USING SIDESCANNING SONAR TO FIND YOUR PROP
A conventional fish finder is useless for locating a static item like a propeller on the bottom. The single sonar beam will simply show the bottom as being fractionally shallower as you go over an object.
What you need is technology providing a 3D image – a forward-scanning or side-scanning solution – which delivers detailed, high-resolution images capable of showing an outboard prop sticking up out of the sand.
Side-scanning technology works because the ping goes out to either side of the boat. As the echo from an object is detected so too is the ‘shadow’ behind it, which when displayed on the screen will readily show the object’s shape. The distinctive blades of a prop will show up, unless it fell into an area that cannot be seen – such as a crack between boulders or other bottom debris.
ABOVE Side-scan (above) or forwardscanning sonar can show objects on the bottom conventional sonar cannot. LEFT Side-scan shows the object and the ‘shadow’ behind it.