Page 220 - NAVAL SCIENCE 3 TEXTBOOK

226 NAVAL SKILLS

by drawing a line from the pole e to the end of the relative speed true wind, gh'en the ship's true course and speed ilnd the relative
vector(see the illustration on prvious Pi.lgC). wind. given the ship's true course and speed and the true wind.
Thc bearing of the vector elll is the true coursc-040° in this To determine true wind all the maneuvering bOilrd, a vector
case-and its length, measured by the dividers along the 3: 1 scale, representing the direction toward which the relative wind is blow-
is the spced-141f2 knots. ing and its speed (determined by a vessel's anemometer) is plotted
from the head of the ship's true course and speed vector. Again, for
consistency the same speed sGlle is lIsed throughout; thc head of
The Wind Problem the relatiye wind vector is labeled with a lower case 11', so that vec-
Since the l-e/ntil'e wituf that a person feels across a vessel's deck is the tor nv is the relative wind.
result of the wind created by the Illotion of the vessel plus the actual The true wind \'ector ew is then formed by drawing 3line from
or fme wi/ui, which can both be represented by vectors Oil a vector (' at the pole to the head of the relativc wind vcctor 1'. Since winds
diagnll11. the maneuvering board can be used both to determine the are defined according to the direction from which they are blowing,

" ..... M A N E UVERING B O ARD
1:1 "
• • • "
" "
• "

" •
» •
• ..

• "
• .-

" • ,- -,
n
"
• • ~ ,- . . ) . \ -, s
• " -.
,-
• ,,-
, ,
,
•
, ..
, ,
,
•
• •
• •
• • --_._- '''. ~ .. ~ ... , ..
......... __ .... _ ... _-
,
.
_'''' ....... _ ... ·~ .. ,.u"
.-......... --" . -~ " -"'-" '" ---
=::;:'-:::::';.::::.;.-::
::::::.---=.=.:-:,:-.~": ~-:-.:.':.:!::.::.-;.:::'; '--....:_....:_~I....:'~' ~1~1~1~1I'.:!2!.:.! ::H':.! --=~! .:!~!.:.!~!!'!.!.:.! ~!!~!;! ~_I~! ~I.~II~I!.I....!.~I ==:.::
:::==-.::=..::.~=-:
_._---............ __ ._-
• C.":.'"
- • ••••••
. ........ _
=.!=:..",:::-..:'~" " '"
...... __ ........ - .. " ........... "'-co ~""'_'U« ___ ''''1' _ .. -.., ..... ...-_ ... , .. ,_.",:",
-
---~-~~-~~~~. ~.~.~~~~~'~.~.-.~~.~' -. ~
~ .... IUU __
....... , .. , '--' ,._'"
-... _..-, ............... ,' ..
"'_ ..... _" ...
... , ... --.,."' . ...,...,...-
"'~I, .. I"'I"""''''''-''''''''''
.. " " .....
• ..-.... "' .c,,'
'-"""-"""""
Completed maneuvering board plot to find the direction and speed of the true wind (the vector ew).