50 seamanship secrets
“Your Call, Skipper”
You’re the skipper or most knowledgeable crewmember in each
of the following situations. What actions would you take?- You are at the chandlery and need to purchase a chart showing
the best detail of San Francisco Bay. The vendor has three charts for
that area with scales of 1:125,000, 1:80,000, and 1:40,000. Which do
you buy, and why? - Before checking your compass for deviation, what two things must
you do? - You arrive at a sea buoy and want to know the distance to the turn
into the main channel. You measure on the latitude scale 3'22". What
is the distance to the channel just ahead? - While underway in a narrow channel, you lose engine power and
must take immediate action to keep from grounding. Where do you
look to find an emergency anchoring spot? - Which two places would you look to find the variation at your loca-
tion on any chart used throughout the world?
Answers - A scale of 1:40,000. The second number represents the magnifica-
tion necessary to show the same relative size of landmass on earth.
The smaller the number, the greater the detail. - Remove magnetic materials that you are wearing. Stand in an
area not influenced by metal (for instance, a metal awning). Ener-
gize all equipment you routinely use underway to simulate actual
conditions. - The distance is 3.4 nautical miles. Divide seconds by 6 and round
off. - Aim for white pockets of deeper water on the channel edges. Better
yet, mark these ahead of time when annotating your chart. - In coastal or piloting waters, look in the center of the closest compass
rose. On coastal or offshore passages, look for the closest dashed or
solid magenta isogonic curve. Find the variation written somewhere
on top of the line.