84 seamanship secrets
- Measure the distance to the contour curve. Estimate the speed you
will use. - Determine the time to the contour curve. For example, if the distance
is 3 miles and your boatspeed is 5 knots, it should take you 36 minutes.
If you make this calculation at 0900, you should arrive at 0936. - Mark the contour curve with your estimated time of arrival. In our
example, we would label it 0936. - Watch your depth sounder during the transit. As soon as your depth
sounder (as corrected for transducer depth and height of tide; see earlier
in this chapter) reads the sounding of the contour curve (which should
be at the approximate time you indicated), turn toward the destination. - Measure the distance from this turning point to the destination,
estimate your speed, and calculate a new time of arrival at the harbor
entrance.
SEA-CRET TIPS FOR LONGSHORE
PILOTING LANDFALLS
X Correct your fathometer for tide and transducer depth to match
the charted datum (MLLW or LAT; see Chapter 1).
X Lay your track to the upwind or upcurrent side of the destination.
That way, you’ll have a fair wind and sea at your back when you make
your turn.
How to Avoid Hazards with Danger Bearings
Imagine that a dangerous rock-strewn island lies ahead to starboard. The
currents in this area are notorious for sweeping small craft down onto the
shoal. We need to make the anchorage on the other side before sunset. How
can we do this easily and safely?
When approaching an area with navigational hazards, you can stay safe
by plotting bearings to a single object. This danger bearing is a reference point
to tell us whether we are passing safely by the hazard.
Choose a charted object that lies between you and the danger and on the
side of the danger on which you wish to pass. An alternative is to take a tangent
bearing to the steep sides of an island or cliff s that lie ahead of the danger. Always
check the chart before you make a decision. Th e accompanying illustration and
instructions demonstrate using a danger bearing to pass the hazard safely.