Engine RPMs and hydrophone speed calculation question

commandosolo2009 · 02-02-11, 11:18 AM

Hello skippers!

Today, I decided to convert to the much acclaimed, old-styled, sonar only attack. Now, in order to get speed for the target, with contacts on, I'd start a 10 minute monitor over the PPI and divide the range covered from start time to stop time, then do the regular maths distance/time to get his speed. Now comes the submerged problem as an arbitrary estimate is usually the case, and you end up with off the chart calculations and many misses...

Now, I wanted to ask if there was a RPM guide around here, much like RPM over speed in kts?, for trained ears to use.. I kinda like the idea of staying low and not exposing myself at all, and this is what I also hope to get your advice on.

To be exact, is there a chart or not necessarily a chart, but a rule for rpms vs speed (kts) here? And, if I put my hydrophone operator on monitor, he leaves all the targets and focuses on the warships which are naturally ahead of the convoy, so is there a way to let him monitor that specific screw on the telegraph? I guess there aint, but I'm just spitballing here..

Another thing, if he were to monitor a sole merchant, should I set the TDCPK to this bearing or do a fan spread ahead of the target?

Does anyone know the actual grading on scope, corresponding to the spread dial, meaning which periscope mark on the horizontal line corresponds to say, 5 clicks left spread?

And if someone could help me with this periscope? I cant find the markings anywhere here, and certainly its not websters mod.

Here, I want these extra periscope bearing marks:

So, do you guys know this?
Thanks

02-02-11, 11:18 AM	#1
commandosolo2009 Grey Wolf Join Date: Sep 2009 Location: Egypt Posts: 840 Downloads: 132 Uploads: 0	Engine RPMs and hydrophone speed calculation question Hello skippers! Today, I decided to convert to the much acclaimed, old-styled, sonar only attack. Now, in order to get speed for the target, with contacts on, I'd start a 10 minute monitor over the PPI and divide the range covered from start time to stop time, then do the regular maths distance/time to get his speed. Now comes the submerged problem as an arbitrary estimate is usually the case, and you end up with off the chart calculations and many misses... Now, I wanted to ask if there was a RPM guide around here, much like RPM over speed in kts?, for trained ears to use.. I kinda like the idea of staying low and not exposing myself at all, and this is what I also hope to get your advice on. To be exact, is there a chart or not necessarily a chart, but a rule for rpms vs speed (kts) here? And, if I put my hydrophone operator on monitor, he leaves all the targets and focuses on the warships which are naturally ahead of the convoy, so is there a way to let him monitor that specific screw on the telegraph? I guess there aint, but I'm just spitballing here.. Another thing, if he were to monitor a sole merchant, should I set the TDCPK to this bearing or do a fan spread ahead of the target? Does anyone know the actual grading on scope, corresponding to the spread dial, meaning which periscope mark on the horizontal line corresponds to say, 5 clicks left spread? And if someone could help me with this periscope? I cant find the markings anywhere here, and certainly its not websters mod. Here, I want these extra periscope bearing marks: So, do you guys know this? Thanks __________________ x.com/lexatnews