©2013 Avis Rent A Car System, LLC 100657-01
Terms and Conditions: $30 off weekly rental coupon valid on a compact (group B) and above, excluding Specialty (group X) vehicles. Dollars of f applies
to the time and mileage charges only on a minimum five-day weekly rental period. Taxes, concession recovery fees, vehicle license recovery fee and
customer facility charges may apply and are extra. Optional products such as LDW ($29.99/day or less) and refueling are extra. One coupon per rental.
An advance reservation is required. May not be used in conjunction with any other coupon, promotion or offer. Coupon valid at participating Avis
locations in the contiguous U.S. and Canada. Offer subjec t to vehicle availabilit y at time of reservation and may not be available on some rates at some times.
Dollars off coupons presented/entered during reservation are calculated at time of reservation. Renter must meet Avis age, driver and credit requirements.
Minimum age may vary by location. An additional daily surcharge may apply for renters under 25 years old. Rental must begin by 3/31/2014.
Boating is your passion. Getting there should be
fun, too. Arrive in comfort and style (on land) and
save up to 25%, plus $30 off a weekly rental.
Make your reservation at avis.com/boatus or by
calling 1-800-225-7094. Use AWD A637200
along with coupon MUWA090.
For a complete comparison of Class
A and B transceivers, see this article
This information can be displayed on an iPad
or computer aboard if you have an Internet
connection, and this has become the “poor
man’s” AIS for those who do not want to
install a Class A or B unit. Be aware that
if you do have a Class A or B unit and are
broadcasting your information, anyone can
go on those sites and search by vessel name
to find your last reported position and, in
some cases, your track, including course and
speed, to that position. If you prefer privacy,
purchase a Class B “receive-only” unit.
If you navigate in areas with a lot of AIS-equipped vessels, you can sometimes get an
annoying number of collision alarms. To minimize this problem, it is very useful to buy an
AIS with three types of collision filters:
■ CPA distance – The distance to the closest
point of approach
■ TCPA – The time to the closest point
■ Target speed – How quickly the other ves-
sel is moving
If you’re sailing in open, uncrowded
waters, set the minimum CPA distance to
around 1 nautical mile and the TCPA to
around 30 minutes. The collision alarm
won’t go off until another vessel is within 30
minutes of passing within 1 nautical mile of
your position, giving you plenty of warning
that a vessel is crossing your track, and time
to maneuver, while keeping the number of
false alarms to a minimum. If you’re navi-
gating in much more crowded waters, you
might set the minimum CPA to 0.2 nm and
then TCPA to 10 minutes.
In most situations, you’ll want to leave
the target-speed filter set at zero, so the
alarm will sound if there’s a stopped or very
slow-moving vessel in front of you on the
water (like a fisherman picking up a pot, or
a ship waiting for a pilot). However, if you’re
navigating around marinas or docks where a
number of stationary vessels have their AIS
turned on, you can set a minimum target
speed filter to something like 0.2 knots to
filter out alarms for the docked/stopped ves-
sels. Note: It’s polite to other AIS users to
turn off your AIS transceiver when docked
This summer, thanks to our AIS, I passed
through New York Harbor singlehanded
with no drama whatsoever, and with complete awareness of all the commercial vessels around me. We’ve found the AIS to be
particularly useful in high-traffic areas like
that one and in heavy fog. Most ships these
days transmit AIS, though we’ve seen the
occasional one that didn’t (typically in those
cases, it’s broken).
Useful as AIS is, don’t let yourself be
lulled into thinking that you’re seeing all the
vessels in your vicinity. A large percentage
of recreational and fishing vessels are not
equipped with AIS transmitters.
AIS is another, albeit very helpful, aid to
navigation. Never rely on one single aid to
navigation. Keep using your eyes and the
radar to be sure you don’t find yourself in a
close encounter you didn’t see coming.
Evans Starzinger has completed two circumnavigations under sail, and has written technical
articles on a broad range of subjects. He’s just
returned to the Chesapeake Bay after solo sailing in Maine for the summer.