Raymarine L470 instruction manual Glossary of Terms

Glossary of Terms

Aft: Near or toward the rear part of the boat (nautical term).

Background noise: False or meaningless echo returns produced by bubbles, water turbulence, or debris

Bow: The front of the boat (nautical term).

Cavitation: Air bubbles in the water which affect the readings of a transducer. These are normally caused by mounting the transducer at an incorrect angle or location.

Chart Speed: The rate at which echoes scroll across the display.

Cursor: On a setup display, the place where the unit is ready to make a change or enter new information. This point is highlighted. You can move up or down the list or display using the < and V controls.

Deadrise angle: The slope or angle of the underside of the hull, mea- sured in the side-to-side direction.

Default value: A value or setting which is pre-loaded into the unit at the factory.

Fairing block: A block used when mounting a thru-hull transducer. The fairing block shims the transducer to align it on a perfect horizontal plane versus the rise of the hull.

Fathom: A unit of depth equal to 6 feet.

Frequency: The rate at which a sound source vibrates, or the rate at which a sound wave changes.

Fore: Near or toward the front part of the boat (nautical term).

Keel: The center of the hull, running from the bow to the stern.

kHz: “Kilo-Hertz” – a measure of frequency (For example, 200 kHz = 200,000 oscillations per second.)

Kick-up bracket: A bracket which is installed on the transom of a boat and holds the transducer in place. When the transducer strikes an obstruction, it is designed to release or “kick up” out of the water to prevent any damage.

Knot: One nautical mile per hour (1.15 statute miles per hour).

94 Glossary