Published Mar 3. 2009 - 15 years ago
Updated or edited Oct 27. 2021

Humminbird Smartcast 35

Despite its diminutive size, this innovative wrist-watch display and remote sonar sensor gives float tubers and kayakers a truly portable way to find fishy water faster. And at a MSRP of $80 USD, the price point is wallet friendly too. Read GFF's review of this handy (pun intended) device which may

Find more information on the manufacturers web page (This product is discontinued)


It puts out a modest 125-watt signal in a 20-degree cone, which translates into seeing a circle with a diameter about 1/3 of the depth of water you are in. For float tubes, that's all you'll want to would care less about what is 100' to the left of you. You can't get there fast enough to make a difference. I have a stream thermometer and checked the accuracy of the RF35 temp was on the penny. This boosted my confidence in the little unit. I dropped the anchor on my yak in 35 feet of water according to the RF35. Sure enough, I had about 12-14 feet of rope left (plus knots, etc) to make up my 50-foot section of rope. I hovered over a pod of bait fish and dropped some jiggy thing down in the midst of them...before you know it, they were off my little screen...they moved on because I was pestering them!

I suppose one day I'll have a more robust fish finder on my kayak, but for now, I am completely satisfied with the performance...its all I could really need, but of course I would always want more features. Want and need are two different things. If you are looking for structure, depth, fish markings and temp, this is the ticket at it's simplest form.


It doesn't do well when moving at modest speeds; it doesn't refresh fast enough. It's perfect on a kick boat, but a swiftly moving kayak, that's another story. However, when I settle down into troll speeds (2mph or less) it does fine. The small screen may bother some as well. I don't find it to be a nuisance because all I am looking for is the depth, temperature, structure and if there are fish in the area, which is what the watch face gives you. I don't need to tell how big the fish are or how many really. Just tell me what I am floating over...that's what I care about.


The little watch unit also has several controls & features that make it fisherman-friendly as well. You can turn off or on several features including beeping when fish are marked, auto depth scaling. When you aren't in the water, the watch unit stops detecting a signal from the depth sounder and functions as a standard digital watch. The watch face also has a polarization filter that lets you see the display even when wearing polarized lens. This is a big plus.


Since the transducer is a remote unit, ensure it is tethered off very securely...loosing it will render your device nothing more than a fancy watch. The transducer has a 500 hour battery life according to the manufacturer. That's several seasons on the water, assuming an average of 5 hours on the water per trip. Humminbird says you have to fork over another $25 for a new sealed and powered transducer. When mine dies, I want to dissect it to see if I can replace the batteries and reseal it watertight. I am no worse for wear if I try. By the way, the bottom of the depth sounder has two water sensors. When they detect water, the depth sounder turns on and starts sending a signal which the watch unit automatically picks up. This is a handy feature to save the battery life of the device. I take extra precaution to keep the device clean and dry at all times when not in use to prevent draining the battery.


It's not difficult to prepare the remote transducer for deployment. It's really lightweight and has a tendency to bob around quite a bit when in waves. Sometimes, it bobs to-and-fro too much that it appears to distort the depth readings. To keep the transducer "cone" facing downward all the time, simply attach a small weight to the bottom. The instructions even tell you to do this. I recommend using an old flyline or heavy mono to secure the device to your float tube or kayak. The last thing you'll want to worry about is if the device is still along side you as you kick around fishing.


I find this innovative device an added luxury when I tube or yak. I can't stand clutter on a float tube or kayak, nor do I want to paddle around extra weight of the larger portable units and batteries. Despite the diminutive size, you get features found on larger units such as bottom contouring, fish ID, temp and depth to 120 feet max. That's all one needs to fish most any lake, and for $80 USD retail...its a great price point. A wider cone would come in handy at times, but isn't really necessary. All-in-all, The Smartcast 35 is one handy device that has already turned my lake fishing into less exploration and more focused fishing. Now when people ask me how the fishing is..I can say the fishing was fantastic, and the catching was even better.

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CARLOS's picture

Great article, Steve...

Great article, Steve, Thanks!
I use the Smartcast for float tubbing. It is great for knowing the depth and the structure below the surface, I don't trust it for finding fish on lakes or rivers.
I attach the watch to the bar of the stripping apron of the tube, so it doesn't bother me while casting, and the transducer I fix it to a telescopic spinning rod which I fasten on a side of the float tube for better results.
Good fishing!


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