Estimating speed in less than 1min.

Tonnage_Ace · 10-15-09, 01:52 PM

Just started playing SH3 again and I forget the method I used to quickly judge speed peering through the scope.

I used to get a rough heading of the target ship/convoy along with a rough speed est. but I fine tuned it with this speed calculation where I would sit off the ship's expected path at 90* and time how long it took the ship to cross my vertical reticule. This should be REALLY helpful for any newbies because your range and AOB can be off but speed is the killer. If the ship passes your reticule at 340* you can get a good speed estimate for the -5/+5 gyro shot.

Anyone remember that formula? I used to tap it into my phone from memory

I know the values were ship's length, time, ???, speed in knots.

Picked up a new toy, Germans make good cars too

psykopatsak · 10-15-09, 02:54 PM

HAH, God 'ole "Spit-log" from a distance? never thought of that!

the spitlog formula is (2xboat length in meters)/(time in seconds)=speed in knots. the time is that for a stationary object in the water to go from very boats prow to stern.

if you have a calculator you could use 1.852 x boat length instead.

10-30-09, 07:37 PM

Quote:

Originally Posted by psykopatsak

HAH, God 'ole "Spit-log" from a distance? never thought of that!

the spitlog formula is (2xboat length in meters)/(time in seconds)=speed in knots. the time is that for a stationary object in the water to go from very boats prow to stern.

if you have a calculator you could use 1.852 x boat length instead.

Thanks psykopatsak!
This should greatly improve my ability to gather information while submerged.
As I'm into oktober 1943, spending too much time on the surface is not a good idé.

psykopatsak · 10-31-09, 11:22 AM

now, the odd thing i have herd is that you should mutliply with 1.94? why is that?

Sonoboy · 10-31-09, 11:47 AM

the way you come to multiply by 1.94 is as follows:

speed in knots = (length in meters)/(time in seconds)*(3600 to convert seconds to hours)/(1000 to convert meters to kilometers)*(0.54 to convert kilometers to nautical miles)

if you simplify it, it becomes:

speed in knots = (length in meters)/(time in seconds)*1.944

Pisces · 10-31-09, 05:54 PM

We want the speed to be in knots, or nautical miles per hour. But we have only the distance in meters, and the time in seconds, so it needs some conversion factors.

ship length in nautical miles= length/1852m

time in hours = time in seconds/3600s

Speed = length /time

Code:

Speed (in knots, nautical miles/hour) = length         seconds
                                        --------  / -------------
                                           1852          3600

Speed (in knots, nautical miles/hour) = length       3600
                                          -------  * --------
                                          1852        seconds

Speed (in knots, nautical miles/hour)  = (3600/1852) * length/seconds

3600/1852 = 1.94...

psykopatsak · 10-31-09, 06:59 PM

oh, yeah, that explains how. advanced math :/

10-15-09, 01:52 PM	#1
Tonnage_Ace XO Join Date: Jan 2006 Location: Vancouver Posts: 411 Downloads: 5 Uploads: 0	Estimating speed in less than 1min. Just started playing SH3 again and I forget the method I used to quickly judge speed peering through the scope. I used to get a rough heading of the target ship/convoy along with a rough speed est. but I fine tuned it with this speed calculation where I would sit off the ship's expected path at 90* and time how long it took the ship to cross my vertical reticule. This should be REALLY helpful for any newbies because your range and AOB can be off but speed is the killer. If the ship passes your reticule at 340* you can get a good speed estimate for the -5/+5 gyro shot. Anyone remember that formula? I used to tap it into my phone from memory I know the values were ship's length, time, ???, speed in knots. Picked up a new toy, Germans make good cars too

10-31-09, 05:54 PM	#6
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,892 Downloads: 300 Uploads: 0	We want the speed to be in knots, or nautical miles per hour. But we have only the distance in meters, and the time in seconds, so it needs some conversion factors. ship length in nautical miles= length/1852m time in hours = time in seconds/3600s Speed = length /time Code: Speed (in knots, nautical miles/hour) = length seconds -------- / ------------- 1852 3600 Speed (in knots, nautical miles/hour) = length 3600 ------- * -------- 1852 seconds Speed (in knots, nautical miles/hour) = (3600/1852) * length/seconds 3600/1852 = 1.94... __________________ My site downloads: https://ricojansen.nl/downloads Last edited by Pisces; 10-31-09 at 10:06 PM.

10-15-09, 02:54 PM	#2
psykopatsak Medic Join Date: Oct 2009 Location: Grid AO27 Posts: 161 Downloads: 27 Uploads: 0	HAH, God 'ole "Spit-log" from a distance? never thought of that! the spitlog formula is (2xboat length in meters)/(time in seconds)=speed in knots. the time is that for a stationary object in the water to go from very boats prow to stern. if you have a calculator you could use 1.852 x boat length instead.

10-31-09, 11:22 AM	#4
psykopatsak Medic Join Date: Oct 2009 Location: Grid AO27 Posts: 161 Downloads: 27 Uploads: 0	now, the odd thing i have herd is that you should mutliply with 1.94? why is that?

10-31-09, 11:47 AM	#5
Sonoboy Planesman Join Date: Aug 2005 Location: United States, CA Posts: 195 Downloads: 8 Uploads: 0	the way you come to multiply by 1.94 is as follows: speed in knots = (length in meters)/(time in seconds)(3600 to convert seconds to hours)/(1000 to convert meters to kilometers)(0.54 to convert kilometers to nautical miles) if you simplify it, it becomes: speed in knots = (length in meters)/(time in seconds)*1.944

10-31-09, 06:59 PM	#7
psykopatsak Medic Join Date: Oct 2009 Location: Grid AO27 Posts: 161 Downloads: 27 Uploads: 0	oh, yeah, that explains how. advanced math :/