New England Sailing Center

ASA courses are taught only at ASA schools.   Follow along with an ASA 105 Coastal Navigation lecture.  You will need navigation tools and a copy of the training chart 1210 TR and a copy of the current edition of Eldridge Tide and Pilot .  This work is based on lecture notes of the author an ASA Instructor Evaluator.  This study guide is designed to help prepare students for the class work and ASA 105 test. Students are encouraged to gain experience underway as well as in the classroom.   The author recommends that students own several books in addition to the prescribed teaching materials.  The first book is essential to the course.  The others are a logical addition to any navigator's bookshelf.     1. Eldridge  Tide and Pilot 2022 .  This book is essential for cruising the US East Coast and New England in particular.  It contains hourly current vector charts and coastal piloting tips not easily found elsewhere. ...

  9. Measurements:  Convert courses and bearings between true, magnetic, and compass.  Determine Latitude and Longitude.  Measure distance. Nautical measurements on a chart are either Angular or Linear .  Courses are angles and distances are linear.  The other vital nautical measurement is Time given in hours and minutes. Leading lights, such as this pair in Nantucket, are a guide for staying in the channel.  They may be used to check you compass deviation.  In that instance we use a line, the range, to correct an angle, compass deviation. The first measurement for navigators is True North.  The longitude lines on the chart are North/South lines.  The North Pole is an absolute.  Compasses, however, don't point at the North Pole, they point at the Magnetic Pole which shifts ever so slightly each year.  The inner rose of the compass rose printed o a chart represents the Magnetic Pole and shows the Variation from True North. Com...

  10. Check compass deviation by a transit bearing or other means. Compass deviation is how we address the magnetic field of a vessel.  Deviation may change over time as the magnetic field of the yacht changes.  This is more common for steel or wooden hulls fastened with iron than for fiberglass yachts.   There are two basic ways to check deviation.  The first and oldest is by using a table of the sun's true bearing at sunrise and sunset for a given latitude.  The other is by using a charted range (transit bearing).  We will look at the range method. Nantucket Harbor Channel Range This is similar to the range used in the example, Cleveland Ledge Channel Range. The yacht should move right to get the ranges aligned The TVMDC AW formula is used.  When D is unknown, the arithmetic result is D using TVMDC.  In such a case, TVM and C are knowns so we solve for D. Turning to Chart 1210 Tr, observe the charted "Cleveland Ledge Channel" range for...

  11. Plot a dead reckoning position on a chart using speed, time and course to steer. Deduced Reckoning or Ded Reckoning or DR ("dead" is a common misnomer) is based only on two factors:  speed and direction.  No outside influences are considered. For example:  If you proceed due North at 6 knots in one hour your DR position is 6 nautical miles due North of the starting point. Use Chart 1210Tr for this exercise.   Make a DR plot of three legs from Cleveland Ledge Light to Lone Rock at Quick's Hole, transit Quick's Hole, and finish at the entrance buoy for Menemsha Harbor, Bell "1." Assume a speed over ground of 6 knots. Mark of course Heading to next Distance to next Time to next R "14" Fl R 2.5 sec 215 deg T 12.2 nm 2 hrs 2 min BR Qk Fl G 167 deg T 2 nm 20 min G "1" Fl G 4 sec Bell 143 deg T 5.3 nm 53 min "1" Bell 19.5 nm 3h 15 m in transit Your DR plan looks something like this.  Knowing one's departure time one can estim...

Tips for preparing for the ASA 105 Coastal Navigation Exam.  The author is an ASA instructor with experience teaching the 105 course in the USA and Caribbean. References are made to products and/or companies supplying navigational products.  The author has no financial interest in either the products or companies and presents them as examples only. https://asa.com/certifications/asa-105-coastal-navigation/ Core curriculum: There are seven "Knowledge" topics and nine "Skills" topics.  Roughly speaking these are what's in your chart table and how to use those things to safely pilot a vessel along the coast.  Chapters follow the course curriculum and include descriptive material. 1. Explain the chart symbols and conventions on U.S. nautical charts in accordance with the terminology of Chart #1.               Note: An abbreviated copy of Chart #1 is found on the back of the training chart:  1210Tr. 2. Identify a source of offi...