Furuno FSV-84 manual Application to Bonito and Tuna Fishing, Searching, Tracking, Approaching

3. VERTICAL MODE

3.13Application to Bonito and Tuna Fishing

Tracking of bonito and tuna presents a special challenge to the sonar operator: He must try to keep them within the sonar beam, a formidable task considering their high speed and penchant for leaping and diving. The FSV-84, however, with its vertical beam, makes this task easier.

3.13.1Searching

Neither the naked eye nor binoculars can continually track fish schools which make lightning quick runs between the surface and midwater. A sonar, however, provides a continuous view of several hundred meters of sea area around the boat, both at the surface and below it.

3.13.2Tracking

If you are visually tracking a fish school which characteristically leaps and dives regularly, or a school with a flock of birds hovering over it, the school will scatter once the vessel approaches, thus you will lose sight of the school. This sonar provides continuous pictures of underwater conditions, so you can always know where a fish school is. For tracking the schools which leap and dive often the vertical mode is especially effective.

Tracking

3.13.3Approaching

The sonar lets you view fish school movement continuously, thus you can approach a school confident of a good catch.

While a flock of birds hovering over the sea surface is usually a good indication of the presence of a fish school, the sonar can better verify fish school size.

Approaching

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