depth finder

Device that uses a sonic pulse to measure the depth of water below the boat.

alarm threshold setting

Knob for setting the maximum depth considered to be dangerous.

alarm threshold display button

Button that is pushed to display the alarm threshold value.

gain control

Knob for adjusting the amplification of the signal.

on-off switch

Button for activating the sounder and for selecting the scale.

sound alarm

Audible signal activated when the alarm threshold is reached.

housing

dial-type display

Display surface where an illuminated dot appears at the point on the scale that corresponds to the depth.

depth scale

Line graduated in feet or meters for reading the distance to the bottom.

echo sounder probe

Part of the sounder that is submerged to send the ultrasound to the bottom; it receives the echo and converts it into sound.

transmission cable

Electric wire that relays the electric signals between the housing and the echo sounder probe.

plug

Metal prong that plugs into the housing.

transducer

Part of the echo sounder probe that emits the ultrasound and receives its echoes.