TMA while moving problems

XLjedi · 07-29-09, 09:26 PM

I think you could make it a little easier on yourself like this...

Let's assume you have the same general TMA track as before. Only this time let's assume the current time is 1520 and the last 3 bearings plotted below are predictions in the future. I've marked the known bearings with diamonds, and circled the predictions.

At 1520 I order the sub to cut the engines and hold position, maybe even order a little reverse engines to bring us to a halt faster.

Notice my predicted bearing for time 1535 is 1°T:236°R

I plotted a contact right on top of my ownship symbol in the center of the MoBo and set the time for the contact as 1520. Then I used the unit advance feature to move the contact ahead to where I would've been at time 1535 had I not remained stationary. Have you used the unit advance feature before? ...it was a tool I added after I wrote the manual and is documented only in the MoBo forum.

Anyway, I know the predicted bearing at time 1535 is 1°T so I can plot that on the contact. And now I sit motionless and wait until 1535.

At 1535 the sonar man reports target bearing 247°R. So I plot the bearing from my stationary location (center of MoBo) and can easily triangulate on the 9000yd distance.

It's also possible to change your course and move to another location for the second reading. I just think it's easier to conceptualize if I tell you to stop the sub.

07-29-09, 09:26 PM	#6
XLjedi Ace of the Deep Join Date: Jun 2005 Location: Palm Beach, Florida Posts: 1,243 Downloads: 53 Uploads: 8	I think you could make it a little easier on yourself like this... Let's assume you have the same general TMA track as before. Only this time let's assume the current time is 1520 and the last 3 bearings plotted below are predictions in the future. I've marked the known bearings with diamonds, and circled the predictions. At 1520 I order the sub to cut the engines and hold position, maybe even order a little reverse engines to bring us to a halt faster. Notice my predicted bearing for time 1535 is 1°T:236°R I plotted a contact right on top of my ownship symbol in the center of the MoBo and set the time for the contact as 1520. Then I used the unit advance feature to move the contact ahead to where I would've been at time 1535 had I not remained stationary. Have you used the unit advance feature before? ...it was a tool I added after I wrote the manual and is documented only in the MoBo forum. Anyway, I know the predicted bearing at time 1535 is 1°T so I can plot that on the contact. And now I sit motionless and wait until 1535. At 1535 the sonar man reports target bearing 247°R. So I plot the bearing from my stationary location (center of MoBo) and can easily triangulate on the 9000yd distance. It's also possible to change your course and move to another location for the second reading. I just think it's easier to conceptualize if I tell you to stop the sub. __________________ Last edited by XLjedi; 07-29-09 at 10:28 PM.