Designing a high sensitive surface wave pickup bouy.

To detect the very small waves, that propagate from the impact of a stone in water, I needed a very sensitive pickup.

Basicly the wave detection is done by an accelerometer (LIS302DL) connected to an Arduino board.

Single bouy design
I tried just putting the accelerometer inside a single bouy. This didn’t give me the sensitivity I needed.

• To house the Arduino board, the bouy needs to have a certain size = weight.
• The anchorline of the bouy act as a damper of the movement = reducing sensitivity

The single bouy design will work fine to detect larger waves – Like ocean waves.

Double bouy design
One big bouy houses the Arduino board, and are anchored. This bouy can have any weight. But the aim is to make a heavy stable bouy, that are unaffected by minor surface waves.

The accelerometer is placed in a very small float next to the big bouy. Just big enough to provide a water tight safe for the accelerometer. Weight about 20 g.
The small float is connected to the big bouy by a flexible horizontal cable – giving very little dampening of the vertical movement of the float.