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OFFSHORE ANGLING => General Offshore Angling Discussion => Topic started by: Capt. Hook on April 13, 2011, 02:11:43 PM
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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?
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Pop rivet a whistle to the prop
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Pop rivet a whistle to the prop
:hyst: :hyst: :hyst:
@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?
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
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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.
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I rekon rather spend time fine tuning the lures in the spread.
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I rekon rather spend time fine tuning the lures in the spread.
X2
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I think it could be a very interesting subject to research..keep us updated ..i will see what i can look up
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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
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check this out..
http://icob.sinica.edu.tw/ICOBUserfile/yanweb/publication/fulltxt/Boat_noise_16.pdf (http://icob.sinica.edu.tw/ICOBUserfile/yanweb/publication/fulltxt/Boat_noise_16.pdf)
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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?
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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...
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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 :billf: 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 :hnthnt: ... at this stage it is still a "secret"...
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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 :billf: 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 :hnthnt: ... 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..
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so what does the frequency of our transducer do? I believe we spend to much time being tecnical rather than just enjoying our fishing
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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?!
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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.
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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!
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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 :dunno:
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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...
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Try this :vio
sry could'nt resist.
:crzy
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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...
Play them some celine dion they will probably jump on the boat to get away
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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...
Installing a Hifi on your boat is completely different to "tuning your props to play the right tunes"! As for the latter, I believe you are wasting your time and fuel! What trimming your motor up will do is create more white water which I think is an attractor.
As for a Hifi... sounds like more maintenance and I already have enough of that. More maintenance means less time on the water which means less fish any way!
The benefit must out weigh the cost. If it doesn't, it's not worth doing!
I say just fish more! You want better quality fish, swim bigger lures! You want more fish, swim smaller lures! I agree with dugongboy, if you want fish make sure your lures are tuned right and swimming right at all times!
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Bennie, you know me... it's not gonna be HI FI... it will be low, very low fi... hehehehe
I agree: more time in the water = more fish...
I'm trying to get a very low-maintenance set up.... cheap and low tech... if it works: yeah... if it doesn't... oh well.... I just like to play around with toys...
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@Johnf...if you run a low frequency cd it should transmit enough vibrations to be affective..
@ Bennie ..it still makes interesting conversation..and hopefully one day something comes of it...
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@Johnf...if you run a low frequency cd it should transmit enough vibrations to be affective..
:corrct: :creep:
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There was an article in the ski boat mag a few years ago which covered this in great detail, I will try find it when I get back.
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There are companies in the US that specialise in tuning props to catch fish, on tournamant boats that do well they never ever touch the props if teh boat is producing. All though this is for Sport Fishers with in boards, I am 100% convinced that it will apply to out boards also.
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Sound travels 4.5 – 5 times faster in water (1500m/s!) than in air, the speed being influenced by temperature, salinity and pressure (depth). Because of this, fish can detect sound over a far greater distance than chemical or visual stimuli. Sound waves in water generate both particle displacement (Near-field) and pressure changes (Far-Field) and thus “carries” more information than in air. Fish have various adaptations to pick up and process sound waves, and this can differ significantly from species to species. Fish may have internal ears, accessory auditory organs, lateral lines or a combination of these. Often fish with swim-bladders will use the bladder as a type of amplifier to increase sensitivity to sounds. Fish use sounds to communicate, find prey, confuse prey, or detect predators and other dangers.
Boat motors produces a variety of noises, of which prop-noise is the most important in the underwater world as it transmits its sound directly into the water. The propeller creates pressure pulses as the blades rotate, and the rate of rotation will determine the frequency of these. The most significant source of prop noise comes from cavitation which is the formation of bubbles when the negative pressures created by the blades drop below the vapor pressure of the water. As these bubbles collapses, it creates shock waves. The principle of cavitation and the resultant shock wave is used by pistol and mantis shrimps to stun their prey.
I believe that different fish will react differently to prop sounds, but that this sound would probably not be an attraction to the fish. Fish are often adapted to pick up small variations in pressure and water movements as is produced by other fish and are adapted to pick these up in spite of the plethora of other sounds in the ocean environment. Prop sounds, irrespective of frequency are continuous and monotonous, not offering much of interest to fish.
There may be other factors at play with the idea of changing pitches etc to change frequency. If it reduces cavitation, the prop will immediately be quieter and will produce less shock waves. I am not sure if changing the pitch etc will change the frequency significantly, and studies have shown fish conditioned to aggregate for receiving food at for instance 300Hz, will also react to frequencies of between 200Hz an 800Hz, which may indicate that fish don’t rely on frequency per-se. While on the subject of conditioning… in heavily fished areas, fish may be conditioned to associate prop noise with danger, which is one of the reasons why paddle ski and jet-ski fisherman may be having good success. On the other hand, in areas where heavy chumming takes place, fish my be conditioned to the fact that the prop noise “brings food”, and they may actually follow the noise in the hope of a free meal.
I still think it is a fascinating topic, and that there is still too many gaps in our knowledge to make conclusive deductions. Like many other fishing tricks, if it is something that is going to give you more confidence, than it may just work for you! Well, that’s my 2c.
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Very interesting and scientific explanation, Andre!
I always wondered why props produce air bubbles when there is no "air" in the water :nuts:
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i agree with you critter....i think there is still so much we dont know....but over time and comments like your and others i think something will come of this...
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Sound travels 4.5 – 5 times faster in water (1500m/s!) than in air, the speed being influenced by temperature, salinity and pressure (depth). Because of this, fish can detect sound over a far greater distance than chemical or visual stimuli. Sound waves in water generate both particle displacement (Near-field) and pressure changes (Far-Field) and thus “carries” more information than in air. Fish have various adaptations to pick up and process sound waves, and this can differ significantly from species to species. Fish may have internal ears, accessory auditory organs, lateral lines or a combination of these. Often fish with swim-bladders will use the bladder as a type of amplifier to increase sensitivity to sounds. Fish use sounds to communicate, find prey, confuse prey, or detect predators and other dangers.
Boat motors produces a variety of noises, of which prop-noise is the most important in the underwater world as it transmits its sound directly into the water. The propeller creates pressure pulses as the blades rotate, and the rate of rotation will determine the frequency of these. The most significant source of prop noise comes from cavitation which is the formation of bubbles when the negative pressures created by the blades drop below the vapor pressure of the water. As these bubbles collapses, it creates shock waves. The principle of cavitation and the resultant shock wave is used by pistol and mantis shrimps to stun their prey.
I believe that different fish will react differently to prop sounds, but that this sound would probably not be an attraction to the fish. Fish are often adapted to pick up small variations in pressure and water movements as is produced by other fish and are adapted to pick these up in spite of the plethora of other sounds in the ocean environment. Prop sounds, irrespective of frequency are continuous and monotonous, not offering much of interest to fish.
There may be other factors at play with the idea of changing pitches etc to change frequency. If it reduces cavitation, the prop will immediately be quieter and will produce less shock waves. I am not sure if changing the pitch etc will change the frequency significantly, and studies have shown fish conditioned to aggregate for receiving food at for instance 300Hz, will also react to frequencies of between 200Hz an 800Hz, which may indicate that fish don’t rely on frequency per-se. While on the subject of conditioning… in heavily fished areas, fish may be conditioned to associate prop noise with danger, which is one of the reasons why paddle ski and jet-ski fisherman may be having good success. On the other hand, in areas where heavy chumming takes place, fish my be conditioned to the fact that the prop noise “brings food”, and they may actually follow the noise in the hope of a free meal.
I still think it is a fascinating topic, and that there is still too many gaps in our knowledge to make conclusive deductions. Like many other fishing tricks, if it is something that is going to give you more confidence, than it may just work for you! Well, that’s my 2c.
Thanks bud.
So much to lern still.
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Prop sounds, irrespective of frequency are continuous and monotonous, not offering much of interest to fish.
This sounds like I am stating it as a fact, whereas it is my oppinion.... I meant to say that prop sound probably does not offer much if interest to fish.