Navionics Fishing Ranges – Navionics App
It’s been about six months since Navionics added “Fishing Ranges” to their boating app and I’ve used it enough since originally writing this article about it that I thought a follow was in order. If you missed the first one, I recommend reading it as well as it explains how to use “Fishing Ranges” to add color to your chart. In this article I’m going to be focusing on how to use these colors to figure out the underwater lay of the land when fishing bays and harbors.
This screenshot of the Navionics Boating App from my ipad shows a section of San Diego Bay. I have the fishing ranges set the same in all of these screenshots. The pink area indicates 6 to 15-feet of water, the light green is 15 to 30-feet and the purple indicates water that is 30 to 60-feet deep. Sonar Charts show plenty of detailed contour lines by themselves and easily show areas of hard or rocky bottom, as is shown by the arrow pointing at the main channel just outside Kona Kai Harbor.
By adding colored shading less obvious things pop out, like the channels leading into the basin and extending under the docks. This information would be almost impossible to discern if you were to look at the uncolored chart. So why is knowing where the channels are important? Because they act as funnels for tidal flows and are a delivery system of food for the fish living in the bay.
This is another shot from San Diego Bay that shows the area around the Coronado Bay Bridge. I chose this area because the features are very obvious. There are two obvious channels off the main bay and the close contour lines show a steep drop off along the edge of the shallow water. Once you understand what the topography looks like you can make guesses as to where fish might be relating to it during different tidal flow directions.
This shot, from San Pedro Harbor is another example of how topography can effect where biting fish might aggregate. I’ve fished this section of the harbor many times but never understood why the fish were where they were until I uses Fishing Ranges to get a better picture. The point with the arrow indicating heavy current forms the right side of a pinch point in the harbor, with the shallows on the left forming the other side. This pinch point increases tidal flow in and out of the marina and more water movement means more potential food swimming and that means the area is likely to hold more biting fish.
Inside the marina, the colors show something that you’d never be able to figure out without them. Deep water, in excess of 30-feet, continues in past the main channel and branches out before getting shallow. There is also another spot of deep water towards the back of the marina. Having fished the marina in the past, I’d always assumed the water was all the same depth but now that I know it isn’t I can approach the fishery differently by targeting different sections, based on depth, to find biting fish.
Before I get into the final slide, this picture shows what most of Long Beach harbor looks like. Miles and miles of rip rap. Some of it seems to bite regularly but most of it doesn’t. Why is that? Well, Fishing Ranges really helps explain things.
This Navionics screenshot shows an area in Long Beach harbor that has lots of things going on. While most areas aren’t this obvious, the individual details are what really matter. The first notable feature is a ledge that comes out of deep water and extends at 15 to 30-feet far enough to create a flat of sorts. Along that flat are several shallower points and multiple wrecks. When viewed from the boat, this stretch of rip rap lined harbor doesn’t look like anything special, but when viewed with Fishing Ranges you can see why it would be more likely to hold biting fish than most areas.
The key to success when using Navionics Fishing Ranges is to adjust the depths to match those of the area you’re viewing. I didn’t randomly decide on the depths for this example, instead I played around with them until I found those that brought out the best detail for the area. If I were looking at Newport Harbor or Alamitos Bay with these settings I’d likely only get pink with a tiny bit of green because the water is shallow. Whatever depth you use you’ll want to adjust it so that you can use three or more colors to show the depth changes.