  We present the analysis of a CCD survey of 31 nearby (<= 110 Mpc) edge-on
spiral galaxies. The three-dimensional one-component best fit models provide
their disk-scalelengths h and for the first time their disk cut-off radii
R_{co}. We confirm for this sample the existence of such sharp truncations, and
find a significantly lower mean value of the distance independent ratio
R_{co}/h =2.9 +- 0.7 than the standard value of 4.5 often used in the
literature. Our data show no correlation of these parameters with Hubble type,
whereas we report a correlation between R_{co}/h and the distance based
scalelength in linear units. Compared to the Milky Way we find only lower
values of R_{co}/h, explained either by possible selection effects or by the
completely different techniques used. We discuss our data in respect to present
models for the origin of the cut-off radii, either as a relict of the galaxy
formation process, or as an evolutionary phenomenon.
