Hydrophone Distance Estimation

ChrisPhoenix · 10-03-19, 08:53 AM

Greetings fellow Kaleuns!

I am trying to become a better hydrophone operator. So i was wondering if there is any "rule of thumb" or anything like "a gain of 3 means around 5000m". Basically i am looking for a quick but simple way to estimate the distance to the target as accurate as possible but in the shortest amound of time. Methods like the four bearings-method are never used in our missions. So maybe you guys can help me out with your experience?

thanks in advance!

Chris Phoenix

Pisces · 10-03-19, 09:25 AM

You might want to search the WP discord server. There have been plenty rules of thumb postulated for that. But the problem is, different unit might have different source levels. So you might think X gain is Y far, but it could actually be further or closer. That's why I don't bother. It's also not that neccesary. Just point the bow at the sound and go full speed on the surface. They will appear soon enough out of the mist.

Superesse · 10-04-19, 12:04 AM

Regarding steaming towards the convoy and finally they appear. Doesn’t that only work in clear weather or slightly cloudy (I don’t remember the terms)? If it’s foggy you cannot do that, right? Because you won’t see the convoy until you’re dangerously close? I’ve never tried fog yet, so it’s just a guess.

About distance checking. I am poor at it myself. But I think you need to be close enough to distinguish a single ship, then count the propeller rotational speed (because I assume that affects sound level?) and then based on the combination of gain and propeller speed calculate the distance (I don’t know how). This is only my guess.

Lost At Sea · 10-04-19, 12:45 AM

I would also love to know how to do that!
By the time I managed to fumble my way through the four bearings-method the convoy has usually reached Rio de Janeiro...

Cheers,
Lost

ChrisPhoenix · 10-04-19, 03:10 AM

The Discord Channel is a little messy in terms of finding information in my opinion. I rejoined it, read thourgh some stuff but hard to find anything. There is just too much going on.

Just heading towards the convoy is fine for the most situations sure, but i would also like to be able to know if a destroyer is at safe distance to surface by just relying on the hydrophone for example.

Of course i don't want to say "alright contact is exactly 5435m away." But plus or minus a 1000 meters would be nice to know.

Pisces · 10-04-19, 05:32 AM

It should be safe if you do a periscope check before you surface. Should be standard procedure anyway.

Yes, discord is messy. But you should be able to search the channels for keywords. Rule seems to fit as one.

10-03-19, 08:53 AM	#1
ChrisPhoenix Bosun Join Date: Feb 2019 Posts: 62 Downloads: 7 Uploads: 0	Hydrophone Distance Estimation Greetings fellow Kaleuns! I am trying to become a better hydrophone operator. So i was wondering if there is any "rule of thumb" or anything like "a gain of 3 means around 5000m". Basically i am looking for a quick but simple way to estimate the distance to the target as accurate as possible but in the shortest amound of time. Methods like the four bearings-method are never used in our missions. So maybe you guys can help me out with your experience? thanks in advance! Chris Phoenix

10-03-19, 09:25 AM	#2
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,894 Downloads: 304 Uploads: 0	You might want to search the WP discord server. There have been plenty rules of thumb postulated for that. But the problem is, different unit might have different source levels. So you might think X gain is Y far, but it could actually be further or closer. That's why I don't bother. It's also not that neccesary. Just point the bow at the sound and go full speed on the surface. They will appear soon enough out of the mist. __________________ My site downloads: https://ricojansen.nl/downloads

10-04-19, 05:32 AM	#6
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,894 Downloads: 304 Uploads: 0	It should be safe if you do a periscope check before you surface. Should be standard procedure anyway. Yes, discord is messy. But you should be able to search the channels for keywords. Rule seems to fit as one. __________________ My site downloads: https://ricojansen.nl/downloads

10-04-19, 12:04 AM	#3
Superesse Seaman Join Date: May 2019 Posts: 34 Downloads: 1 Uploads: 0	Regarding steaming towards the convoy and finally they appear. Doesn’t that only work in clear weather or slightly cloudy (I don’t remember the terms)? If it’s foggy you cannot do that, right? Because you won’t see the convoy until you’re dangerously close? I’ve never tried fog yet, so it’s just a guess. About distance checking. I am poor at it myself. But I think you need to be close enough to distinguish a single ship, then count the propeller rotational speed (because I assume that affects sound level?) and then based on the combination of gain and propeller speed calculate the distance (I don’t know how). This is only my guess.

10-04-19, 12:45 AM	#4
Lost At Sea Electrician's Mate Join Date: May 2004 Posts: 136 Downloads: 94 Uploads: 0	I would also love to know how to do that! By the time I managed to fumble my way through the four bearings-method the convoy has usually reached Rio de Janeiro... Cheers, Lost

10-04-19, 03:10 AM	#5
ChrisPhoenix Bosun Join Date: Feb 2019 Posts: 62 Downloads: 7 Uploads: 0	The Discord Channel is a little messy in terms of finding information in my opinion. I rejoined it, read thourgh some stuff but hard to find anything. There is just too much going on. Just heading towards the convoy is fine for the most situations sure, but i would also like to be able to know if a destroyer is at safe distance to surface by just relying on the hydrophone for example. Of course i don't want to say "alright contact is exactly 5435m away." But plus or minus a 1000 meters would be nice to know.