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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...
@Johnf...if you run a low frequency cd it should transmit enough vibrations to be affective..
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.
Prop sounds, irrespective of frequency are continuous and monotonous, not offering much of interest to fish.
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Topic: Tuning your props to catch more fish (Read 8341 times)
