+

Introduction to Coastal NavigationUniversity of Texas Sailing Club

+Disclaimer

I am not a certified by ASA, US Sailing, USCG or anyone else to teach this class nor will this class count towards an ASA, US Sailing or USCG certificate.

The purpose of this class to inform and familiarize

+Outline Before sailing

Reading charts Understanding symbols Planning a route

While sailing Lights & Buoys GPS Visual (line of sight) positioning Dead reckoning Basic idea of celestial navigation Right of way

+Google Maps

Houston Yacht Club

Kemah

Houston

+Google EarthYou try to be smart & use a satellite image…

+NOAA Chart

+Planning a course

Shal

low

w

ater

Ship Channel

Ship Channel

Shallow w

ater

Narrow Channel

+Planning a course

+Houston Yacht Club

Google Earth NOAA Chart

What additional information is given?

+Kemah

Google Map NOAA Chart

There’s a channel?

+NOAA 11327 – Galveston Bayhttp://www.charts.noaa.gov/InteractiveCatalog/nrnc.shtml

+Understanding Chart SymbolsCompass Rose

True (geographic north)

Magnetic north

Correction factor

+True vs Magnetic North

Source: coastalnavigation.com/

+Understanding Chart Symbols

Fl 4s 30ft Priv = Flashing every 4 seconds 30 ft above mean tide. Private light

Q G 23ft “1” = Quick flashing green 23 ft above mean tide. Painted “1”. Private light

F R 12ft Priv = Fixed red 12 ft above mean tide. Private light

Fl R 6s 17ft 4M “2” Ra Ref = Flashing red every 6 seconds 17 ft above mean tide visible for 4 miles. Painted “2”. Radar reflective

G “1” Ra Ref = Green buoy painted “1”. Radar reflective

LIGHTS

+Understanding Chart SymbolsOBSTRUCTIONS

Visible from surface Submerged

Partly Submerged Wreck All sorts of fun stuff

+Understanding Chart SymbolsDEPTH

Marsh & Shallows Reef

Dumping area from dregging Depth in feet (US maps only)

+Plotting a Position Fix (PF)Using several reference points to determine your location on a chart.

+Plotting a visual fixAt 10:40PM, You see a red light flashing every 6 seconds at 217 degrees and a green light flashing every 6 seconds at 137 degrees according to your magnetic compass. Where are you?

20 minutes later, the same red light is at 232 degrees and the green light is at 147 degrees. How fast are you traveling?

You continue sailing the same heading. 20 minutes later, the red light is now at 250 degrees and the green light is at 160 degrees. What happened?

2300

2240

2320

2320

+Why is this relevant?

You plan to sail the following course from Kemah to the Houston Yacht Club. How do you know when to turn (without being glued to your GPS)?For example:• Sail along ship channel

until past R “2” and G “1”

• Turn to heading 030 on your compass; pointed at the G Radar Reflective Mark (bad example)

• When the 6s Green is on the beam, turn to heading 320

• Once the 2.5s Green is on the beam, turn to heading 270

Hea

ding

030

Heading 320

+A running fixWhen you only recognize one object

+NOAA 13233 – Martha’s VineyardBelow Cap Cod in Massachusetts. (beautiful sailing, check it out at some point)

+Plotting a Running Fix (R Fix)Using a single reference point and your assumed course to determine your position

+Running FixIt’s hazy out, so you can only see Gay Head Light. You are sailing a course of 270 degrees magnetic at 6 knots.

• At noon, you sight gay head at 220 degrees.

• At 12:10, it is at 180 degrees.

• At 12:20, it is at 140 degrees.

Plot your course

• Now you change course to 180 degrees. At 12:30, Gay Head is now at 110 degrees.

???

R Fix 1210

R Fix 1220

R Fix 1230

+So, what?When plotting a course, you need at least one reference point if you keep track of your course

Why? This allows you to notice currents, tides and wind.

• What would have happened if the course was pushed east instead of west?

R Fix 1210

R Fix 1220

R Fix 1230 R Fix 1230

+Distance to the Horizon On the ocean:

Where d is in statute miles and h is in feet So if you fall in the water, you can see about a mile In a small boat, where your head is 3 feet off the water, two

miles

To an elevated coast

So a 10 foot dune is visible 6 miles out to sea from 3 feet above the water

+Celestial NavigationHow stars can guide you

+Basic IdeaThe moon, sun and each star is directly overhead on some point of the planet. Call this point A. (technically the ephemeral point)

By measuring the angular distance from directly over you to the object, you know how far away from point A you are.

It is really hard to accurately measure direction to the object, so you measure 2+ objects.

There is a point on the sphere where these distances ‘intersect’. This is your Celestial Fix.

Source: tjradcliffe.com

+

In 3DYou get a Circle of Position, but if you zoom in, it can be approximates as a Line of Position.

Two or more of these intersect to give you your position on the globe.

Source: wavetothewind.com/

Source: onboardintelligence.com/

+

How do you measure angles?With a sextant

• Originally developed by Sir Isaac Newton in the late 1600s (as an octant)

• Refined to it’s current form in the 1757

Required accurate time keeping – lead to the development of the chronograph (1816)

+

Plotting the fixThe more stars you measure, the more accurate your fix becomes (hopefully).

A lot of spherical trigonometry (or tables in the form of the Nautical Almanac) is needed. See me offline if you want more information.

+How GPS worksSimply the intersection of spheres of position to give you (x,y,z)

Source: education.nationalgeographic.com/

+Navigation Lights

+Right of Way

Who yields?

Horns

+Do you need to change course?

If you see green, ALL CLEAR Just keep an eye on the ship – he may not see you

If you see red, BE READY TO YIELD Determine if a collision may occur (compass bearings)

If relative compass bearing is approaching your heading, YIELD

If go away from your heading, ALL CLEAR

If you see white, If it is the stern light, ALL CLEAR If a mast head light, FIND THE RED OR GREEN

Make any course changes APPARENT

Is a collision imminent?

+

Channel MarkersKeep right in virtually all marked shipping channels in the US unless otherwise noted.

• ALWAYS check the chart before heading into a channel

• NEVER attempt to sail along an active shipping channel

• CHECK tide information before entering a narrow channel• ENSURE your boat can go

FAST enough

Source: watercraft.ohiodnr.gov/

+Take aways

Always familiarize yourself with a new body of water. What looks sailable on Google Earth may not be so. http://www.charts.noaa.gov/InteractiveCatalog/nrnc.shtml

Things disappear behind the horizon!

A swimmer can see about a mile A small sailboat can see about two miles (or a sand dune on

a beach 5 miles away)

A boat with its port side to you has the right of way. You have the right of way if you see its starboard side.

If you remember nothing else…