Humminbird 859 CI HD DI Fish Finder Review

Humminbird 859 CI HD DI Fish Finder Review

I read fish finder reviews until I was blue in the face before finally plunking down my hard-earned dollars. In the end, I ended up with the Humminbird 859 CI HD DI, and I couldn't be happier with it.

Quick Take: The Humminbird 859 DI is perfect for those who want a large screen fish finder that is dead simple to use. It has GPS and dual SD card slots, and works every time.

It isn't a great choice if you plan on creating a sophisticated network with multiple screens, but for those who want a fish finder that just works, this is the one.

Fish Finding Capabilities

If you're going to buy a fish finder, you want it to find fish, right? That's about like saying you want a smartphone to make phone calls.

Fish finders do a lot more than just find fish, but let's start with the basic fish finding capabilities. The transducer is one of the most important parts of the package.

I purchased my 859 CI HD DI from Cabela's for $699 in August of 2014, and it came with the transducer in the box. Be careful when buying from online retailers to check that they include the transducer. Some don't.

The transducer "precision" beam is 20 degrees and there's also a 60-degree wide view. I've found the fish finder to be quite accurate.  

Sometimes we'll troll over a school and then watch until the boat is 100' (or however much line we have out) past the school when right at that moment we get a strike.

One of my favorite things about this fish finder (though other fish finders of this quality do this as well) is that it gives color information about the fish you find.  

Kokanee salmon in Idaho lakes have larger swim bladders than trout, so when I go over a school I can often tell if it's a kokanee or a trout because the kokanee show up with a yellow dot in the center of the fish, which is that air pocket. Pretty cool, huh?

One limitation of this, and really all fish finders, is that it doesn't do a very good job at finding fish close to the surface. You can sometimes drive around all morning and rarely see a fish because all the fish are hanging out in the top five feet of water. However, this is easy to know because you'll see the fish rising.

Depth Finding

The Humminbird 859 has capacities of 859 watts of PTP and 500 watts of RMS output, which is good enough to get you down to about 600 feet. At least that's the advertised depth.  

I have not yet personally tested it to see how deep it can go because I use it in my local freshwater lakes, and they don't go deeper than 175 feet.

I find that the fish finder gives a full and accurate scan of the bottom when going up to about 14 miles per hour. After that, it still gives an accurate depth but not a perfect picture (and no fish finding at anything faster than 14 miles per hour).  

Your mileage may vary depending on how you mount the transducer. If you have a nice spot on the hull for the transducer, you may be able to go a little quicker.

On my pontoon boat, the transducer is mounted on the back bracket of the pontoon, so it's a reasonably good spot, but there's some turbulence.


If you're kind of a geek, you'll probably be put off at first when you begin looking at fish finders and see the low resolution screens they use despite the price tag.

This unit has a screen resolution of 800 x 480. It's hardly comparable to an iPhone 6 Plus screen at 1920 x 1080, but it actually looks better than you might expect. Humminbird does an excellent job cutting the glare on the screen.   

You'd be hard-pressed to see a cell phone screen on a bright day, but somehow the fish finder screen is always easy to see even from the back of my 22' pontoon boat.

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Installing the fish finder was more work than I had anticipated, but this is mostly due to the nature of how pontoon boats are laid out, and not necessarily because this particular unit was difficult to install.

I found that the box had just about everything I needed to install the fish finder, but it was missing a few things that I consider to be important.  

I wrote a full and in-depth post on how to install this fish finder on a pontoon boat here. If you get this unit and are ready to install it, this list will probably be helpful.  

This is a list of the materials I had to purchase to do the install on my 'toon that were not included in the box.

  • Six 1/4″ (.6mm) stainless steel bolts that are 1.25″ (3cm) long
  • Six stainless steel nuts
  • 20′ (5.7 meters) of electrical shroud (plastic conduit) - That’s the long coiled plastic tubing that goes around wires to protect them. For me, I used 3/4″, but I should have only gotten the 1/4″ because it would have been easier to fish the wires through the boat. The conduit only needs to be big enough to wrap around the transducer wire.
  • 6 stainless steel washers
  • 2 power connectors
  • A small tube of silicone (optional for a pontoon boat, but absolutely mandatory for installing on a traditional v-hull boat).

Ease of Use

A fish finder is a pretty advanced piece of electronical gear. It's incredible what the newer units can do. Although I'm quite the computer nerd, I was nervous about messing up the settings and not being able to get it back to working normally.

This was a problem that I had on my Lowrance fish finder previously. As it turns out, the Humminbird is incredibly simple to use.  

The menus are easy to navigate and each setting is explained well enough in the menu that you don't really even need the manual. Once you have this plugged in and powered up, you can just start driving around the lake.  

There's no need for tweaking at all. As I mentioned in my article about selecting a fish finder for your pontoon boat, the difference between Lowrance and Humminbird is much like the difference between Android and iPhone.  

Androids and Lowrances come with more features, more abilities for customization and are more tweakable. Humminbirds and iPhones often don't have the specs to match up and aren't very customizable, but they work consistently.


I was just about set to buy a Lowrance fish finder until I read reviews online. Seriously, go spend some time on Amazon reading reviews of the Lowrances.  

I couldn't count how many people spent $900 (or more) on a fish finder and wound up with a finicky device that they could never get to work right or was not durable.

One reason that Humminbird fish finders are less finicky is because they're made with proper hardware, which creates a more stable device.  

The processor in the fish finder is something that reviews never really mention, but it's very significant. Even with a maps SD card loaded in the device (which requires more processing power), I really don't see any delay in using the device. It starts up in about 20 seconds and chugs on from there.

Once or twice I've seen the fish finder "skip" where the water is at least 150 feet deep, and for a second it will glitch and say it is 5' deep or 2' deep, but this has been rare.

I also really liked that the unit came with a nice looking hard cover to put over the fish finder when in storage or not in use.


One cool thing that this fish finder can do is accept two SD cards. That's a nice benefit because you can purchase a Lakemaster (from Humminbird) or Navionics map card and slip it in the device.

If you do that, though, you usually don't have another SD card slot for adding an SD card to remember more waypoints, routes, etc. Having two memory card slots is a big bonus in my book. Most brands don't offer that because it takes up more processing power.

Since this fish finder has GPS, you have a huge benefit of being able to use maps. This is a good investment. Fish finders can tell you how deep you are at any given moment, but they can't show you shallow areas ahead of you unless it has maps built-in.  

I chose the Lakemaster maps ($120) for my region because I didn't want any bugginess. I figured that if it's made by Humminbird, it probably will work reliably.

I haven't tested Navionics, but I do like the Lakemaster maps. I figure it's worth the investment if it can keep me from running too shallow even once.

The Feature I WISH I Saw

Sometimes I think the fish finder market is ripe for innovation, but we really aren't seeing much of it from the fish finder companies. The screens are extremely low resolution, the processors are under-powered and there aren't third-party apps for fish finders like there really should be.

How cool would it be to have a fish finder app that could remember every single fish it finds and create a hot spot map for you?  

Or one that you can click a "hook up" button every time to get a bite or land a fish to remember that spot quickly and easily without creating a waypoint?  

How about one with Wi-Fi that could then send this information back to a central database so you can choose to share fishing info with others?

Even the ski boats would be adding to this database if they use a fish finder for depth finding. Then, when you get on the lake, your fish finder can show you where the fish have been on the lake over the last few weeks and historically.

The technology is all there. I'd love to see the implementation.    

Now it's time to put that fish finder to use and get out there and catch some fish. Put those rods, reels, cutting boards and other gear to use!