The cannon protects 80 to 90 hectare against hail. This means an investment of 41.80 Euro per hectare with amortization over 10 years, an investment that is definitely justified for crops with a high financial balance.

The gas filling (bottles of acetylene, oxygen and nitrogen), which is good for 4 to 6 hours of shooting, costs about 500.00 Euro per year.
By way of comparison: for the Van Praet company (10 hectare), that has mainly chrysanthemum, Canna and greenhouses, a hail insurance would cost approximately 10,000.00 Euro per year.

One negative aspect are the high noise peaks generated by the cannon, up to 130 dB, measured at the source.
Rainshowers are very noise damping.
Distance in metres from the machineSound levelSound scale realized by dr. Jean Goujon
10 metres130 dBscream of pain
45 metres120 dBpop orchestra
100 metres110 dBbus or truck
150 metres98 dBbus or truck
200 metres90 dBwith open window in the street
500 metres83 dBwith open window in the street
1000 metres68 dBheavy discussion


After some years of experience and study, Marnix Van Praet achieved an improved version of the classical hail cannon. Due to climate changes and air pollution, the risk of hail damage increases.
The risk is also increased by the presence of waterways, high tension wires, highways and aviation routes.