Author Topic: Tuning your props to catch more fish (Read 8342 times)

Capt. Hook · « **on:** April 13, 2011, 02:11:43 PM »

Along with my beleif that your boat is the biggest teaser in your spread when trolling, I always run my motors at different rpm and my motors at a different tilt.

In a discussion I had with another person, I have heard that you can tune your props to emmit different frequencies to attract you target species.

Fish have their lateral line connected to their vision and so certain frequencies will attract different species.

I have very little information on the subject but want to investigate more.

Big Eye Tuna - 17hz with tolerance from 14-20hz
Billfish - 32Hz with a tolerance from 28-40Hz
Yellowfin Tuna have a wide range tollerance from 12-48Hz

Does any one have more infomation on the subject, and how would one tune your props to emmit these various frequencies?

Cam Mundy · « **Reply #1 on:** April 13, 2011, 02:14:20 PM »

Pop rivet a whistle to the prop

benniejordaan · « **Reply #2 on:** April 13, 2011, 02:24:32 PM »

Quote from: Cam Mundy on April 13, 2011, 02:14:20 PM

Pop rivet a whistle to the prop

@Mike... I think you are wasting your time and fuel if you are trying to get different frequencies.
I do know of guys who trim one motor up to create more white water.

Where did you get this info from?

Quote from: Fishing Adventures on April 13, 2011, 02:11:43 PM

Big Eye Tuna - 17hz with tolerance from 14-20hz
Billfish - 32Hz with a tolerance from 28-40Hz
Yellowfin Tuna have a wide range tollerance from 12-48Hz

Capt. Hook · « **Reply #3 on:** April 13, 2011, 02:33:11 PM »

I am researching and learning so have very little info Bennie.

I really beleive that there is a lot more in this than we think, and so I am looking for more info, at the moment what I have is sketchy but I think in time I will learn some valuable stuff out of this.

dugong · « **Reply #4 on:** April 13, 2011, 03:04:10 PM »

I rekon rather spend time fine tuning the lures in the spread.

benniejordaan · « **Reply #5 on:** April 13, 2011, 03:43:09 PM »

Quote from: dugongboy on April 13, 2011, 03:04:10 PM

I rekon rather spend time fine tuning the lures in the spread.

X2

Mussel Cracker · « **Reply #6 on:** April 13, 2011, 03:48:13 PM »

I think it could be a very interesting subject to research..keep us updated ..i will see what i can look up

Cam Mundy · « **Reply #7 on:** April 13, 2011, 03:56:05 PM »

Your props are by far the loudest things underwater (any body who has snorkelled will attest to this) the trick will be finding out what the pitch of the props (in Hertz not angle) is at different revs. Add the fact that you have two engines running with two pitches and it can only get more complicated. I can believe mike when he says fish can pick different frequency's sound travels much further and much quicker in water than through air, scientists reckon whale pods used to communicate across entire oceans but all the shipping we have now causes to much interference.

I reckon make an underwater speaker and play them some Zeppelin

Mussel Cracker · « **Reply #8 on:** April 13, 2011, 04:07:45 PM »

check this out..
http://icob.sinica.edu.tw/ICOBUserfile/yanweb/publication/fulltxt/Boat_noise_16.pdf

benniejordaan · « **Reply #9 on:** April 13, 2011, 04:13:10 PM »

Here is a question...
When you trim your motor up is it changing the frequency of the sound or do you just hear it differently because the exhaust is closer to the surface and being less muffled?

Capt. Hook · « **Reply #10 on:** April 13, 2011, 04:21:46 PM »

Quote from: benniejordaan on April 13, 2011, 04:13:10 PM

Here is a question...
When you trim your motor up is it changing the frequency of the sound or do you just hear it differently because the exhaust is closer to the surface and being less muffled?

These are all the things we want to find out...

John F · « **Reply #11 on:** April 13, 2011, 07:44:14 PM »

Thanks for raising this issue FA... this is something I also find very interesting and I've been researching about it for some time now...

There are actually very few studies done on sound effects on large pelagic predators.... except maybe for sharks...

Well, it is known for a long time that fish are not mute (e.g. reef fishes have been shown to make low frequency sounds when spawning) and of course injured fish do make low frequency sounds... no wonder sharks hear (and are more attracted to) sounds in frequencies between 10 and 800 Hz (while humans hear sounds between 20 - 20,000 Hz)... but note that they do not respond to continuous sounds even in low frequencies...

It is also interesting to read that some old timers swear by the old diesel inboards as

attractors.... maybe its the low frequency sounds generated by the motors...

A study in the late 70's found a negative correlation between catch rates and sound frequencies higher that 1500 Hz (produced by boats fishing for albacore)

My take is that predators are suckers for easy food... if one can simulate injured fish (by producing low frequencies all around - remember these can be detected by a shark underwater up to 250 m from the source!), one will be attracting lot's of predators (including sharks!)...

I'm currently installing on my boat (and will shortly be experimenting) a "sound producing device" specifically designed to attract predators in the +200 m line

... at this stage it is still a "secret"...

Capt. Hook · « **Reply #12 on:** April 13, 2011, 07:55:05 PM »

Quote from: John F on April 13, 2011, 07:44:14 PM

Thanks for raising this issue FA... this is something I also find very interesting and I've been researching about it for some time now...

There are actually very few studies done on sound effects on large pelagic predators.... except maybe for sharks...

Well, it is known for a long time that fish are not mute (e.g. reef fishes have been shown to make low frequency sounds when spawning) and of course injured fish do make low frequency sounds... no wonder sharks hear (and are more attracted to) sounds in frequencies between 10 and 800 Hz (while humans hear sounds between 20 - 20,000 Hz)... but note that they do not respond to continuous sounds even in low frequencies...

It is also interesting to read that some old timers swear by the old diesel inboards as attractors.... maybe its the low frequency sounds generated by the motors...

A study in the late 70's found a negative correlation between catch rates and sound frequencies higher that 1500 Hz (produced by boats fishing for albacore)

My take is that predators are suckers for easy food... if one can simulate injured fish (by producing low frequencies all around - remember these can be detected by a shark underwater up to 250 m from the source!), one will be attracting lot's of predators (including sharks!)...

I'm currently installing on my boat (and will shortly be experimenting) a "sound producing device" specifically designed to attract predators in the +200 m line ... at this stage it is still a "secret"...

Can you find any info on which species work in different frequencies like the few I mentioned..

Rory mundy · « **Reply #13 on:** April 13, 2011, 09:15:52 PM »

so what does the frequency of our transducer do? I believe we spend to much time being tecnical rather than just enjoying our fishing

John F · « **Reply #14 on:** April 13, 2011, 10:38:11 PM »

Well, sound to be perceived need to have both the right frequency (Hz) and pressure level - SPL (dB) of the perceiving hear...

In the case of most fish, as stated before, their frequency is between 10-800 Hz and a SPL of 80-120 dB re: 1 microPa...

Most transducers have the "wrong" frequency 50-200 kHz and the wrong SPL (-10 dB)... fish can't hear past 1500 Hz ....

We can hardly hear the clicks of the transducer as well... we have the "right" frequency but the SPL ("volume" - if I can use the word) is wrong ...

Does it make sense?!

PH · « **Reply #15 on:** April 14, 2011, 05:35:51 AM »

Would it not be easier to introduce a "sound producing device" inside the lures?.
This can be activated by the force of the water rushing past the lure and could be of similar
frequency generated by bait fish being chased?
I've been thinking about ways to produce a string of air bubbles but sound would be better.

benniejordaan · « **Reply #16 on:** April 14, 2011, 07:10:21 AM »

Right off the bat there is a problem....
When you talk about the frequency fish hear you talk about Hz.

In that article posted by Mussel Cracker they say a 55HP motor produces 1,3 kHz. Kilo = 1000 therefore 1300 Hz at idle. We don't troll at idle!! It is way above anything you posted above. - 12-48Hz, in fact 27 X too high.

John mentioned, anything above 1500 Hz has a negative effect!

OK, so now lets assume we know we want 12-48 Hz (info given to us by Mike). How are you going to get your engine to produce this especially knowing it is going to be closer to 1500Hz.

Personally, I think you are trying to be too technical and wasting fuel at the same time!

@ John, what would be the point in making beautiful music and have heavy metal playing at the same time?? In your case a music box for fish plus 2 noisy outboards?

@ PH, the frequency you are looking for is supposed to be produced by that little thing Lowrance sells, we had a poll some time ago and voted it's a load of junk and doesn't work!

1309sg · « **Reply #17 on:** April 14, 2011, 07:49:32 AM »

Just a quick note here. Different boat/engine combinations produce different reactions from mullet in estuaries/ rivers. I've experienced this firsthand on many occasions when specifically trying to raise mullet. I had a duck with a blueprinted 40 and a speedboat with a 90 Merc. At the same speeds the duck got the mullet to jump out the water, sometimes even onto the boat. Not with the speedboat, not at the same revs/speed.

I think FA has a point here, although my guess would be that vibration and disturbance created would be the factors and not necessarily sound?

my 2c

John F · « **Reply #18 on:** April 14, 2011, 07:58:12 AM »

Bennie, you have valid points there...

I don't think it is feasible to get low frequency sounds from the outboards... unless one modifies it so much at the risk of turning it into a low-frequency sound producing junk!!!!

What I'm trying to get is a device that will play low frequency sounds... it will deliver the sound from a concealed position in the boat that even if it was music I would not hear it...

The ocean is not "silent".... lot's of noises there... my idea is to have the "right" sounds around my boat...

Prego · « **Reply #19 on:** April 14, 2011, 08:35:48 AM »

Try this

could'nt resist.