Hindcast or Wave Reanalysis Data Bases (WRDB) have become a powerful tool for the design of offshore and coastal structures, since they offer important advantages for the statistical characterization of extreme events (continuous time series, good spatial coverage, constant time span, homogeneous forcing, > 40 year long time series). However, WRDB are affected by several limitations that must be addressed prior to their use (they are not quantitatively perfect; high-frequency information is not included in global wind reanalysis models). In addition, the selection of a given extreme value model is also an important issue that must be conveniently analyzed. The objective of this work is to describe a complete methodology able to cope with the problems derived from the use of WRDB, specially for extreme value analysis and long term design. We pay special emphasis to: i) the high frequency noise or peaks of the time series, and ii) the extreme value statistical model. The methodology is illustrated with examples applied to the port of Barcelona (Spain).