Friday, February 27, 2009

Transducer Cone Angles

The transducer concentrates the sound into a beam. When a pulse of sound is transmitted from the transducer, it covers a wider area the deeper it travels. If you were to plot this on a piece of graph paper, you would find that it creates a cone shaped pattern, hence the term "cone angle." The sound is strongest along the center line or axis of the cone and gradually diminishes as you move away from the center.

In order to measure the transducer's cone angle, the power is first measured at the center or axis of the cone and then compared to the power as you move away from the center. When the power drops to half (or -3db[decibels] in electronic terms), the angle from that center axis is measured. The total angle from the -3db point on one side of the axis to the -3db point on the other side of the axis is called the cone angle.

This half power point (-3db) is a standard for the electronics industry and most manufacturers measure cone angle in this way, but a few use the -10db point where the power is 1/10 of the center axis power. This gives a greater angle, as you are measuring a point further away from the center axis. Nothing is different in transducer performance; only the system of measurement has changed. For example, a transducer that has an 8 degree cone angle at -3db would have a 16 degree cone angle at -10db.

Although the half power point is the standard for measuring cone angles, fish detection angles are much larger. Lowrance sonar units have very sensitive receivers and can detect return echoes from fish, structure or the bottom out to 60° or more. This means that the fish detection angle is 60° even though the cone angle is only 20°.

20 degree cone angle | 8 degree cone angle
Lowrance offers transducers with a variety of cone angles. Wide cone angles will show you more of the underwater world, at the expense of depth capability, since it spreads the transmitter's power out. Narrow cone angle transducers won't show you as much of what's around you, but will penetrate deeper than the wide cone. The narrow cone transducer concentrates the transmitter's power into a smaller area. A bottom signal on the sonar unit's display will be wider on a wide cone angle transducer than on a narrow one because you are seeing more of the bottom. The wide cone's area is much larger than the narrow cone.

High frequency (192 - 200 kHz) transducers come in either a narrow or wide cone angle. The wide cone angle should be used for most freshwater applications and the narrow cone angle should be used for all saltwater applications. Low frequency (50 kHz) sonar transducers are typically in the 30 to 45 degree range. Although a transducer is most sensitive inside its specified cone angle, you can also see echoes outside this cone; they just aren't as strong. The effective cone angle is the area within the specified cone where you can see echoes on the display. If a fish is suspended inside the transducer's cone, but the sensitivity is not turned up high enough to see it, then you have a narrow effective cone angle. You can vary the effective cone angle of the transducer by varying the receiver's sensitivity. With low sensitivity settings, the effective cone angle is narrow, showing only targets immediately beneath the transducer and a shallow bottom. Turning the sensitivity control up increases the effective cone angle, letting you see targets farther out to the sides.


http://www.fishfindergarage.com/

Wednesday, February 25, 2009

What is a transducer

The transducer is the sonar unit's "antenna." It converts electric energy from the transmitter to high frequency sound. The sound wave from the transducer travels through the water and bounces back from any object in the water. When the returning echo strikes the transducer, it converts the sound back into electrical energy which is sent to the sonar unit's receiver. The frequency of the transducer must match the sonar unit's frequency. In other words, you can't use a 50 kHz transducer or even a 200 kHz transducer on a sonar unit designed for 192 kHz! The transducer must be able to withstand high transmitter power impulses, converting as much of the impulse into sound energy as possible. At the same time, it must be sensitive enough to receive the smallest of echoes. All of this has to take place at the proper frequency and reject echoes at other frequencies. In other words, the transducer must be very efficient.


http://www.fishfindergarage.com/

Monday, February 23, 2009

Shellfish Paella

Al Dente's Shellfish Paella in a Clay Casserole

1/3 cup olive oil
2 pounds white onions
2 1/2 pounds tomatoes
2 pounds green peppers
16 manila clams
8 mussels
1 pound squid
8 jumbo shrimp
1/2 pound Spanish chistorra
1 pound chicken
1 1/2 cups short rice
Touch of saffron
2 liters chicken broth

Heat oil in a shallow clay casserole or large skillet. Add onions and sauté slowly over low heat, adding tomatoes, peppers, chistorra, chicken, squid, clams, shrimp, mussels and saffron.
Add rice and chicken broth. Cook for about 25 minutes.
Let stand 10 minutes before serving.

http://www.fishfindergarage.com/

Friday, February 20, 2009

Fishing with my dad

When I was 13 my father asked me if I wanted to go fishing with him and my brother. I said yes and it was a nice clear summer morning and we headed down the shore.We boarded a party boat and a little while after that we headed out to the captains fishing spot and dropped our lines.We did not fish a lot so we used their rods and the mates took care of everything but reel in the fish when we hooked one.My brother got sea sick and went inside to sit down and me and my father both hooked a fish.When we reeled them in I had a blue fish and my father had a small fluke that had to be thrown back because it was too small to keep.Throughout the day we caught 4 more fish and the last fish before we headed in was on my line.I reeled it in slow because I was only 13 and not very big and when it came up it was a huge doormat fluke that was easily the biggest fish of the day.


http://www.fishfindergarage.com/

Thursday, February 19, 2009

Fish finder frequency

Most sonar units today operate at 50 kHz - 200 kHz (kilohertz) and there are advantages to each frequency, but for almost all freshwater applications and most saltwater applications, 192 or 200 kHz is the best choice. It gives the best detail, works best in shallow water and at speed, and typically shows less "noise" and undesired echoes. Target definition is also better with these higher frequencies. This is the ability to display two fish as two separate echoes instead of one "blob" on the screen.

There are some applications where a 50 kHz frequency is best. Typically, a 50 kHz sonar (under the same conditions and power) can penetrate water to deeper depths than higher frequencies. This is due to water's natural ability to absorb sound waves. The rate of absorption is greater for higher frequency sound than it is for lower frequencies. Therefore, you'll generally find 50 kHz used in deeper saltwater applications. Also, 50 kHz transducers typically have wider coverage angles than 192 or 200 kHz transducers. This characteristic makes them useful in tracking multiple downriggers. Thus, even when these downriggers are in relatively shallow depths, 50 kHz is preferred by many fishermen. In summary, the differences between these frequencies are:

192 or 200 kHz

* Shallower depths
* Narrow cone angle
* Better definition and
target separation
* Less noise susceptibility


50 kHz
* Deeper depths
* Wide cone angle
* Less definition and
target separation
* More noise susceptibility



http://www.fishfindergarage.com/

Wednesday, February 18, 2009

Total System Performance

There are four facets to a good sonar unit:

•High power transmitter.
•Efficient transducer.
•Sensitive receiver.
•High resolution/contrast display.

We call this our "Total System Performance" specification. All of the parts of this system must be designed to work together, under any weather condition and extreme temperatures.

High transmitter power increases the probability that you will get a return echo in deep water or poor water conditions. It also lets you see fine detail, such as bait fish and structure.

The transducer must not only be able to withstand the high power from the transmitter, but it also has to convert the electrical power into sound energy with little loss in signal strength. At the other extreme, it has to be able to detect the smallest of echoes returning from deep water or tiny bait fish.

The receiver also has an extremely wide range of signals it has to deal with. It must dampen the extremely high transmit signal and amplify the small signals returning from the transducer. It also has to separate targets that are close together into distinct, separate impulses for the display.

The display must have high resolution (vertical pixels) and good contrast to be able to show all of the detail crisply and clearly. This allows fish arches and fine detail to be shown.


http://www.fishfindergarage.com/

Monday, February 16, 2009

Sonar tutorial for Lowrance and how it works

Sonar Tutorial

People have been fishing for thousands of years. Every person fishing has had the same problem - finding fish and getting them to bite. Although sonar can’t make the fish bite, it can solve the problem of finding fish. You can’t catch them if you’re not fishing where they are - and the Lowrance sonar will prove it

In the late 1950s, Carl Lowrance and his sons Arlen and Darrell began scuba diving to observe fish and their habits. This research, substantiated by local and federal government studies, found that about 90 percent of the fish congregated in 10 percent of the water on inland lakes. As environmental conditions changed, the fish would move to more favorable areas. Their dives confirmed that most species of fish are affected by underwater structure (such as trees, weeds, rocks, and drop-offs), temperature, current, sunlight and wind. These and other factors also influence the location of food (baitfish, algae and plankton). Together, these factors create conditions that cause frequent relocation of fish populations.

During this time, a few people were using large, cumbersome sonar units on fishing boats. Working at low frequencies, these units used vacuum tubes which required car batteries to keep them running. Although they would show a satisfactory bottom signal and large schools of fish, they couldn’t show individual fish. Carl and his sons began to conceptualize a compact, battery operated sonar that could detect individual fish. After years of research, development, struggle and simple hard work, a sonar was produced that changed the fishing world forever. Out of this simple beginning, a new industry was formed in 1957 with the sale of the first transistorized sportfishing sonar. In 1959, Lowrance introduced “The Little Green Box,” which became the most popular sonar instrument in the world. All transistorized, it was the first successful sportfishing sonar unit. More than a million were made until 1984, when it was discontinued due to high production costs. We’ve come a long way since 1957. From “little green boxes” to the latest in sonar and GPS technology, Lowrance continues to lead in the world of sportfishing sonar.


How it Works

The word "sonar" is an abbreviation for "SOund, NAvigation and Ranging." It was developed as a means of tracking enemy submarines during World War II. A sonar consists of a transmitter, transducer, receiver and display.

In the simplest terms, an electrical impulse from a transmitter is converted into a sound wave by the transducer and sent into the water. When this wave strikes an object, it rebounds. This echo strikes the transducer, which converts it back into an electric signal, which is amplified by the receiver and sent to the display. Since the speed of sound in water is constant (approximately 4800 feet per second), the time lapse between the transmitted signal and the received echo can be measured and the distance to the object determined. This process repeats itself many times per second.

The frequencies most often used by Lowrance in our sonar are 192 - 200 kHz (kilohertz); we also make some units that use 50 kHz. Although these frequencies are in the sound spectrum, they’re inaudible to both humans and fish. (You don’t have to worry about the sonar unit spooking the fish - they can’t hear it.)

As mentioned earlier, the sonar unit sends and receives signals, then “prints” the echo on the display. Since this happens many times per second, a continuous line is drawn across the display, showing the bottom signal. In addition, echoes returned from any object in the water between the surface and bottom are also displayed. By knowing the speed of sound through water (4800 feet per second) and the time it takes for the echo to be received, the unit can show the depth of the water and any fish in the water.


http://www.fishfindergarage.com/

Friday, February 13, 2009

What is a Chartplotter and why do I need one?

A chartplotter is an electronic navigation system that combines a GPS receiver with the capability to display electronic charts/maps, letting you continuously monitor the position and movement of your boat in relation to the surrounding physical environment, both above and below the water.

With its integral processor combining GPS data with electronic charts — the accuracy of which influences the efficiency of the system — a chartplotter pinpoints the location of your boat and can use the GPS data to calculate boat speed and direction, as well as determine the time and distance to the destination or next waypoint. It displays all this data in real time so that a navigator knows exactly where his boat is and where it’s heading, as well as continuously updating its position relative to its surrounding physical environment..

Boat owners often use chartplotters to preload routes that can then be edited at any time before or during the trip. Some chartplotters allow the navigator to store hundreds of routes at a time for future use. Each route consists of a number of waypoints to assist navigation and avoid hazards, such as shallow rocks or reefs, represented by longitude and latitude references and depicted on a screen to give a visual representation of the boat’s surroundings. Each waypoint is a numbered position and as the boat progresses past each one the system indicates the distance travelled and course remaining until the next waypoint. It will also show if the boat has strayed off course and provide information to correct the bearing in order to arrive at the next waypoint.

With the combination of GPS functionality and embedded charts, chartplotter have become an essential navigational tool which is relatively inexpensive to buy and easy to install and use on any type of craft. With a single SD card now capable of storing electronic charts for the entire western coast of the U.S., they are remarkably cost-effective.

Today’s chartplotter has come a long way from conventional paper charts and they often feature a range of additional functions including man overboard markers, zoom abilities and much more. Manufacturers, however, continue to recommend that boat owners continue to carry paper charts for important areas, in case of power failure.


http://www.fishfindergarage.com/

Thursday, February 12, 2009

Fish Finders- The first step is to figure out what fits into your budget. Once you know the amount you can spend,look at the features available for these fish finders to determine what features interest you so you can catch more fish.

Common Features of the Best Fish Finders


In general we recommend the purchase of simpler fish finders for beginners and then step up to advanced further down the line. There are a lot of features to learn about on the advanced fish finders so if you’re a beginner start simple and save yourself a few dollars.



For most people LCD finders will work great. CRT displays are great, but they require a lot of power and the cost of these fish finders really makes them more of a luxury than a need. LCD finders will find fish just like the CRT will without all of the unneeded features for your average weekend fisherman.

When it comes to fish finder displays, being able to read it in direct sunlight is half the battle. Any quality brand name LCD finder should work fine for most fishing needs.

Frequency of the fish finders is expressed in kHZ, you will have a variety to choose from. High frequency fish finders are for smaller bodies of water and show great bottom and fish detail. Low frequency finders are for larger bodies of water both from a depth and width perspective.

Good fish finders can make the difference between a great day of catching fish and a good day of fishing.


http://www.fishfindergarage.com/

Wednesday, February 11, 2009

Broiled Bass Recipe

Broiled bass

Ingredients
1/4 cup lemon juice
1/4 cup lime juice
1 tsp. minced garlic
1/4 tsp. ground ginger
1 tbsp. brown sugar
1/4 tsp. pepper
1/2 tsp. salt
1/2 tsp. Dill weed
1-1/2 pounds fillets

Preparation
Combine all ingredients except fish and mix well. Place fillets in a large ziplock bag and pour the marinating mixture over them. Push out air and seal the bag. Refrigerate for at least 3 hours, turning the bag over midway.

Cooking
Spray the broiler ban with nonstick cooking spray. Remove the fillets from marinade and place them on the pan. Broil for 8-10 minutes, until fish is firm and opaque, and easy to flake with fork.

http://www.fishfindergarage.com/

Tuesday, February 10, 2009

Early morning fishing trip

It was a very brisk early November morning and we were scheduled to leave the dock at 5am. I left my house at 4am,stopped at a deli and got a taylor ham,egg and cheese sandwich and a coffee and headed to the marina.Everyone arrived right behind me and grabbed the coolers and gear and boarded the boat.As we were headed out we ate and the mate set up the rods for those who did not have their own and in about an hour we are at a spot that the Furuno fish finder told the fish were.We are fishing for stripped bass and are using live eels on this day and it is absolutely freezing out on the water.In about 10 minutes I hooked one and started reeling it in and it is giving me a good fight.The mate grabs the net and pulls it in and let me tell you this fish was 45 inches and heavy,they did not have a scale to weigh it,and it was ultimately the biggest fish caught that day.Everyone pulled in their limit of 2 keepers and the captain had 2 tags so we had 2 extra fish and also had quite a few blue fish that I split with 1 other person because not too many people care for them.It was a great trip all around but very cold for early November but we could have stayed out all day if we could.

http://www.fishfindergarage.com/

Monday, February 9, 2009

What are you looking for

WHAT ARE YOU LOOKING FOR?

The depth determines the fishing technique, and what type of lure or bait. The finder lets you see who may be at home down there, but it will not guarantee a catch. That part is up to your skills. In most fishing you will use your unit to look for underwater structure, such as tree stumps, ledges and significant bottom changes. Cover consists of underwater object such as tree stumps, weed beds, logs etc. You may also be looking for drop-offs which are gullies and channels or break-lines, which is a sharp bottom drop off point. You may just be looking for fish activity. If you locate a tight ball of baitfish then they are probably being chased by a predator. A loose school indicates no activity.

A finder is not necessarily going to tell you what the fish is. Image interpretation involves understanding both the underwater features and fish behaviour to distinguish between bait fish and the target fish. Distinguishing between the bass and the shad or other species is the angling part.

http://www.fishfindergarage.com/

Sunday, February 8, 2009

Cajun Fried Bass

Cajun fried bass

Ingredients
1/2 cup Bisquick
1/4 cup milk
1 egg
1 cup corn meal
2 tsp. cajun seasoning
1/4 tsp. salt
1-1/2 pounds bass fillets
oil for frying

Preparation
Whisk together the Bisquick, milk and egg in a medium bowl. Mix the corn meal, cajun seasoning and salt in shallow dish. Dip the fillets into the wet batter first, then dredge in the corn meal mixture.

Cooking
Fry the fillets in hot oil until golden brown, turning once. Drain on paper towels and serve. Ranch dressing makes a great dipping sauce for this

http://fishfindergarage.com/

Friday, February 6, 2009

How sonar works

AN INTRODUCTION TO SONAR

The fish-finder started off as a submarine finder. The recent developments in computing power and microelectronics have resulted in major advances in SONAR development.

I spent a couple of years on new submarine SONAR systems, and this defense level capability has now entered the fishing world. The term SONAR is derived from the words SOund NAvigation Ranging.


HOW DOES SONAR WORK?

An fish-finder electrical signal is sent to the transducer. The electrical signal to energize the transducer crystal is generated by an amplifier. The energized crystal reverberates at a particular frequency, to convert the electrical signal into mechanical acoustic or sound energy. The acoustic energy or sound waves causes oscillation of the water molecules through which the sound travels. The sound is pulsed out in a defined beam. These do not travel out in a straight line but in a wave pattern. The acoustic pulse travels through the water at a rate of approximately 4800 ft (1500m) per second in saltwater and 4920 ft/sec in fresh water.

When the energy strikes an object within that beam such as fish, the sea bottom, or a structure then some of the energy is reflected, or echoed back to the transducer. The transducer collects this return, passes it back to the unit and this processes it into display data. As the processor is programmed with the rate of sound transmission in the water it calculates the time difference between the transmission and reception of the returned signal to give a range or depth figure. This result is then displayed as a number or as an image on a screen.

Freshwater and saltwater tends to absorb and scatter sound signals, and the higher frequencies are more susceptible than lower frequencies. Water is frequently being mixed due to environmental factors such as wind and wave actions. The water has air bubbles, suspended materials such as silt, minerals and salts that vary in quantity. There are also micro-organisms that include plankton and algae, all which scatter, absorb and reflect sonar signals.

http://www.fishfindergarage.com/

How fish finders work

All fishfinders operate using Sonar. Developed during World War II, this technology uses sound waves to "view" underwater objects. A sound wave is produced by the fishfinder and sent through the water. At the source, the wave is narrow; however as it penetrates deeper, the sound wave spreads forming a cone, or what is commonly called a beam (think flashlight). When the sound wave encounters something within this beam, it bounces back to the fishfinder. By measuring the very small amount of time between when the sound wave was send out and when it bounces back your fishfinder calculates the distance and draws it on the screen.

If the signal doesn't encounter anything along the way, it reaches the bottom. Soft bottoms like mud and weeds tend to absorb the signal. Hard bottoms such as rock reflect a stronger signal back. These subtle differences in sonar reflections appear on the display screen. That's how a fishfinder "reads" the bottom and everything in between.

Depth finders, or fish finders, are sonar units that bounce sound waves off the bottom of the lake to determine water depth and the presence of objects between the bottom and the surface. The first fish finder used a rotating diode, while units today use liquid crystal or CRT displays to show the bottom and fish that may be present.

http://www.fishfindergarage.com/