Just How Accurate Is The Info. In RFB Ship ID Manual?

[Fish40]

I know in RL the info was spotty in some cases, in particular concerning the mastheights of enemy ships. But what about their max. speed? Was this info also sometimes inaccurate, and if so is it reflected in RFB?

The reason I ask is that I tracked a target which turned out to be a Medium Old Tanker. According to a list of "ship lengths" that someone posted over at the UBI forums, as well as the ship ID poster that came with my game, this ship is 113.1m long. I timed the ship crossing the 0 line of the periscope and came up with a speed that was 1k faster than it's listed max speed.

I then used my sonar to get a range. I recorded the distance, and started the clock for three minutes. I then took another reading and used the difference between the two values to get the speed. This time, I came up with 9.4k. This sounded more reasonable, although by eye the ship seemed to be going faster. I plugged this value into the TDC useing the Dick O'kane method of attack.

When the ship crossed the appropriate line of my periscope, I let three fish go (MK14's set to high speed). Useing the camera (can't help it, I like to watch:huh: ) I watched as the three fish sailed just astern of the Tanker. What gives? Obviously despite two methods of calculating, the speed was still off:nope: And yes, the Outer Doors were already open:yep:

So back to the original question: Are the speeds listed accurate? I would guess that since other inaccuracies existed this could be one of them. Don't get me wrong, I love the realistic uncertainty, but I guess we can't take any of the given info as law.

[Webster]

RFB has gone to great lengths to be as accurate and true to historical records as it can be.

if it is recorded somewhere then they use it in RFB

they are very good at finding stuff so i would say you can bet on things being accurate

EDIT: if by some chance you do find an error please let them know and they will take a look

[AVGWarhawk]

LukeFF purchased the ONI manual and used this historical reference for the ingame ONI manual.

[tater]

ONI entries for merchant ships each have a letter rating, A, B, C, D, that let the skippers know how accurate the information was. Even the "A" rated stuff, however was frequently off since the data was as reported to places like Lloyd's. The japanese were not honest in some cases since the ships were actually designed to be commandeered by the IJN in the event of war and pressed into service as AOs, AKs, APs, AVs, etc.

Also, masts and rigging were frequently altered specifically to confuse submarines.

[sckallst]

Holy cow, fish. I could have posted virtually the same thing last night after a run-in with a medium old tanker. I play with no map contacts so it's not especially easy all the time to get good numbers, but I too ran a what I thought was a very good plot and had his speed at 12 kts (one set or readings gave me 13).

Anyway, I finally settled at 11kts, fired a spread of four trying to take her down stern to bow, firing from an AOB of about 105. Only my last torp hit, but nailed her right in the back end and luckily took out the stern and prop. An easy stern shot under the forward mast as she lay dead in teh water took her down after that, but I was wondering myself about my solution on the inital spread.

Wind and sea state were very high, and in hindsight maybe the target picked up a knot (or two) from a tailwind, but I can't be sure. That said, I am pretty sure that you can't trust the manual as gospel, and that's the way it SHOULD be IMO.

[AVGWarhawk]

Agreed! if it was dead nuts accurate and ships did not change speed every now and then, the game would grow boring in about 30 minutes.

[vanjast]

The RFB scope at the moment is 'not accurate' - I think this is being corrected by the RFB team - I've already done it with regard to my RealNav Mod, and waiting to see what RFB come up with.

The game engine/scope has a non-linear Field-Of-View (FOV). So in the vertical or horizontal, the makings are not right, effecting speed (horizontal) and range (vertical mast height) calculations.

I've spent countless 'days' looking at this aspect of the game as it's very important for the accuracy of my Nav Mod - more on this later
:up:

Edt: I'm and ugly 'chief' now... yeahhh!!!

[Fish40]

Thanks for the comments guys. I am in no way complaining about the info in RFB:nope: I love the mod, and it's commitment to realism:yep: I'm sure the info they have is as historicly real as possible. I was just wondering why a ship with a listed max speed of 11kts, could be timed at doing over that? I'm just wondering if the 11kts is accurate:hmm:

It seems another poster had the same kind of run in with the same ship. As far as the accuracy of the scopes in RFB, I'm not sure in this case it would matter. I'm just useing the verticle center line of the scope, and timeing how long the ship takes to cross that line.

[sckallst]

To follow up on that, I did my speed esitmates using my is-was and then again using the in-game 'stopwatch' button after taking a few stadimeter readings. So even with the previously noted optical aberrations aside, I still think that ship was making-better-than-rated speed.

[Fish40]

I may have to agree with you:yep: I saved the game at the initial contact, so I could replay it until I sink the damned thing. I'll try to plug in different speeds, including my initial figure of 12kts, which is faster than the listed max speed.

[LukeFF]

I know in RL the info was spotty in some cases, in particular concerning the mastheights of enemy ships. But what about their max. speed? Was this info also sometimes inaccurate, and if so is it reflected in RFB?
Sadly, this cannot be reflected in RFB. :( If I edited the CFG file to show the "reported" speed of a ship in the recognition manual instead of its "true" speed, then the game will not let the player set it to it's "true" max speed in the Mission Editor. Thus, the max speed one sees in the manual is the ship's true max speed. Trust me, if this problem didn't exist then I would have modded this feature in a long time ago.

[Nisgeis]

The game engine/scope has a non-linear Field-Of-View (FOV). So in the vertical or horizontal, the makings are not right, effecting speed (horizontal) and range (vertical mast height) calculations.

I'll be looking forward to reading what you put. I'm interested in the non=linear part :). I can see how the FOV being wrong would affect your telemeter readings for angular length of target, but the time a target takes to cross the wire for rough speed estimates shouldn't be affected by FOV surely?

[Nisgeis]

[quote=Fish40]If I edited the CFG file to show the "reported" speed of a ship in the recognition manual instead of its "true" speed, then the game will not let the player set it to it's "true" max speed in the Mission Editor.

Have you tried manually editting the mission files to change the speed there?

[Fish40]

[quote by Vanjast]: The game engine/scope has a non-linear Field-Of-View (FOV). So in the vertical or horizontal, the makings are not right, effecting speed (horizontal) and range (vertical mast height) calculations.



I may have read through your response alittle too quickly:oops: I didn't realise that the inaccurate FOV of the scopes would also affect the way a ship's length is represented! Sorry about that. That would certainly explain alot:yep:

[vanjast]

The way around this, is to use the vertical centre-line of the scope as your maker. Placing this at either end of the ship, reading off the bearing at the top.

This 'warped' FOV effect is to 'stretch' the ship as you get closer to the outer edges, making the target longer than what it really is. This makes the range calculations a leelte bit less, if using this method.
http://img.photobucket.com/albums/v297/vanjast/ObsSextant1.jpg

If you examine the vertical scale of the above image, the 0-15 angles (and 45-60) are much larger than the 25-35 degree range, which is in the centre area.
I noticed this as I had to use the whole vertical range to make a sextant, and when directly above I rotated the scope by 90 and noticed the same effect in the horizontal scales.
The sextant has now changed somewhat from this image.
:up:

[Jaeger]

i am looking forward to your nav mod, vanjast. i hope it will find its way to the upcoming gwx4 this time... keep on the work. i would like to see the whole community to work with this mod. than we would have a big discussion about plotting models, tactics and so on... :rock:

[LukeFF]

Have you tried manually editting the mission files to change the speed there?

It could likely be done, yes, but I've not yet tried it.

[Fish40]

Just as a point of interest. Since I saved the game at the initial contact of the target, I had the opportunity to replay the event over and over until I got it right. Here's what happened: All targeting was done useing the Dick O'kane method.


I established the target's course by useing the radar, takeing bearing and range readings at three minute intervals. I closed on the target to establish a visual ID. The target was a Medium Old Tanker. Length=113.1 meters, max listed speed=11knts.

I timed the target crossing the 0 bearing vertical line of my scope. It took 18 seconds to cross the line. This translated to 12knts, which is faster than the listed speed. This too me didn't seem correct, so I tried to use my sonar to establish an initial range, wait three minutes and take range again and deduce speed from there. This time the figure came out to be 9knts, which seemed more reasonable.

I put myself on a 90dgr. course to the target, set up the TDC, and plugged in 9knts as the speed. All 3 torpedoes sailed astern of the target. I replayed the incident useing 10 kts. This time only the first torpedo hit, and well astern.

Trying a third time, and once again timeing the target crossing the 0 line to be sure of myself, I plugged in my initial figure of 12knts. Three Mk14's fired at high speed: The first just forwards of the forward crane, the second amidship, and the third under the stack.

The first torpedo just missed, sailing ahead. The other two struck, close to the AP. The ship did go down bow first about 15 minutes later.

What dose it mean? I don't know. The one thing I didn't try was the ships max speed of 11knts. The reason I didn't was because after two timeings across the 0 line, I came up with the same figure. The ship was in perfect view as well.

[vanjast]

At what speed and bearing, were you travelling towards the target.
This will result in a different speed estimate compared to if you were stationary.
Maybe you didn't take this into account ?
:D

[Fish40]

At what speed and bearing, were you travelling towards the target.
This will result in a different speed estimate compared to if you were stationary.
Maybe you didn't take this into account ?
:D


Good point Vanjast. I make it a point to travel 3kts or less when timeing a target. I also play SH3. I use the OLC GUI mod. I'm sure you're familiar with it. Anyway, the mod has a video tutorial which is superb. In the video, the procedure for timeing a target crossing the 0 line of the scope is explained. The author, (OLC) states that if you're timeing a target across the 0 bearing line, your own speed dose not matter. It's only when you use a line other than the 0 or 180 that you should be moveing very slowly, or stopped altogeather.

I make it a point to use only the 0 or 180 lines, and travel extra slow to be sure.