)
5. down scope

speed = ship length/STOPWATCH time.

knots=ship_LOA/STOPWATCH_reading x 60 x 60 / 1852

This is very accurate even with realy bad AOB (which you dont need to know, also range is not important)
It works because despite the range or AOB ships sterns almost always end up going over the exact same point the bow went over (which you dont need to know just its relative bearing because it will be the same point)


I played SH1 and SH2 for years and couldn't figure out how the WOs in SH3 get a great speed estimate in 15seconds to 30 seconds. I thought it was a game cheat for the WO furiously calculating from previous running fixes. Then Duh! I use it myself on my own sailboat and it works great.

If the ship is going so slow it would take 40s to pass and you dont want scope up that long just mark half its lenght in half the time. The faster the ship goes the quicker the reading.


Does anyone else do it this way?

[siege00]

I think lots of people use this method, but maybe without the manual maths. :03:

The U-Jagd tools and the various implementations of them feature a marked stopwatch that has readings based on hull length (100, 150, 200, etc) and the RAOBF (range and AOB finder) tool that drops down around the periscope view. Most of the UIs that I've seen have some implementation of 1 of the above, if not both. Example: http://www.subsim.com/radioroom/showthread.php?t=123373

I've found it to be the best way to go after getting the vessel properly identified or if you need to get a rapid solution ready.

[geosub1978]

Easier:

1. Count bearing and range of the target and place a mark on the map.
2. Do the same after 3 minutes and plot another mark.

3. Measure the distance between the marks (kilometers) and divide by 0,914.=SPEED in knots!

If you plot at 1 minute interval, multiply by x3!

[Pisces]

Aside from not turning the scope, you should also be sure the boat itself is not turning. So "rudder amidship".

You can have a bit of speed, but then the scope must be pointing to 0 degrees or 180. And the boat must be turned so the scope is in front of the target beforehand to do this. Then your speed doesn't influence the result.

If you work out those divisions and multiplications then you'll find that you must multiply by 1.94 (=3600/1852) to get from meters per second to knots. So multiplying by 2 is just too easy and accurate enough. ;) Even doable in your mind.

[Pirate Roberts]

siege00 ahh the U-jagd tools look realy interesting. I doubt if id use the stopwatch thing much because its already pretty easy to just line them up on the verticle reticule and do the math but the range and AOB rotating slide calculator looks really interesting. I downloaded and read the manual will try them out. The manual stops at GWX2.0 Do you know if they are direct GWX 3.0 gold supported or if you have to run the GWX DIY install

[Pirate Roberts]

Pisces yeah I did that math too, its 3%, unless its going 22kts and very far away 2 works great. Untill I get the U-jagd working it cetainly saves some calculator time.

[siege00]

siege00 ahh the U-jagd tools look realy interesting. I doubt if id use the stopwatch thing much because its already pretty easy to just line them up on the verticle reticule and do the math but the range and AOB rotating slide calculator looks really interesting. I downloaded and read the manual will try them out. The manual stops at GWX2.0 Do you know if they are direct GWX 3.0 gold supported or if you have to run the GWX DIY install

Tailmange created a video tutorial on YT: https://www.youtube.com/watch?v=uNRp6TzXGZk that discusses the tools, but if you can track them down, the actual OLC video tutorials that OneLifeCrisis put out are really good and even briefly discusses the attack disk.

[Pirate Roberts]

Whats the difference between the OLC and the U-jagd mods?

[Pirate Roberts]

Reason Im asking is I watched the video on the OLC youtube link you sent it looks very similar to the pics in the U-jagd manual so I'm not clear on whats the difference or even if they are the same mod

[siege00]

That's a good question. They definitely have a lot in common, though I believe OLC is a complete UI rework. The tools should all work the same, though they may be slightly different between versions, ie. for the RAOBF wheel, the markings may be in different locations, and for the recognition manual, I believe OLC's version has the mast heights already doubled so you don't have to do it yourself. If you have known locations, ie. the Torpedo school, you can practice with the tools and make sure that you're using them correctly.