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With an upcoming tubing trip on the Delaware river I started to research floating radios and came across this site. After seeing his floating cooler radio I knew I had to build one. Lucky for me I have a bunch of left over fiberglass supplies in the basement so minus the audio equipment it should be a relatively cheap project. Only problem is I only have about 2 weeks to build it. Jumping right in I ordered the audio equipment:

Amp
Dual - 300W Class AB Bridgeable 2-Channel MOSFET Amplifier w/Selectable Crossover. I pretty much choose this amp because it was cheap and I would care if it ended up at the bottom or the river. The customer reviews were also pretty good.

Speakers
2 pairs of Boss Marine - 6-1/2" 2-Way Coaxial Marine Speakers. Again they were cheap and rated well.

Miscellaneous
The waterproof on/off switch http://www.bikeraccents.com/.

The waterproof case for my iPod was from http://www.leisurepro.com/.

Lets get building. The base is made out of PVC pipe because it is cheap, light, and holds air. I figured this would create a 2 chambered design so even if the fiberglass part took on water it still may float. Once the pipe was glued together I screwed a couple of pieces of 1/4 inch plywood to the pipe to create the bottom of the raft. In trying to make this project as cheap as possible I just used a piece of scrap plywood I had in the basement. A larger single piece would have been better, but this will work.

Time to break out the fiberglass mat. I actually hate working with chopped mat, but it does build up quick and I have a huge roll of it. One layer on the top and one layer on the bottom.

For the sides I made a frame using some 1X2 and foam insulation. After taping the foam panels in place it was time for more fiberglass.

For the corners I tape pieces of poster board to the foam panels and laid fiberglass over them.

I used an angle grinder and a cut off wheel to open up the top. Then I used a sanding disk to knock down any of the high spots. This also reveled a few holes in the hull.

I wasn't looking for a surface so smooth you could paint it, but chopped mat just looks looks like shit. A quick coat of bondo and some sanding made it look much better.

After smoothing it out I went and covered it with some fiberglass cloth. Cloth is much easier to work with and lays down flat.

It was time for the moment of truth, the float test. Besides the fact that it hardly fit in the pool I purchased and that it tore a hole in the top two air cambers, the pool still held water and the radio floated. I completely over estimated how big this thing needed to be to float. I stood in the radio and it barely sunk down in the water.

To power the amp and speakers I am using an old truck battery. I used some 1X2's, 2 pieces of all thread and a piece of scrap aluminum angle. The all thread screws into T-nuts that are mounted to the bottom of the 1X2's. A little lock tight keeps them from spinning when you tighten the wing nuts. You can see where I had to flatten the aluminum for the wing nut to clear. It may not be pretty but it works.

Next up was cutting the holes for the speakers and cutting a piece of 1/4 inch plywood for the lid. Here again I am using T-nuts mounted in the underside of the frame to give the all thread something to thread into.

Next up was covering the top section of the radio in red/black carbon. I only had enough laying around to cover the top section so I just painted the bottom black. I didn't have a piece large enough to cover the top section in one piece, so I seamed together 4 pieces. Down each corner are 2 pieces of black cloth tape covering the seams.

Next up was lid. The first thing I did was cover the top section in tin foil to keep the blue painters tape from sticking to the radio. Once the foil was down I applied the painters tape. You will notice I created a little ledge to catch any excess resin from running down the side of the radio. The masking tape line is so I can see where to put the fiberglass and have a relatively strait line to follow. Fiberglass cloth wets out almost clear so the tape line stays visible.

With the shell done it was time to wire everything up. The amp is mounted on a make shift amp rack to keep it off the floor and out of any water that may leak in. The amp is rated 50W RMS x 2 channels @ 4 ohms (continuous); 75W RMS x 2 channels @ 2 ohms (continuous), so I decided to wire the each pair of speakers in parallel. This effectively turns each pair of speakers into a single 2 ohm speaker which gets 75W from the amp. Over all each speaker will receive about 37.5W. The amps remote turn on line is connected to a water proof switch mounted outside the hull next to one of the speakers. Finally I mounted the water proof case on the outside of the hull. The ipod to RCA line connects the iPod to the amp. The volume control on the iPod and the gain on the amp control the volume. I wouldn't call the project done, but it is good enough for now. The radio hits the water tomorrow morning.

09/11/10 Update
I am happy to report that the radio survived its first tubing trip. It was on the water for about 6 hours and it did fine. When we reached the campsite is was dark so I didn't get a chance to open it up and see how much water it took on, but in the morning there was maybe 1/8" of water in the bottom. Tubing season is pretty much over, but that doesn't mean I can get ready for next year. I learned from this trip that the speakers need more power. With the current set up each speaker is only getting about 37 watts and if you where more than 10-15ft way it was hard to hear. The upgrades I have planed include, a bigger amp to power the 4 existing speakers, a 10" sub woofer, an amp for the sub, a battery power indicator, and some straps to carry it.

Final updates until next year. The new/second amp has been installed. It is a MR800 Boss Marine 2 Channel Amp 800 Watts that I picked up from www.crispdeals.com. The amp is rated 125 RMS x 2 channels @ 4 ohms (continuous); 225W RMS x 2 channels @ 2 ohms (continuous), again the speakers are wired in parallel. This effectively turns each pair of speakers into a single 2 ohm speaker which gets 225W from the amp. Over all each speaker will receive about 112.5W, which is a nice step up from the 37.5W they were getting. We will see how it does on the water, but inside the house it seems much louder than before.

With old amp is now powering a 10 inch Boss Marine sub. With the amp bridged the sub is getting 175W RMS @ 4 ohms (continuous).

Because I have no idea how much water the radio took on while floating I decided to install a SeaSense Bilge Pump, float switch, and check valve. I think it is going to take a fair amount of water to set off the switch, so if I ever see it running I will know that the radio does take on a lot of water.

I needed some where to store this beast so I welded up a cradle and attached a winch to the ceiling in the garage. The rope is a back up just incase the winch lets go or slowly unwinds over time.