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Basic Navigation Skills

Navigating the inland waters of the Pacific Northwest demands some basic navigational skills.  Your skill level will determine the areas that are safe for you to visit.  At the very least, you must be able to understand and use paper charts, cruising guides, depth sounder, VHF radio, and a maritime compass.  Beyond that, your cruising will be much more enjoyable and flexible if you can use a GPS Chartplotter, radar, and the other modern electronic navigation aids.

Charts, GPS, other vessels:   There are not a lot of tricky navigation situations in the P.N.W.  but there are many rocks, reefs, shoals and other obstacles.  Strong currents and choppy conditions exist in many areas.  Constant attention and situational awareness is required.

1.    There are many rocks and reefs to avoid.  Almost all are clearly charted but if you don’t keep track of where you are, even the best charts or GPS systems won’t keep you safe.  Pay attention.

2.    Electronic navigation equipment is wonderful but you are only one electron away from being in trouble.  Always have proper paper charts and know how to use them.  We have a chartplotter at the helm and its always on but we never leave without the proper paper chart in full view of the helm.  We plot courses on our paper charts and we constantly make reference to the paper chart while we are underway.

3.    Charts for Pacific N.W. cruising areas are available in large “chartbooks”.  Puget sound, the San Juans, Gulf Islands, and Desolation Sound all have such books.  The Sunshine Coast has a set of “strip charts” that are easy to use.  These sets are not expensive.  There is no excuse for going cruising without paper charts.

4.    GPS chartplotters are wonderful but they can be wrong.  They are only as good as the underlying chart datum.  We have observed several situations where our GPS showed us traversing land.  Also, do not “over zoom” your chartplotter.  Zooming in past the data limits of the chart can yield deceptive visual results and make it appears you can navigate a narrow channel or around an obstruction when its not actually possible.

5.    GPS chartplotters can be highly accurate.  If you set a waypoint at the location of a buoy or submerged rock you may run right into it.  A few years ago In the Broughton Islands a beautiful new trawler ran smack into a nasty rock (set as a waypoint) because the skipper thought the GPS would not bring him so close. Additionally, some charted obstructions were given locations on the planet long before GPS was available and the charted latitude and longitude are not totally accurate.

6.    Keep track of other boats around you.  More and more vessels have auto-pilots using GPS to go from one waypoint to another.  Sometimes there will be no one at the wheel or even on watch.  Despite the rules of the road you may need to yield to avoid a collision with a boat motoring along with no one paying attention.

7.    There are big ships in the P.N.W.  There are designated shipping lanes and traffic separation lanes.  Small boats should stay out of the traffic separation lanes.  The lanes are clearly designated on the charts.  They exist in Puget Sound, Haro Strait, Georgia Strait, the Juan de Fuca Strait, Johnstone Strait, and other areas.  When you cross a traffic lane try to do so at a right angle.  Keep track of the ships around you and yield the right of way whenever possible.  Ships are huge and cruising boats are small.  Don’t play games.

8.    There are huge ferries in the San Juans and Gulf Islands and they move fast.  There are too many cases of ferries obliterating cruising boats, particularly in Canada.  When you are in open areas give way to the ferries and watch for the large wakes.  When you are near the terminals, keep track of who is coming and going and stay out of the way.

Tides:  Tides in the P.N.W. can run 10′ – 20′.  There are usually two high tides each day and two low tides each day.  Some times of the year the tidal differences can be quite extreme.

1.  In the San Juan Islands, the Gulf Islands, and Puget Sound the tides are not especially extreme.  Tidal differences rarely exceed 14′ from high to low.  But differences of 10′ are common.  That means you may be anchored or moored in 20′ of water at high tide and just 10′ of water at low tide.  This can get your attention, particularly on a sailboat swinging around on the anchor.

2.    North of Vancouver in Desolation Sound and the Broughton Islands tidal extremes can be 15′ – 20”.  This means you must pay close attention to the highs and lows each day.

3.    Cruising in the P.N.W. demands that you have a tide book, preferably one that has the tides and currents for all the reporting stations and the correction formulas for many other areas.  These books are available at all marine stores and chandlerys.  Buy one before you go cruising and learn how to use it.

4.    When you anchor make a note of the time and depth and calculate the changes in depth that will occur.  You may find it will be too shallow to stay for 24 hours.

5.    Big tides mean strong currents.  Areas that usually have strong currents will be worse.  If the wind will be blowing against the current this can mean choppy and sloppy water with uncomfortable conditions.  Big tides will also mean unpleasant (and even dangerous) conditions in areas where “tide rips” form.  Check your charts when planning your destination and course and avoid these areas when the current is strongest or when winds are a factor.

6.    Some docks and marinas have shallow water at low tides.  For example, the state park docks in Fossil Bay at Sucia Island have just 4′ of depth at zero tide.  Portions of Islander Resort Marina in Fisherman’s Bay have less than 6′ of depth at zero tide.  The entry to Fisherman’s Bay has only about 4′ of depth at zero tide.  You must be aware of the minimum depth of areas you plan to visit.

 Currents:  Many areas in the P.N.W. have strong currents that affect our cruising choices.  When dealing with currents, timing is everything.  Even a 1-2 knot current running against you rather than with you will dramatically affect your time of travel and fuel economy.  For example, if you are planning to go 56 nautical miles and your boat cruises at 7 knots, with no current it will take you 8 hours.  With a favorable one knot current it will take just 7 hours.  With an unfavorable 1 knot current it will take 9.3 hours.  Just on knot of current can make your time vary from 7 hours to 9.3 hours.  If you boat uses 5 gallons of fuel per hour, the difference in cost may be as much as $50.00.

1.    When choosing a destination check your charts and current tables.  There are areas that are only safe at or near slack water.  Some of the best known are Dodd Narrows (approaching Nanaimo), Malibu Rapids (approaching Princess Louisa), Cattle Pass (at the south end of San Juan Channel), Deception Pass (at the north end of Whidbey Island), and Active Pass (between Mayne and Galiano Islands).  These areas can be dangerous when the current is running.  In other cases, running against the current may not be hazardous but it can add hours to your transit time.

2.    Check weather conditions and wind forecasts.  In many areas, wind blowing against the current can change benign conditions to unpleasant steep and choppy waves that will be very unpleasant.  This is especially true in areas like Rosario Strait, Haro Strait, Georgia Strait, and Johnstone Strait.

3.    Currents can create unpleasant and even dangerous “tide rip” conditions when flowing water intersects with stationary water.  For example, at the north end of Admiralty Inlet the waters of Puget Sound flow into the Strait of Juan de Fuca.  The area off Point Wilson can have violent tide rips with steep choopy waves 5′-10′ high bashing around in every direction.

4.    Paper charts indicate the direction and speed of currents in some areas but not very many.  Additionally, the paper charts give no indication of the times of strong and weak currents.  You cannot accurately discern current strengths just by the high and low tide although you can make a decent guess.  Generally, currents will continue to run for 1 – 2 hours after the turn of a tide