"The forecast was for seas 1-2 foot out to 20 miles and 2-3 foot form 20 to 60 miles.  The seas were 3-4 immediately out of the port and remained that way for about 10 miles."

Buoy 41113:

#YY  MM DD hh mm WDIR WSPD GST  WVHT   DPD   APD MWD   PRES  ATMP  WTMP  DEWP  VIS PTDY  TIDE
#yr  mo dy hr mn degT m/s  m/s     m   sec   sec degT   hPa  degC  degC  degC   mi  hPa    ft
2007 07 13 10 21  MM   MM   MM   0.6     4    MM  MM     MM    MM  27.4    MM   MM   MM    MM
2007 07 13 09 51  MM   MM   MM   0.6     8    MM  MM     MM    MM  27.4    MM   MM   MM    MM


"Then they increased to 4-6 out to 30 miles."

Buoy 41009:

2007 07 13 12 20 200  6.0  7.0   0.9     4    MM  MM 1018.2  27.8  28.5    MM   MM   MM    MM
2007 07 13 11 50 200  6.0  8.0   0.9     4    MM  MM 1017.9  27.7  28.4    MM   MM +0.7    MM
2007 07 13 11 20 210  6.0  7.0   0.9     4    MM  MM 1017.8  27.7  28.5    MM   MM   MM    MM
2007 07 13 10 50 200  6.0  7.0   0.9     4    MM  MM 1017.7  27.6  28.5    MM   MM +0.4    MM
2007 07 13 10 20 200  7.0  8.0   1.0     4    MM  MM 1017.5  27.6  28.4    MM   MM   MM    MM
2007 07 13 09 50 210  7.0  8.0   0.9     4    MM  MM 1017.3  27.7  28.4    MM   MM +0.0    MM


Buoy 41010:  

2007 07 13 13 50 200  6.0  8.0   1.2     5    MM  MM 1018.4  28.5  28.5  25.1   MM +0.6    MM
2007 07 13 13 20 200  7.0  8.0   1.2     5    MM  MM 1018.4  28.5  28.5  25.1   MM   MM    MM
2007 07 13 12 50 200  7.0  8.0   1.3     5    MM  MM 1017.9  28.5  28.6  25.2   MM +0.5    MM
2007 07 13 12 20 200  7.0  8.0   1.2     5    MM  MM 1017.9  28.4  28.6  25.3   MM   MM    MM
2007 07 13 11 50 200  7.0  8.0   1.3     5    MM  MM 1018.0  28.4  28.6  25.2   MM +0.5    MM
2007 07 13 11 20 210  6.0  7.0   1.1     5    MM  MM 1018.2  28.4  28.6  25.1   MM   MM    MM
2007 07 13 10 50 200  6.0  8.0   1.2     5    MM  MM 1017.8  28.4  28.6  25.1   MM +0.4    MM
2007 07 13 10 20 200  7.0  8.0   1.2     5    MM  MM 1017.6  28.4  28.6  25.1   MM   MM    MM
2007 07 13 09 50 220  4.0  5.0   1.1     5    MM  MM 1017.4  27.2  28.6  24.8   MM +0.0    MM
                          

The data above was pulled from the National Data Buoy Center and the wave heights (WVHT) were 0.6 meters (2 feet) near shore and 1.2 meters (4 feet) out at 120nm offshore.  In between at 41009 the seas were 1 meter (~3 feet).  

Significant wave height that is measured by the buoys is the average of the highest one third of the waves.  So this means that there will be occasional higher waves.  In fact, wave distribution studies have shown that one in 100 waves will be 1.67 times the significant wave height and one in 10 waves will be 1.25 times the significant wave height.   So in a normal wave distribution, waves in this case would be 5 feet at 41009 every 6-7 minutes and there would be about three waves at 4 feet over a two minute period.

The one piece of data that is evident which made this trip a bit on the choppy side was the dominant wave period (DPD) of 4-5 seconds, which was produced by 10-15 knot south/southwest winds.  If the wave period had been 8 seconds, the 5 foot waves would have occurred about every 13 minutes, which would have made for a much less choppy looking sea state.  Wave period really matters!  Generally when wave period comes close to being the same as the wave height (i.e. 4 feet at 4 seconds), waves are very steep and the seas are uncomfortably choppy.

There will always be problems that occur with the forecasts at times (winds can be fickle).  Also, wave theory says that there will always be higher seas than the significant wave height, so boaters need to take this into account.  Watch out for the wave period too.