Spatial variations in wave conditions at aquaculture sites

The objective of this Master Thesis is to investigate spatial variations of wave conditions
within an aquaculture site and try to determine whether spatial variations might have
an effect on the reliability of site surveys done in Norway today. To do this, acceleration
measurements of two different fish cages at a fish farm at Hosenøyan will be used to estimate the fish cage elevation responses during the period of measurement. This is done
by integrating the measured accelerations twice to estimate the position of the fish cage.
The resulting position estimates will further be compared to the incident waves recorded
during the period of the measurements, using data from a wave buoy in close vicinity of
the fish farm. The resulting data will be analysed and discussed in terms of the significant
elevation response, the elevation period and the estimated wave directions. In addition,
the validity of linear transfer functions will be investigated. The objective is to determine
whether a fish cage can be used as a wave buoy to estimate the local wave conditions at
the fish farm using linear transfer functions.
The main findings of this Master Thesis are that spatial variations seem to be present,
even though the differences between the two fish cages are relatively small. However
the differences seem to grow larger as the surrounding conditions grows harsher, pointing
towards that spatial variations may be significant for fish farms at more exposed locations.
As for using a fish cage as a wave buoy, the analysis showed no indication that it could
be done by applying linear transfer functions. However, for both the estimation of the
elevation response of the two fish cages and for the linear transfer function analysis, many
large sources of error affected the results, indicating that the results of this thesis may
not be reliable themselves.