piloting tips and techniques 97
“Your Call, Skipper”You’re the skipper or most knowledgeable crewmember in each of
the following situations. What actions would you take?- Fog shrouds your boat. The GPS is on the blink, but your fathometer
seems to be working. What three steps would you take before turning
and heading for land? - Your chart shows an 80-foot light on a high cliff dead ahead. The
charted nominal range is 12 miles. Your HE is 9 feet. How would you
set up the chart to make landfall? - A dangerous coral reef lies 2 miles ahead just off your starboard
bow. You need to make a quick decision and turn to the left. Swift
currents make the reef a lee shore. How many degrees must you alter
course to clear the reef by 2.5 miles? - You need to beat to windward and pass a mile-long stretch of dan-
gerous shoals to starboard. The skipper has a new GPS unit, no manual,
and not a clue as to how to use it. You plot a quick GPS grid highway
to clear the shoal. How would you explain to the skipper the method
for using this grid highway? - On a power vessel traveling at 22 knots, what is the minimum
practical size you should make a GPS plotting grid?
Answers - First, study the chart and look for a contour curve running along
the coast 2 to 3 miles on either side of the destination. Second, correct
your depth sounder to the charted depth (using transducer depth and
present height of tide information). Third, aim well upwind or upcurrent
of the destination. - Measure two arcs from the light at 12 miles and 14 miles. Calculate
the time to both ranges, and set the GPS alarm. - Using the Rule of 60, and knowing that your DO is 2.5 and your DA is 2,
you determine that you need to alter course 75 degrees to the left:
(60 x 2.5) ÷ 2 = 75 - Sail close-hauled until you reach the highway meridian closer to
the hazard, then come about and sail until you reach the highway
meridian on the opposite side. Continue this procedure until the boat
clears the shoal at the GPS latitude exit gate. - It should be 11 miles, or half the speed of advance.