Estimating speed using prop revs.

Telemon · 03-30-12, 01:49 PM

I recently read in a tutorial that it was possible to estimate a vessels speed by counting it's prop revs.
Is there a table or chart to show this anywhere?

bigboywooly · 03-30-12, 01:54 PM

You can try this - for NYGM but may do for you too

http://www.subsim.com/radioroom/showthread.php?t=193770

Apart from that not seen one in a long time

Telemon · 03-31-12, 04:01 AM

Thanks bigboywooly,
Not sure I want to use this method. How would one know if the vessel had three or four bladed props in the first place? But I was intereseted in the technique.

U570 · 03-31-12, 05:26 AM

you can here a change in the sound, like a -whump, whum, whum for a 3 blade, and whump, whum, whum, whum for 4 blades

Canovaro · 04-04-12, 03:00 AM

Look here:

http://subsim.com/radioroom/showthread.php?t=186854

flag4 · 04-04-12, 05:13 AM

Quote:

Originally Posted by Canovaro

Look here:

http://subsim.com/radioroom/showthread.php?t=186854

Canovaro, did you caluclate these times yourself or was it something from the kriegsmarine?

either way its impressive! i wonder how accurate it is as i often listen on hydrophones and try an estimate the speed.

many thanks

Gargamel · 04-08-12, 06:01 PM

Quote:

Originally Posted by U570

you can here a change in the sound, like a -whump, whum, whum for a 3 blade, and whump, whum, whum, whum for 4 blades

I have to laugh at this, in a good way. It reminds me of trying to learn how different diseased lungs sound from a book.

Missing Name · 04-08-12, 08:32 PM

I've toyed with the idea of making "training records" for GWX, along the lines of these databased US sonobuoy/SONAR sessions. (Warning: some racist content against the Japanese, due to the prevalent wartime attitude toward the enemy.) Still a valuable research source despite that.

The records would have probably covered identifying different propulsion types and speed via prop count. However, I scrapped the idea after realizing sound mods and ship adjustments will change the value of such lessons... and I can't speak German for that authentic touch.

03-30-12, 01:49 PM	#1
Telemon Helmsman Join Date: Nov 2008 Posts: 103 Downloads: 288 Uploads: 0	Estimating speed using prop revs. I recently read in a tutorial that it was possible to estimate a vessels speed by counting it's prop revs. Is there a table or chart to show this anywhere?

03-30-12, 01:54 PM	#2
bigboywooly Rear Admiral Join Date: Apr 2006 Location: Swindon, England Posts: 10,151 Downloads: 35 Uploads: 0	You can try this - for NYGM but may do for you too http://www.subsim.com/radioroom/showthread.php?t=193770 Apart from that not seen one in a long time __________________ My mediafire page http://www.mediafire.com/?11eoq19bq9r41

03-31-12, 05:26 AM	#4
U570 Grey Wolf Join Date: Sep 2011 Location: Planet Earth Posts: 867 Downloads: 89 Uploads: 0	you can here a change in the sound, like a -whump, whum, whum for a 3 blade, and whump, whum, whum, whum for 4 blades __________________ "Submariners are a bunch of intelligent misfits that somehow seem to get along, understand each other and work well together"- Anon

04-08-12, 08:32 PM	#8
Missing Name Seasoned Skipper Join Date: Oct 2010 Location: Westun New Yahk Posts: 748 Downloads: 131 Uploads: 0	I've toyed with the idea of making "training records" for GWX, along the lines of these databased US sonobuoy/SONAR sessions. (Warning: some racist content against the Japanese, due to the prevalent wartime attitude toward the enemy.) Still a valuable research source despite that. The records would have probably covered identifying different propulsion types and speed via prop count. However, I scrapped the idea after realizing sound mods and ship adjustments will change the value of such lessons... and I can't speak German for that authentic touch. __________________ Largest target sunk with deck gun: Japanese auxiliary cruiser, 15000 tons Largest engaged: HMS Nelson. Results inconclusive. Read Brag's stuff

03-31-12, 04:01 AM	#3
Telemon Helmsman Join Date: Nov 2008 Posts: 103 Downloads: 288 Uploads: 0	Thanks bigboywooly, Not sure I want to use this method. How would one know if the vessel had three or four bladed props in the first place? But I was intereseted in the technique.

04-04-12, 03:00 AM	#5
Canovaro Ace of the Deep Join Date: Mar 2007 Location: Netherlands Posts: 1,062 Downloads: 34 Uploads: 0	Look here: http://subsim.com/radioroom/showthread.php?t=186854