HD Undersea (StructureScan HD)
“Here we go,” I thought, as Stuart Wood scrolled through photos on his iPad like a proud parent. But then Wood — a manager with Navico Americas — stopped on one that blew me away: an incredibly detailed image of a sunken oil rig, taken from a fish finder equipped with Simrad’s StructureScan HD.
Paired with one of three Simrad multifunction displays, the black-box StructureScan HD unit returns incredibly crisp images, left and right to 300 feet with side-scan sonar as well as to 300-foot depths with down-scan. In split screen, you can see them simultaneously.
To test it, we positioned ourselves over a shipwreck and set the display to view the down scan, split with a traditional sonar return. In 120 to 125 feet of water, we saw the precise outline of a vessel listing on the seafloor. We could clearly make out its bow, stern and tower. In the traditional view, it looked like a large lump on the bottom.
“High frequency accounts for the detail of image,” Wood said.
Thanks in part to a larger, more refined transducer (see our Web Exclusive at boatingmag.com/transducers), StructureScan HD gets better resolution than previous models at 455 kHz (twice the normal “high” frequency). The higher the frequency, the sharper the bounce-back (but the less the range too). Side imaging also uses a narrow 180-degree beam compared with the more conelike beam of traditional sonar.
What’s the benefit to boaters? For divers, you can get a precise view of wrecks and reefs. For cruisers, you can get accurate pictures of mooring fields, and of potential hazards. For anglers, it should be fairly obvious.