Charles and Margo Wood - Charlie\'s Charts North to Alaska

lO

The quality of the forecasts is often debated by small boat operators whose
decisions will be based on the information given. Since forecasters tend to
formulate statements for large areas the predictions sometimes seem to have no
relevanee to any particular area, and when the inaccuracy inherent in such an
arcane art is added, it tends to give weather forecasters a poor reputation.

Canadian Coast Guard forecasts are conceded by most sailors to be slightly
more informative and to provide more data over recognizable zones than do the
U.S. foreea5ts. Conditions reported by the manned lighthouses that lie within
the area eovered are of the greatest use. This data is regularly up-dated
every few hours. It provides the clearest information as to the weather to be
expected when the reporting stations are near a vessel's location and planned
route. A list of radio weather broadcasts and reporting stations is given in
Appendix II.

The ship's barometer and the skipper's weather sense are also useful to

interpret the signs and data received. Some old and useful observations that

are wideIy applicable are:

• The weather pattern in effect today will usually be in effect tomorrow
  uniess definite signs of change are evidente


• Winds usually pick up in the forenoon and increase in the afternoon,
  tending to die down in the evening.

TIOES ANO CURRENTS

These are of great significance to anyone travelling the waters within this

guide. Tide and current tables are essentiai items of navigational informa-

tion, particularly for the times of slack water at narrow passes.

The basie tidal pattern is semi-diurnial i.e. two high tides and two low

tides per day. However, this i5 strongly affected by the moon's declination,

so that at times the tidai effect is a1most diurnial. There is a1so a marked

difference in the heights of the two high waters and the two low waters because

of the declinational effect.

The tidal range i8 high throughout this area. It varies from lO feet or

more in the southern part to 15 feet or more in the northern parto The tidal

streams flood into and ebb out of the many straits, sounds, and inIets.

The more complex tidal stream patterns occur between Vancouver Island and

the mainland. The flood enters from both ends -- Juan de Fuca in the south.

and Queen Charlotte Strait in the north. After passing through the various

channels the streams meet below Cape Mudge, in the vicinity of Middlenatch

Island. In its movement through these areas the narrowness of certain passages

combined with the high si1l5 and deep basins cause the tidal streams to pass

through at high velocities. Flood and ebb streams can reach speeds of 8 knots

at Gillard Islands, 9 knots at Dent Rapids, and 15 knots at Seymour Narrows in

Discovery Passage. Similar speeds are reached in other passes.