One of my fishing buddies has a stick-style fish finder from Bottom Line. It gave me a serious case of sonar envy. It started actively looking for one on eBay and other outlets. Then I came across All Kayak Fishing and saw a boat-style unit mounted on a tube. These sonars tend to be more powerful so I started to look for one of those as well. I soon scored a new-in-box Humminbird Matrix 10. The Matrix line is Humminbird's top line and is very expandable with GPS, WeatherSense and other goodies. The Matrix 10 is the smallest one but since this is a tube mount, I didn't want anything much bigger. After what seemed like an eternity, the Matrix finally arrived. After inspecting the parts and reading the manual, I started scheming how to rig this baby.
The first concern was how to power the unit. This model is intended for a boat, and boats have 12-volt batteries, herego I needed to get a 12v source for the tube. A car-size battery would be much too large and possibly dangerous to carry around on a float tube. After some research, it seemed a sealed lead acid (SLA) battery was the way to go. I guessed the sonar would draw about 250mA, so something in the 3-5AH range would do nice. I ended up getting a 4.2Ah battery at Powerstride Battery that is 2.75"L x 3.5"W x 4"H and weighs 3.5 lbs. This should give me plenty of juice for a whole day fishing. I also picked up a trickle charger with auto shut-off. The auto shut-off is an important feature since the battery is sealed and if overcharged, might explode.
The power cable for the sonar ended with just bare wire, so some connectors were needed. I crimped connectors onto the power cable leads. I then made a set of short (~12") leader wires. The female connectors fit perfectly (and quite snuggly) onto the battery tab terminals. There is no danger of those working themselves loose. The charger came with ring connectors made to fit over the big "Frankenstein" terminals found on a car batteries. I cut those off and replaced them with the females of my connnectors. This wiring scheme worked great and I powered up the unit (the Matrix series run in simulator mode if not in water). The following picture shows the entire wiring harness.
I now needed a way to mount the Matrix to the float tube. Using the forementioned ALK site as a guide, I made a set of mounting plates out of a plastic bucket. This was one of the kiddie meal buckets you get at the zoo; we have many of them lying around. The plastic is a bit more flexible than I really want, but it should work fine. I marked and drilled the mounting holes for the head. The following picture shows the two plates, the larger is for the head unit and the smaller for the transponder.
I then screwed the head base onto my plastic plate with some small machine screws (the unit comes with wood screws only). I put the screw heads on the bottom to avoid any sharp points against the tube body. I then mounted the transponder in a similar fashion to a smaller plastic plate. The Matrix 10 comes with the standard transom mount transponder that is meant to be mounted on the back of a boat. Humminbird offers an exchange program and I could have replaced my transponder with a puck-style unit. However, I didn't want to wait for that and I figure this one should work fine. Besides, mine has a build-in temperature sensor. I also cut slots for some straps to hold the whole thing in place.
The head unit from the rear showing the cables entering the unit.
As mentioned previously, the Matrix can be integrated with a GPS receiver. Humminbird sells a WAAS GPS reciever but they also offer a cable kit to connect up a hand-held GPS. Since I already have a Garmin eTrex, I went with the latter option. The cheapest I found the kit was on Angler Supply who had it on sale for $20 plus shipping. The cable has a eTrex connector on one end and a Matrix plug on the other. There is also an option to power the GPS receiver with the 12v source. However, I will use the eTrex's internal batteries since I am unsure if the eTrex can handle 12 volts. Since I won't be viewing the handheld's screen, I am planning on stowing it away when afloat.
This is a picture of everything being test-fitted.
