IndicesThe 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 machine||Sound level||Sound scale realized by dr. Jean Goujon|
|10 metres||130 dB||scream of pain|
|45 metres||120 dB||pop orchestra|
|100 metres||110 dB||bus or truck|
|150 metres||98 dB||bus or truck|
|200 metres||90 dB||with open window in the street|
|500 metres||83 dB||with open window in the street|
|1000 metres||68 dB||heavy 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.