SUBSIM Radio Room Forums - How to calculate speed target at 100% realism?

Quote:

Originally Posted by stellaferoxx (Post 2777268)

Hi there,

I always play at 100% realism so no ships on the map etc. In every other subsim there is the length of the ship which you can let pass through the periscope and calculate the speed of the target. I see no mentioning of the length in de shipmanual. How am I supposed to calculate the speed?

I don't want to ping the ship to know the distance and using radar seems to be a little odd. I dont want to use the 4 bearing method every time to calculate the speed.

thx for your answers!

First question is what are you running/ ?stock, mods? which mods? TMO? FOTRS?

I run TMO with my update I recently released and patrol without map contacts most of the time, prob 75% or so and have great success overall.

In TMO, if running in a Tambor, Gar, Gato, Balao or Tench, you have the excellent radar range unit and 3D TDC, which makes getting accurate range with radar and plotting speed is easy once get through learning curve. I'll have to search for the link to the original mod (mod was incorporated into TMO long ago) I remember it has instructions.

For pre radar or visual only. Well, I take into account the accumulation of all data.

First, I eyeball the target, judge its movements, wake etc, Gives a decent indication.

Sound will report speeds as slow to very fast. 0-7.9 knots is slow, 8-11.8 knots is medium, 12-21 knots is fast, above is very fast. Merchants are nearly always moving 6-10 kts, typically around 8 or 9.

I take my bearings mark relative position on map , time for three minutes, raise scope about 2:45 and mark on map at 3 minute mark. Draw a line from mark to mark.

Then I will get input from crew. Take stadimeter reading, bring split image down to the masts tops on freighters, tallest point on warships, click send bearing/range to TDC button and start the stop watch as well for three minutes. After three minutes, take another bearing/range with stadimeter, send to TDC. Then click the red button on the TDC where set target speed, and click the red right hand button with the stopwatch, you will then see a message in the dialogue box at top of screen, telling you "Target speed is so and so knots , sir." See if that is close to what you have plotted.

Now, the issue with the crews speed plot is it is error prone due to the screwy way the stadimeter was implemented into SH 4 in stock. MODS corrected it as much as possible but still very finicky to say that least. However, if you have target plotted at 9 knots and your crew is telling you something close like 8.5 or 9.5 , you know you are in ball park.

Continue plotting and repeating process, its how real subs had to do it after all.

Also, fire a spread, as real subs did to account for inevitable speed errors.

My rule for large freighters or tankers is four torpedoes, fired on constant bearing, as individual shots. So fire two at middle of target, using the stack for example on freighters as firing bearing, then I fire one at forward mast, one at aft mast. Eve with a small speed error you are likely to get a hit or two which if does not bring down ship immediately can crippled it follow up. Obviously a warships like a carrier or battleship, fire six torpedoes if in a boat so equipped.

Mid sized merchant or tanker, I fire three, one MOT, one forward, one aft.

Smaller freighters, I fire two at MOT or one if am close and confident about speed.

Fire at close range. Fire at 1000 yards or less submerged. 2000-2500 yards on surface.