What I want to do

I want to keep electronics dry while wired to underwater sensors. I did a short test of a simple system of caulk filled tubes stuck through rubber stoppers in the tops of pop bottles. I did a test submerging it half a meter (18") down in a trashcan full of water.

previously:

My attempt and results

New additions to the design:

• I used clear plastic tubing instead of brass tubing (3/8" OD (outside diameter) PET tubing)
• I ran wires down the length of the tube before filling with silicone caulk to simulate running sensors
• I filled the bottles with rice both to act as a desiccant (pulling moisture out of the air) and because it makes the bottle less compressible and I think will help maintain shape at depth. Also, rice sticks to moisture and I can use that to tell whether the bottles leaked.

I could fit four wires off a 0.1" ribbon cable through the tube.

Throwing it in the River

I threw it in and dragged it out three times just to be extra rough, then I tossed them about four feet (120cm) down.

I threw it in the water on the 16th of february and just picked it up at almost low-tide on the 25th (at 5:40pm). It was submerged under about 5' (150cm) of water at least some of last week.

NOAA Willamette River water levels:

here they are tied up at low tide when I retrieved them. ;

Questions and next steps

Go deeper-- attach real electronics and sensors.

Why I'm interested

$1 waterproofing