SUBSIM Radio Room Forums - View Single Post - manual targeting

kstanb · 09-22-09, 08:17 AM

You need 2 stadimeter reads, you need to send range and bearing to TDC in both cases,and there has to be at least 5 seconds difference to get speed.

My personal preferred method for speed calculation is:

- Start with 2 bearing-range inputs, to get speed and course, most of the times without stopping the boat (I know it can be less accurate, but if he is not closing, it is preferable)

- Position the sub in an intercept course, go to PD and dead stop, if possible, get another 2 bearing-range inputs (this will be more accurate),

- ask the sonarman to keep tracking the target, it is important to notice if he reports any change in speed, if he does, then the solution calculated is already wrong.

- When I am close, I start to get stadimeter ranges and speed*, ideally to confirm the speed I have already calculated. If the sonarman reports a change in speed or something definitively seems to be wrong with the solution and I don't have time to get another 2 bearing-range input, I will probably go with stadimeter based speed

edit: * Just forgot to mention, when calculating speed via stadimeter ranges, you need to calculate many to be sure that you got it right, good thing is it is relatively fast, so getting 5 or 6 measurements in not an issue.
Once you got something like this, at close range, 1st: 10 knots, 2nd: 15knots, 3rd: 10knot, 4th: 9knots, 5th: 11 knots, 6th: 10knots. It will be a safe bet to go with 10 knots.

09-22-09, 08:17 AM	#11
kstanb Sparky Join Date: Mar 2009 Location: Toronto, Canada Posts: 153 Downloads: 105 Uploads: 0	You need 2 stadimeter reads, you need to send range and bearing to TDC in both cases,and there has to be at least 5 seconds difference to get speed. My personal preferred method for speed calculation is: - Start with 2 bearing-range inputs, to get speed and course, most of the times without stopping the boat (I know it can be less accurate, but if he is not closing, it is preferable) - Position the sub in an intercept course, go to PD and dead stop, if possible, get another 2 bearing-range inputs (this will be more accurate), - ask the sonarman to keep tracking the target, it is important to notice if he reports any change in speed, if he does, then the solution calculated is already wrong. - When I am close, I start to get stadimeter ranges and speed, ideally to confirm the speed I have already calculated. If the sonarman reports a change in speed or something definitively seems to be wrong with the solution and I don't have time to get another 2 bearing-range input, I will probably go with stadimeter based speed edit: Just forgot to mention, when calculating speed via stadimeter ranges, you need to calculate many to be sure that you got it right, good thing is it is relatively fast, so getting 5 or 6 measurements in not an issue. Once you got something like this, at close range, 1st: 10 knots, 2nd: 15knots, 3rd: 10knot, 4th: 9knots, 5th: 11 knots, 6th: 10knots. It will be a safe bet to go with 10 knots. Last edited by kstanb; 09-22-09 at 09:12 AM.