How do I determine speed with stopwatch?

[JochenHeiden]

I've been trying real hard following manual's instructions for determining the speed of a ship.

I open the data tool, and click on the speed button in lower right corner. The manual says to simply click left click the stopwatch button, let it wait, then left click again and you'll get data. I do this... and I get nothing.

My realism settings are realistic, I have to find all data and enter into TDC manually. I am having a bad time trying to find out the speeds.


Using RFB 1.24 and patch 1.2 Help please!

[RocketDog]

Unfortunately the stopwatch does not work. This may be fixed in the next patch. I hope so. In the meantime we have to either calculate the speed from repeated observations or make an estimate based on bow-wave etc.

Cheers,

RD.

[JochenHeiden]

This game was released with so many bugs not even a double-shot of pennicilin will save it. Outrageous.

[joea]

No, it is really easy, start the watch and see how long it takes the target to cross your periscope...you know the length from the manual and can thus calculate it. Or using map contacts on, use the "3 minute" rule you can search on this forum for both methods.

[daft]

I usually just set the speed to half of what the target can do and go from there. If I miss I simply "re-guesstimate" the speed and so far I've been pretty successful using this method. I hate math. :)

[AVGWarhawk]

Draft and Joea have two excellent methods. I'm more of a guesstimater like Draft. I use about half of the total speed the vessel can do but I get in close and dirty so if I'm off by a kt or two, it does not matter. Even with this said, I find it harder to guess in SH4 than SH3. To me, 7kts was about the most correct figure for every vessel in SH3. SH4, there is a wide range of speeds for each encounter and each vessel. Much more of a challenge.

At any rate, the chronometer is on top of the bug list that needs to be corrected. For now, guess or use Joea method mentioned and, if you get a message the convoy is doing X kts...usually they are so set you speed for what the message stated.

[rulle34]

Will it be a 1.3 patch?? Any news on that?

[WernerSobe]

look here http://www.subsim.com/radioroom/showthread.php?t=112448 (http://www.subsim.com/radioroom/showthread.php?t=112448&highlight=easy+fast+speed)

[jhelix70]

I use the map contact, mark with the pencil tool, start the stopwatch and mark again after 6 minutes. Then measure with the ruler tool. A ship travelling at 10kts will go 1 nm in 6 minutes, so the math is easy!

[rdtwendt]

Aside from using the actual trigonometry to setup the entire firing solution, which is not hard mind you, one easy method to calculate the speed is by making an intelligent guess (as discussed before with bow-wave or half of the listed reference speed) and entering this data into the position keeper. If your range and AOB estimates are reasonably good, then you can compare the relative bearing of your locked periscope as it tracks the target to the relative bearing your position keeper is telling you the target should be based on the speed, range, and AOB you entered. Let's say the PK says the target is at 55 deg, when your locked periscope clearly sees the ship at 52 degrees. If the target was travelling such that the relative bearing should be increasing (i.e. 0-->90) then this would be an indication that your PK has him travelling too fast, and you should dial down the speed estimate and try again. Once you can make a couple of successive checks where the periscope relative bearing matches what the PK bearing is predicting, you know you have a decent solution and should feel comfortable expending one of your torpedoes.

As mentioned earlier, the actual trigonometry that the chronometer feature would be using (if it woked properly) is not hard to derive and calculate, and can be used for more exact initial guesses. Regardless of the situation, it is always a good idea to compare your firing solution via the PK with actual target observations from the periscope and hydrophone before engaging. The PK was a huge advantage for US subs and I rely on it quite heavily on my patrols.