| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 796.1 | vector sum | MSCSSE::BERENS | Alan Berens | Fri Apr 15 1988 15:30 | 17 |
| The wind speed and direction measured by a masthead wind instrument are
really the apparent wind speed and direction. Apparent wind is the
vector sum of the true wind and the wind created by the movement of the
boat. The determine the true wind speed from the apparent wind speed,
you need to know three things:
the apparent wind speed A
the speed of the boat B
and the angle C between the direction the boat is moving and the
direction of the apparent wind (C is 180 degrees for the wind
dead astern and 0 degrees with the wind dead ahead)
True wind speed = SQRT(A*A + B*B - 2*A*B*COS(C))
|
| 796.2 | | XCUSME::OPERATOR | | Sat Apr 16 1988 02:15 | 10 |
| If you know the apparent wind speed and direction and boat speed,
you can use true wind/apparent wind conversion tables. Chapman's
book on piloting has these. Chapman's also has the formulas so
you can use a calculator to figure true wind.
If you get an electronic wind speed/direction indicator, some can
take input from the knot meter and figure true wind for you.
paul..
|
| 796.3 | currents, too | CADSYS::SCHUMANN | | Tue Apr 19 1988 11:34 | 5 |
| If you are fussy about accuracy, you may also want to figure in the effect of
the current you are operating in.
--RS
|
| 796.4 | my grease...for all seasons | GRAMPS::WCLARK | Walt Clark | Tue Apr 19 1988 18:17 | 12 |
| I have been using Amzoil wheel bearing lube in the rudder bearing
box for a couple years. It is a synthetic. It also does not seem
to wash out, or break down in the presence of salt water. I wont
tell you how long I go between teardown and lube jobs on the winches
with the same grease.
It is THE best lube I have ever found, and have yet to use it and
not notice a significant reduction in friction (soon after using
it and over the long haul).
Walt
|