Introduction: River Radio- Floating Stereo That ROCKS!

By Flynn Audio
About: I work as a pharmaceutical chemist to fund my hobbies which are: motorcycling, building stereos into things, installing car stereos, and going to live music events.

A few years back a friend wanted me to build a floating stereo for his yearly lazy river trip. We didn't have the funds at the time but since I opened up a stereo installation shop I've gotten access to tons of cheap and second hand parts. This year I got invited to go on a lazy river down the Wisconsin river so I knew it was the right time to build a prototype.

The ice chest/cooler boom box has been done 1000 times so I knew I had to think of something different, and I didn't want to completely butcher a working cooler. My original sketches were to made a floating unit that looked like an ocean buoy but that had speakers built into it. My second sketch was to make a tall pyramid of the iconic yellow "Slippery When Wet" sign. However after some thought I decided that I should try to make this particular radio have as low a center of gravity as possible. Many other ideas including cup holders, waterproof storage etc were thrown out in lieu of cost effectiveness and time to build. Bottom line we've got a dedicated stereo with a simple design.

As per usual, I forgot to take as many pictures as I would have liked during the build process, please feel free to ask any questions.

Step 1: Wood Cuts

The enclosure is comprised of three main parts.

  • -3/4" Plywood
  • -5 gallon pail
  • -Implement(farm) inner tube

Again, I used SketchUp to help me create proper dimensions that would allow everything to fit well.

The whole top half uses 3/4" plywood, about a half sheet. It got painted with outdoor paint first, then fluorescent orange to ensure it was easy to spot should it decide to go floating away. As it turns out the orange also attracted a lot of people to come over and ask about it, win!

The design is just a square on top of a circle! The sides have 45 degree cut ends to keep the lines nice and also to minimize rough surfaces. I glued and nailed the 4 sides together first and then mounted it to the circular surface. I used 2x4s that are cut in half and then screwed in from the bottom as corner braces. The sides are then screwed into the posts, and the top is too. Considering my lack of wood tools for setting the glue, screws and nails it came out very strong.

I knew I wanted to use a 5 gallon pail as a base for a few reasons:

  • To place the battery at the bottom to lower the center of gravity
  • To act as a dagger board to minimize tipping/tilt (Like a sailboat!)
  • To use as a stand on shore and in storage because it is less prone to dents than wood
  • The cost, weight, and fitment inside an inner tube.

Finally the implement tube. I didn't need anything too big for this little radio. I believe the inner diameter is 16" and the outside is about 24". It fits my needs very well. It is tied to the round base using poly rope, eyelets and some new knots I learned.

Step 2: Paint!

Rolled on white exterior paint, a couple coats on all outside surfaces. Once that was dry used just 1 full rattle can of the orange fluorescent paint. I thought about a clear coat on top of the orange but it seemed to hold up well against the water on the test float so I decided against the added expense.

Step 3: Electronics

As I mentioned I have access to inexpensive parts as well as second hand gear that people give to me. In this stereo we have:

  • 1 Clarion Marine CD player (used)
  • 4 Kenwood 6x9 speakers (new)
  • 1 SPST switch (used)
  • 1 Kinetik car stereo battery (new)
  • Various wiring, fuse, quick disconnect for the battery

The Clarion head unit is older, only has radio and CD(non MP3), and wasn't working when I got it from a ski boat I worked on a few weeks back. I took the faceplate apart and found out the power button was faulty. Ordered some new ones online, replaced it, and it fired right up!

Kenwood speakers are not marine grade but do have poly cones, rubber surrounds, and full mesh grills so I wasn't worried about them getting water damage so long as it never sank (it didn't).

The switch is used just like the key would be in a car, simply for on off. Memory wire from the radio stays on the battery and since I don't have to unhook the battery to charge it I can keep radio and EQ presets because I'm anal like that.

Originally I was going to use a lawn and garden battery but the guy at Batteries Plus was very helpful and explained that while those batteries have big cranking amps they probably wouldn't last all day long at the beach due to their low RC (Reserve Capacity). The battery I got instead was still only $60 shipped, is smaller, sealed, and has a big RC. I had the radio on at moderate to high volumes for 9 hours on the water and in a back yard and the battery tested at 12.1V when I got home, pretty impressive.

Step 4: Putting It All Together

For mounting the plastic pail to the wooden enclosure I cut the hole in the center of the board big enough for the top of the pail to fit through, but not big enough to fit over the shoulder. Then I screwed through the pail and into the wood from the inside and sealed the top and bottom with silicone to ensure my project wouldn't take on water. Radio got mounted below one speaker to allow plenty of room above it to vent heat to instead of venting right into the top board which would have likely caused it to overheat quickly in the sun.

As mentioned the inner tube was secured using poly rope, some basic knots, and 8 eyelet screws. I also added a 10' mooring line with a cheap carabiner at the end so that I could attach the radio to most anything and keep it from floating away.

Overall this project was a total success! The sound kept pumping out all day long, it was plenty loud, it didn't sink, and it got a lot of attention from other groups of lazy river goers.