Depth Capability:
600 feet
Display Matrix & Size:
160 V x 160 H Pixels, 3" V x 4" H
Display Type:
FSTN Liquid Crystal Display
Unit Size (installed):
7.75" H x 7.875" W x 4.25" D
Power Requirement:
12 VDC
Operating Frequency:
200 kHz
Sonar Coverage:
24 degrees @ -10db
Transducer (Standard):
Single Beam XT-6-24 with 20 foot cable
Capable, Temp Included
Power Output:
2400 Watts (Peak to Peak), 300 Watts (RMS)
Made in U.S.A.




















After using a 100SX for a couple of years, I was ready for something with a little more kick.  A sonar with a little more power and a larger LCD.  As I was searching through Humminbird's website, I quickly noticed one of their latest models the 405SX.

Selecting a sonar device can be as personal as shopping for a kayak.  Some people like a wider area of beam coverage.  They may select a fish finder with multiple sonar beams.  This helps cover a larger area and certainly makes it easier to spot large schools of fish.  Some people like a narrower beam to focus on a specific area.  They prefer looking just at what is directly beneath them.  

I was in the market for a powerful single beam.  My priority was to have a powerful transmitting sonar with a single beam transducer.  With that I could better identify the ocean floor (bottom) directly beneath my kayak.  Whether it was sandy, rocky or stacked thick with kelp, I wanted a bigger, better picture with greater detail to view it.  I turned to Humminbird's 405SX to get that enhanced sonar performance.

The 405SX transmits a  more powerful beam than what I was previously use to.  I immediately noticed the difference in detail as I paddled out towards the kelp beds.  When I was directly over the kelp bed, the display was showing the individual columns of kelp.  The images reflecting the shape and structure of the kelp columns were easy to interpret.  With the larger display size to accompany the enhanced performance, I was in for a greater sonar experience.

I set the fish id and the fish alarm at various settings to see how it interpreted the sonar data.  It seemed to perform well.  Usually I set the fish alarm to only sound for larger fish.  Though it depends on what type of fish you're targeting. When I'm searching for larger schools of baitfish, I set the fish alarm to sound for all objects the 405SX interpret as fish.

There are some other features which were new to me.  The True Zoom feature got me off of the fence when I was trying to decide which fish finder to go with.  You can zoom right up on the ocean bottom.  I like  to get up close and personal with what's going on at the bottom.  As I stated earlier, what I really wanted out of a fish finder was a good reading of the ocean floor.  The True Zoom with Auto Zoom feature allows you to view a small area of the ocean floor without giving up your perspective of the entire water column beneath you.

Other features include speed control, sensitivity, depth alarm, bottom black, enhanced diagnostic, fish id and alarm (as previously mentioned) and more.

I like the freedom the quick connect tilt and swivel mount offer.  You can launch and land your kayak with the 405SX safely stowed below deck since the unit easily connects and disconnects from the mount.  

The 405SX is waterproof but it isn't bullet proof.  Take extra care of it and you may not have to send it into service for repair.  Salt water and electronics don't mix well together sometimes.  I recommend purchasing the extended 2 year factor warranty just in case.  From experience, Humminbird has a fantastic service department with a minimal turn-around time.  They'll get your sonar back in shape in no time.

I am very pleased with the performance of Humminbird's 405SX.  Though I still haven't seen the kind of resolution the pictures on the box and web site depict, overall I am still very satisfied with how the 405SX performs.  It's an excellent unit and value for the price.


Reviewed August 5, 2002
by Jason Morton