Lengths of the Merchant ships

ColonelSandersLite · 01-02-13, 04:49 AM

Well, here's the thing. Buddy's interest is measuring relative speed (which is absolute from a dead stop) by timing the time it takes the ship to cross the wire. The fov inaccuracy is irrelevant for his purpose simply because this method measures time, not an angle. It should be noted though that this method is of highly suspect historical accuracy (at least for a submerged sub) as it requires the submarine to be stopped. For reference the formula is:

Target Speed in Knots = 1.944 * ( length in meters / time to cross a bearing in seconds )
or
Target Speed in Knots = 0.592 * ( length in feet / time to cross a bearing in seconds )

Getting accurate measurements without fixing the fov works like this.

As far as measuring a distance, the formula I get from a navy source for a the periscope on high power is Range = 76.2 X Masthead Height or Length (in feet) / Divisions

The part that the FOV issue makes suspect is the constant 76.2. You can come up with a working constant for any combination using some measuring and algebra. For example, supposing we know that a Conte Verde Liner with a length of 570 feet is 5275 yards away and takes up 10 divisions (this is actually what I got using TMO 2.5 with a 1080p res).

Constant to use = 5275 * 10 / 570 = 92.54

So supposing you're running tmo at 1080p, this formula will work for the scope at high zoom (assuming the Conte Verde's length is actually what the game files list):
Range = 92.54 X Masthead Height or Length (in feet) / Divisions

Of course, in that thread (I only skimmed, I must admit) you talk about errors such as the POV not being in the right spot and etc, but this will *only* effect issues where you are actually measuring the target's length in degrees and not where you are measuring the target's transit time afik.

Please feel free to correct me if I'm wrong in any way though.

01-02-13, 04:49 AM	#12
ColonelSandersLite Captain Join Date: Aug 2009 Posts: 481 Downloads: 74 Uploads: 3	Well, here's the thing. Buddy's interest is measuring relative speed (which is absolute from a dead stop) by timing the time it takes the ship to cross the wire. The fov inaccuracy is irrelevant for his purpose simply because this method measures time, not an angle. It should be noted though that this method is of highly suspect historical accuracy (at least for a submerged sub) as it requires the submarine to be stopped. For reference the formula is: Target Speed in Knots = 1.944 * ( length in meters / time to cross a bearing in seconds ) or Target Speed in Knots = 0.592 * ( length in feet / time to cross a bearing in seconds ) Getting accurate measurements without fixing the fov works like this. As far as measuring a distance, the formula I get from a navy source for a the periscope on high power is Range = 76.2 X Masthead Height or Length (in feet) / Divisions The part that the FOV issue makes suspect is the constant 76.2. You can come up with a working constant for any combination using some measuring and algebra. For example, supposing we know that a Conte Verde Liner with a length of 570 feet is 5275 yards away and takes up 10 divisions (this is actually what I got using TMO 2.5 with a 1080p res). Constant to use = 5275 * 10 / 570 = 92.54 So supposing you're running tmo at 1080p, this formula will work for the scope at high zoom (assuming the Conte Verde's length is actually what the game files list): Range = 92.54 X Masthead Height or Length (in feet) / Divisions Of course, in that thread (I only skimmed, I must admit) you talk about errors such as the POV not being in the right spot and etc, but this will only effect issues where you are actually measuring the target's length in degrees and not where you are measuring the target's transit time afik. Please feel free to correct me if I'm wrong in any way though. __________________ My SH4 LP Last edited by ColonelSandersLite; 01-02-13 at 05:00 PM.