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Author Topic:   Quiet Outboard: Effect on Fish

BOB KEMMLER JR posted 07-18-2006 12:16 AM ET (US)
With all the hype over quiet outboards lately, I wondered where does the noise go? If it is so quiet above the water, does this mean the noise gets pumped below the water's surface? If so what effect does this have for fishing areas like shallow grass flats where noise is a big no-no? Sure you can pole or run a electric trolling motor, but just how close can you get with your main motor before it spooks the fish?
jimh posted 07-18-2006 12:24 AM ET (US)
Even an older outboard motor, considered to be a loud motor by today's standards, was directing most of the sound of its operation into the water. The modern outboard which seems quiet to the operator is probably just as loud and likely louder to the fish.
I was standing next to a 150-HP E-TEC which was running on an ear-muff style water hose adapter and an open-air exhaust. The technician gave the motor a quick shot of throttle advance. Without the immersion of the exhaust in the water, the sound level from the motor was extremely loud, and I literally jumped backwards from the shock of it as the motor revved up to a couple of thousand RPM. Yet, this same motor, when in the water and running at that same speed, was the quietest of all 150-HP motors tested in a recent "shootout." It was still producing all that sound, but in this case almost all of the sound is being directed out the underwater exhaust.
BOB KEMMLER JR posted 07-18-2006 12:52 AM ET (US)
I don't know why it posted double Jim?Yea i realize that most of the noise gets directed under the water(except some of the offshore dump type mids)but if it's noiser above the water,I'd have to think it's a little quieter under the water.i know some fish are attracted to the drone of diesels,or so it's said,but a lot of fish head for the hills when something noisy(to them)heads thier way.
Chuck Tribolet posted 07-18-2006 01:04 AM ET (US)
Having been on the bottom and heard a lot of boats go over --
they are ALL noisy. I think it's more prop noise than
exhaust.

Chuck
Perry posted 07-18-2006 02:38 AM ET (US)
When my neighbor, who lives 5 houses away, runs his classic 140 HP 2 stroke on the ear muffs at idle, I can here it in my living room. With my 135 HP 4 stroke running at idle on the ear muffs, I can't hear it 20 feet away.
Teak Oil posted 07-18-2006 05:33 PM ET (US)
When you are swimming and there are boats a couple hundred yards away on plane, go underwater and you will hear how loud the prop is in the water. It goes a LONG ways. This sound is much more significant than the exhaust
Binkie posted 07-19-2006 07:10 PM ET (US)
Sound must be the reason commercial fishermen seldom run Mercs, don`tcha think?
ratherwhalering posted 07-20-2006 01:34 AM ET (US)
I knew it! I am a good fisherman...it's just that darn quiet E-TEC scaring all the fish away. Now I can stop blaming he electrical field created by the engine every time I get skunked!
HAPPYJIM posted 07-20-2006 07:02 AM ET (US)
Noise can't be that much of a bother for them if trolling catches so many fish. Fish like barley and hops.....what better way to lure them in than a cooler full of cold ones!
Alex K posted 07-20-2006 07:42 AM ET (US)
Many dutch fishermen troll jerkbaits for northern pike and Zander (europ. walleye) in the many kilometers of very narrow and shallow canals they have. They catch fish in the bubble trail of their outboards. The canals are sometimes not deeper than 3-5 feet. So I don't think an outboard will spook fish if they're used to it.
Alex
BOB KEMMLER JR posted 07-20-2006 11:55 AM ET (US)
Alex-Try motoring onto a flat and then try to count the redfish that are blazing away from you lol
CUOffshore posted 07-20-2006 04:27 PM ET (US)
Don't assume that noise is a bad thing. Your boat is the best "teaser" around. Noise can be a very powerful fish attractant. Some hull/engine combinations "raise fish" better than others, especially when trolling offshore.
-Dave
Binkie posted 07-20-2006 05:40 PM ET (US)
back in the `70s in SW Florida, the commercial seatrout fishermen, would use a 14 ft. wooden skiff (rowboat) powered by an aircooled 5-8hp Briggs vertical shaft motor,running and inboard setup. The exhaust was aircooled, and was noisy, but nothing under the water but prop and rudder. They trolled, using 4 to 6 cane poles, about 10 feet behind the boat, and they caught enough trout on the flats to make a living. You couldn`t do that with any outboard. Fish quotas put an end to those boys.
boatdryver posted 07-22-2006 10:48 AM ET (US)
I was Steelhead fishing on the Chetco River in Oregon in an oar powered drift boat with a guide with 40 years of experience. At the end of some drifts he would row back upstream using eddies, but still hard work. Other drift boats were using small outboards to go back upstream.
I made a comment about the outboards spooking the fish. His opinion was that the fish get really used to the outboard motor sounds and don't associate that type of noise with predator risk.
He took special care to use gentle oar strokes, even rowing upstream, because the he believed pressure waves from violent oar strokes would be perceived by the fish as the tail drive of a giant predator fish, and would be more spooked than from outboard motor exhaust or prop noise.
Interesting point of view...
JimL
BobL posted 07-23-2006 11:25 PM ET (US)
In Boston Harbor the Striped Bass go into feeding mode when they hear a diesel engine because that is what the lobster fisherman use. The lobster boats re-bait their traps and the fish get fed in the process. The stripers get the old trap bait, and any crabs or short lobsters that get thrown back. The fish are conditioned to expect food when they hear an idling diesel.
The same noise conditioning occurs when charter skippers chum the same spots on a regular basis. I’m sure this phenomenon is common in many other areas.
pglein posted 07-25-2006 03:47 PM ET (US)
The noise that carries underwater is from the propeller, not the exhaust. You can't even hear the exhaust. To test this, stick your head underwater when your engine is idling. You'll see what I mean. Fish aren't scared by noise, the sea bottom is full of noise. What does scare them is sudden movement and/or noise. So yeah, common sense says that you don't want to go blazing full speed into the fishing grounds and expect the fish to sit there and just hop into the boat. But I wouldn't worry too much about engine noise scaring all the fish away.

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Author	Topic: Quiet Outboard: Effect on Fish
BOB KEMMLER JR	posted 07-18-2006 12:16 AM ET (US) With all the hype over quiet outboards lately, I wondered where does the noise go? If it is so quiet above the water, does this mean the noise gets pumped below the water's surface? If so what effect does this have for fishing areas like shallow grass flats where noise is a big no-no? Sure you can pole or run a electric trolling motor, but just how close can you get with your main motor before it spooks the fish?
jimh	posted 07-18-2006 12:24 AM ET (US) Even an older outboard motor, considered to be a loud motor by today's standards, was directing most of the sound of its operation into the water. The modern outboard which seems quiet to the operator is probably just as loud and likely louder to the fish. I was standing next to a 150-HP E-TEC which was running on an ear-muff style water hose adapter and an open-air exhaust. The technician gave the motor a quick shot of throttle advance. Without the immersion of the exhaust in the water, the sound level from the motor was extremely loud, and I literally jumped backwards from the shock of it as the motor revved up to a couple of thousand RPM. Yet, this same motor, when in the water and running at that same speed, was the quietest of all 150-HP motors tested in a recent "shootout." It was still producing all that sound, but in this case almost all of the sound is being directed out the underwater exhaust.
BOB KEMMLER JR	posted 07-18-2006 12:52 AM ET (US) I don't know why it posted double Jim?Yea i realize that most of the noise gets directed under the water(except some of the offshore dump type mids)but if it's noiser above the water,I'd have to think it's a little quieter under the water.i know some fish are attracted to the drone of diesels,or so it's said,but a lot of fish head for the hills when something noisy(to them)heads thier way.
Chuck Tribolet	posted 07-18-2006 01:04 AM ET (US) Having been on the bottom and heard a lot of boats go over -- they are ALL noisy. I think it's more prop noise than exhaust. Chuck
Perry	posted 07-18-2006 02:38 AM ET (US) When my neighbor, who lives 5 houses away, runs his classic 140 HP 2 stroke on the ear muffs at idle, I can here it in my living room. With my 135 HP 4 stroke running at idle on the ear muffs, I can't hear it 20 feet away.
Teak Oil	posted 07-18-2006 05:33 PM ET (US) When you are swimming and there are boats a couple hundred yards away on plane, go underwater and you will hear how loud the prop is in the water. It goes a LONG ways. This sound is much more significant than the exhaust
Binkie	posted 07-19-2006 07:10 PM ET (US) Sound must be the reason commercial fishermen seldom run Mercs, don`tcha think?
ratherwhalering	posted 07-20-2006 01:34 AM ET (US) I knew it! I am a good fisherman...it's just that darn quiet E-TEC scaring all the fish away. Now I can stop blaming he electrical field created by the engine every time I get skunked!
HAPPYJIM	posted 07-20-2006 07:02 AM ET (US) Noise can't be that much of a bother for them if trolling catches so many fish. Fish like barley and hops.....what better way to lure them in than a cooler full of cold ones!
Alex K	posted 07-20-2006 07:42 AM ET (US) Many dutch fishermen troll jerkbaits for northern pike and Zander (europ. walleye) in the many kilometers of very narrow and shallow canals they have. They catch fish in the bubble trail of their outboards. The canals are sometimes not deeper than 3-5 feet. So I don't think an outboard will spook fish if they're used to it. Alex
BOB KEMMLER JR	posted 07-20-2006 11:55 AM ET (US) Alex-Try motoring onto a flat and then try to count the redfish that are blazing away from you lol
CUOffshore	posted 07-20-2006 04:27 PM ET (US) Don't assume that noise is a bad thing. Your boat is the best "teaser" around. Noise can be a very powerful fish attractant. Some hull/engine combinations "raise fish" better than others, especially when trolling offshore. -Dave
Binkie	posted 07-20-2006 05:40 PM ET (US) back in the `70s in SW Florida, the commercial seatrout fishermen, would use a 14 ft. wooden skiff (rowboat) powered by an aircooled 5-8hp Briggs vertical shaft motor,running and inboard setup. The exhaust was aircooled, and was noisy, but nothing under the water but prop and rudder. They trolled, using 4 to 6 cane poles, about 10 feet behind the boat, and they caught enough trout on the flats to make a living. You couldn`t do that with any outboard. Fish quotas put an end to those boys.
boatdryver	posted 07-22-2006 10:48 AM ET (US) I was Steelhead fishing on the Chetco River in Oregon in an oar powered drift boat with a guide with 40 years of experience. At the end of some drifts he would row back upstream using eddies, but still hard work. Other drift boats were using small outboards to go back upstream. I made a comment about the outboards spooking the fish. His opinion was that the fish get really used to the outboard motor sounds and don't associate that type of noise with predator risk. He took special care to use gentle oar strokes, even rowing upstream, because the he believed pressure waves from violent oar strokes would be perceived by the fish as the tail drive of a giant predator fish, and would be more spooked than from outboard motor exhaust or prop noise. Interesting point of view... JimL
BobL	posted 07-23-2006 11:25 PM ET (US) In Boston Harbor the Striped Bass go into feeding mode when they hear a diesel engine because that is what the lobster fisherman use. The lobster boats re-bait their traps and the fish get fed in the process. The stripers get the old trap bait, and any crabs or short lobsters that get thrown back. The fish are conditioned to expect food when they hear an idling diesel. The same noise conditioning occurs when charter skippers chum the same spots on a regular basis. I’m sure this phenomenon is common in many other areas.
pglein	posted 07-25-2006 03:47 PM ET (US) The noise that carries underwater is from the propeller, not the exhaust. You can't even hear the exhaust. To test this, stick your head underwater when your engine is idling. You'll see what I mean. Fish aren't scared by noise, the sea bottom is full of noise. What does scare them is sudden movement and/or noise. So yeah, common sense says that you don't want to go blazing full speed into the fishing grounds and expect the fish to sit there and just hop into the boat. But I wouldn't worry too much about engine noise scaring all the fish away.