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					Low Visibility - Sound Signal Tips That Could Save Your Life!
You may think that low visibility applies to fog bound boats deep in the cold waters of New England,
northern California or other foggy areas. But did you know that even in the Caribbean, you can have
similar conditions that require immediate action? Keep your crew safe and sound when you know the
lights and signals for sailing in tough conditions!

Are you In or Near Low Visibility?

Fog, haze, rain, sleet, snow, sand, squalls, or even in
heavy weather conditions with heavy spray all
constitute low visibility. Look at low visibility from the
other vessel's point of view. If they are unable to detect
you, then you are vulnerable to collision.

How can you best make your presence known to all
other vessels around you? Surround your vessel with a
"cone of light and sound" protection.

Indeed, that's just what the Navigation Rules require
you to do. And after all, it's for your protection and the
protection of the other vessels out there that you may
not be aware of.

Remember this; not all vessels have AIS and not all
vessels have radios. Nor do they all have radar. Some
watchstanders are not alert, fail to make visual scans,
and rely too much on electronic alarms to warn them of       Your crew will look to you to keep them safe when in or
danger. And this includes professional licensed              near an area of low visibility. Know your Navigation
                                                             Rules so that you can sound the correct signals and
skippers too! In addition they may never pick you up on      show the proper lights. (photo courtesy of Sailing Vessel
radar--and here's why...                                     "Charbonneau")

Sailboats make poor radar targets. Hulls are low to the water. Masts, booms, and sails give poor reflective
signal returns. Radar reflectors might do well in tests, but atmospheric conditions, heeling, and sea state
can give spotty radar returns.

Sea and rain clutter on a radar can look like hundreds of targets. In the end, you must make great effort to
make your vessel "visible" by other means, such as proper navigation lights and sound signals.

When to Sound Low Visibility Signals?

Imagine that you are in San Francisco Bay on a clear and sunny sailing day. Where you are sailing,
visibility could not be better. But a half mile ahead, you see a fog bank. You will sail around the fog bank
to avoid it.

Yet, the Navigation Rules that govern collision avoidance require you to sound low visibility signals
(sometimes called "fog signals") right away. You want to warn anyone underway inside the fog bank of
your presence. Not by radiotelephone. But by the proper signal for a sailing vessel underway (or--if under
power--you are considered a power-driven vessel) in or near an area of low visibility.
Sailing or Under Power?
What lights and sound signals are you required to use? This
depends on whether you are under sail alone or under power           In or near an area of restricted visibility,
(which includes under sail and power--or motor-sailing). If you whether day or night, the signals prescribed
are under power, the Rules consider you to be a power-          in this Rule shall be used...
driven vessel. Power-driven vessels give different signals and                          -- Navigation Rule 35
show additional lights (see table below).

There have been arguments that while charging batteries with sails hoisted and the engine on but the
shifter not engaged (in forward or reverse propulsion), you were still a sailing vessel.

But consider the point of view of another vessel that sees your exhaust spitting water. The other vessel
could assume that you are now under power, and no longer just under sail. In the event of a collision, you
might have a tough time proving in Admiralty court that you were under sail alone if you have your engine

Lights and Signals You Need to Know

Use a hand held horn or air-canister device to give sound signals. The Rules define blast duration as
"prolonged", which means 4 to 6 seconds and "short" which means 1 second.

Give combinations of blasts in succession. For example, if you are required to sound one prolonged and
two short blasts, you would sound a prolonged blast for four to six seconds immediately followed by two
short blasts of about one second duration each.

Underway making way means you are being propelled through the water by some means--sail, engine,
oars. Underway not making way means you are stopped and drifting.

Look over this table of sound signals and lighting requirements for vessels under sail or power. Note what
you must do when you operate your sailboat under sail and power or power alone.
*NOTE: You are not required to sound the bell at anchor if you are less than 12 meters (39.4 feet) in
length. But you must give some signal at intervals of not more than 2 minutes. The signal must be unique
and not used anywhere else in the Rules. One suggestion is to sound 1 short-1 prolonged-1 short blast
every two minutes to warn others of your position.

Nor are you required to sound the bell at anchor in a designated anchorage or mooring area. Designated
means an area specifically set aside by authorities for anchored vessels (i.e., a mooring field).

Captain John's Sailing Tip
Slow down in or near an area of low visibility. Adjust your speed so that you can stop in
the prevailing conditions in plenty of time to avoid collision with another vessel.


Put these sailing tips into play aboard your sailboat when sailing in or near restricted visibility. Keep your
day sailing, cruising and voyaging sailing crews safe and sound--wherever you choose to cruise!

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