At sea. Lat. [Latitude] 51.28 N. [North] Lon. [Longitude] 17.24 W. [West]
Run 344 m. 348
Ther. [Thermometer] THURS. [Thursday] OCT. 7, 1909 "By noon the sea went very high indeed, and our ship rode forecastle in, shipped several seas, and we thought once or twice our anchor had come home; [...]."

What does "shipped several seas" mean?

Source: Robinson Crusoe [October 7, 1909] Wea. [Weather] 
Stormy
  Cloudy with strong westerly winds
and high seas. The wind blew a full
gale last night for an hour or more
when the Ivernia shipped several seas
which half inundated some of the cabins.
The ship behaved well & was very
steady yet more than one half of the
passengers were ill to-day. None of the
ladies in our party left their staterooms.
& the decks were deserted in afternoon.
I spent most of day in smoking
room talking with various passengers
especially with Curtis Guild, Mr. Kidder
& Charles Kettell. Kidder reports seeing
a flock of about 20 Shearwaters of
some kind & several Mother Carey's.
I saw only one bird - a Manx
Shearwater soon after breakfast. 

At sea - Lat. [Latitude] 50.56 N. [North] Lon [Longitude] 26.07 W. [West]
Run 329 m.
Ther. [Thermometer] FRI. [Friday] OCT. 8, 1909 [October 8, 1909] Wea. [Weather]
Stormy
A wild day, cloudy, raining hard at
times with rough sea & a full gale
of wind from S.W. [Southwest]. About 75% of
all the passengers, including all the ladies
of our party except Miss Allyn, kept 
to their staterooms. One of the
steerage passengers, a young Irish
woman with 2 children, burst a blood 
vessel from excessive vomiting & died at
8 A.M. The steamer was stopped
at 4 P.M. when I saw the coffin
lowered into the sea.
  I spent nearly the entire day in
the smoking room talking with
the passengers chiefly with Kidder
& Curtis Guild. The latter is a delightful
man & a rare raconteur.
No birds of any kind reported. I saw
2 small school of porpoises sporting
in the rough sea.