17.3How to recognize different types of fish

The swim bladders inside fish vary in their size and shape, depending on the type of fish. The air inside the swim bladder reflects the sonar pulse so the size of the swim bladder can affect the strength of the echo. With experience, it's possible to recognize the type of fish from the strength of the echoes that they're producing.

If you want to practice recognizing different types of fish, the A-Scope screen is useful.

When you're fishing amongst a school of fish and catching them, note the type of fish and the strength of the echo that they're returning on the A-scope screen. Then, when you see that particular echo again it's likely to be the same type of fish.

17.4How to recognize and avoid shadows

Shadows can hide fish from view. Shadows are likely to be created around areas such as hollows in the bottom or next to individual rocks and rocky ledges. The weak echoes returned from any fish in these areas are often obscured by the stronger echoes that are returned from the whole area.

A rocky ledge may produce a double bottom trace because the echoes are being returned from two different depths.

If you're fishing in areas with hollows, rocks and ledges, the 200 KHz frequency is the best choice because the high frequency, narrow sonar cone tends to reduce the effect of shadows. Shadows are more likely to occur with the 50 KHz frequency.

17.5How to recognize the type of bottom

Soft bottoms such as mud, weeds, or sand tend to scatter the sonar pulses resulting in a weak echo. These tend to appear as a narrow band on your Sounder screen.

Hard bottoms such as coral or rock usually reflect the sonar pulses strongly. These tend to appear as a wide band on your Sounder screen.

A rocky ledge reflects echoes from two different depths and is likely to produce a double trace on your Sounder screen.

If you're at anchor, all the echoes are returned from the same area of bottom. This produces a flat, uniform trace on your Sounder screen.

17.6How the water depth and scroll speed affect the history

The Sounder screen doesn't show a fixed distance traveled by your vessel; instead, it shows what's passed below the keel over a period of time. This is called the history.

The history is affected by two variables:

•the depth of water. In shallow water, the sonar signals have only a short distance to travel, so the Sounder screen shows a history that covers only a brief period of time and moves quickly. In deep water, the sonar signals have a

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NorthStar Navigation 8000I operation manual How to recognize different types of fish, How to recognize and avoid shadows
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8000I specifications

The NorthStar Navigation 8000i is a sophisticated marine navigation solution designed to enhance the safety and efficiency of marine operations. Utilizing the latest technology and innovative features, the 8000i provides users with a comprehensive navigation tool that is both user-friendly and highly reliable.

At the heart of the NorthStar 8000i is its advanced GPS integration, which delivers precise positioning and navigation capabilities. The system supports multiple satellite systems, allowing for exceptional accuracy and reliability in determining a vessel's location, even in challenging conditions. The 8000i uses Differential GPS (DGPS) to further improve positional precision, making it suitable for commercial vessels and recreational boaters alike.

One of the standout features of the NorthStar 8000i is its large, high-resolution color display, which presents information in a clear and accessible manner. The screen offers customizable layouts, allowing users to prioritize the data they find most critical. The interface is designed with simplicity in mind, enabling users to access navigation tools, charts, and other features quickly and easily.

The NorthStar 8000i is equipped with advanced cartography options, including support for a variety of chart formats. Users can choose between vector and raster charts, ensuring that they can find the best option for their specific needs. The system also supports both local and regional data, providing an extensive coverage area for vessels operating in different waters.

In terms of connectivity, the 8000i features integrated networking capabilities, allowing it to interface seamlessly with other marine electronics such as radar systems, autopilots, and AIS transceivers. This interoperability enhances situational awareness and provides a comprehensive picture of the marine environment around the vessel.

The rugged design of the NorthStar 8000i ensures that it can withstand the challenging conditions often encountered at sea. Built to be weatherproof and durable, this navigation system is ready for any marine adventure.

To summarize, the NorthStar Navigation 8000i combines cutting-edge GPS technology with user-friendly designs and exceptional features, making it a top choice for navigators seeking reliable marine navigation solutions. With its accuracy, customizable interfaces, and robust construction, the 8000i is engineered to meet the diverse needs of modern sailors, whether for leisure or professional undertakings.
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