182 seamanship secrets
- Battery compartments. Batteries can release deadly hydrogen gas and must
be secured in a ventilated compartment. Check each battery as a separate
component. Each battery needs its own cover to prevent accidental arcing
across the terminals from dropped metal items. Each battery also needs a
tie-down strap to keep it from shift ing or rolling around. - Th rough-hull integrity. Our last component gets forgotten as oft en as the
wheel quadrant system. Check every handle on every seacock on every
through-hull. You must be able to close any seacock with minimum eff ort.
Move the handle from open (parallel to the hose) to closed (perpendicular
to the hose) and back to open. If the handle is frozen, a gentle tap with a
hammer or mallet oft en encourages smooth operation. Check scupper, sink,
shower, head, and engine seacocks. Examine the hoses and stainless steel
clamps at the top of each seacock. A tapered wooden plug should be lashed
to each seacock with easily broken twine. If a seacock hose fails, you can
drive the plug into the seacock bore. (For more on fl ooding, see “Handling
Flooding Emergencies with M.A.T.E.,” page 280, in Chapter 13.)
Clearing Up the Mystery of Apparent Wind
Sails operate in apparent wind, which is a combination of your boat’s speed and
the true wind (the wind you experience when your boat is not moving). To sail
effi ciently, sails must be trimmed to the apparent wind. Knowing this gives racing
sailors an edge over their competition, and it enables cruising sailors to reach their
destinations much faster. Let’s break the mystery of apparent wind into four easy
pieces.
Boatspeed changes. Picture yourself standing outdoors with the wind blow-
ing against the left side of your face. Begin walking, and increase your pace until
you reach jogging speed. Th en slow down gradually until you’re standing still.
What did you notice about the wind? When standing still, you felt the true
wind against the left side of your face. As you increased your speed to a jog, the
wind “appeared” to move toward the front of your face. Of course, the wind never
really moved; rather, your own forward motion, or speed, caused this apparent
wind. Remember these two facts about apparent wind.
If boatspeed increases, apparent wind moves toward the bow (or the front
of your face).
If boatspeed decreases, apparent wind moves away from the bow (or away
from the front of your face).
Boat course changes. If two vehicles traveling at 25 mph were to collide,
the drivers would feel an impact of 50 mph. Similarly, when we are sailing
close-hauled (as close to the wind as possible), our boat speed and the true wind
speed are additive, and the apparent wind feels stronger than the true wind.