The cheapest way to get AIS
on your yacht

AIS is a collision avoidance system.

As from December 2004, the International Maritime Organization (IMO) requires all ships over 300GT and passenger vessels of any size to carry an AIS VHF transponder on board.
Ships equipped with AIS will continually transmit their position, course, speed and other relevant data via dedicated VHF frequencies.
Other AIS equipped ships will receive the vessels information and will be able to identify and track it on electronic navigation charts.
. The information is transmitted on channels 87 and 88 and can be received within approximately a 20 to 30 NM radius or an area of 400 to 900 sq NM.
All vessels worldwide receive similar information from AIS equipped ships, within their VHF area.
The higher the antenna the further the range and is virtually only restricted by the curvature of the earth and propagation.
Putting your antenna on a 700 m. high mountain will give you a range of 200NM.
There is long range (tracking via satellite) and short range AIS (via VHF); seeing we are looking at anti collision, this item discusses VHF based systems only.
The introduction of AIS was a large step towards improved navigational safety worldwide, with significant benefits to crews and ship owners alike.
AIS will virtually eliminate the need for VHF traffic communication, uncertainty of other ships actions and prevent degrading of information, like radar, when in adverse weather conditions.
Modern day pirates intercepting ships of the coast of Somalia utilize AIS.
If the pirates can track ships to intercept, yachties can track ships also, in order to avoid them.
A commercial ships speed is 15 to 35 Knots; upon seeing a yacht ahead of them, they cannot just stop or change course.
The officer on watch, most probably does not see even the yacht at all, as their vertical angle of observation is pretty small, especially on container ships.
In other words don't count on them to get out of the way, it s the smaller boat that will have to move to avoid a collision.
Picture the following scene, which has happened to many yachties before:
You are sailing in the tropics. 5 Knots of warm breeze on the beam. Main and mps are doing their best to catch whatever wind there is. The boat is cruising at 3 knots. The autopilot is doing its job and you haven't seen another boat for days.
Than you notice something different in the corner of your eye, turning your head, you look at the horizon; get the binoculars. -----So we are not alone on this earth.
By the time you figured out that you are on a collision course, you have around 3 minutes left to move out of harms way.
A high spec radar would have given you 7 minutes notice at best.

If on the other hand, you had AIS, you would have had at least an hour or two notice.

The installation of an AIS transponder on non-SOLAS vessels (e.g. small leisure or fishing vessels, less than 300 GT) is optional and you are allowed only to use a CLASS B transponder.
Class B transponders are cheaper than Class A. The price of a 'Class B' transponder varies from US$1500 to $2500.
These prices are al good and well, but for the average yachtie rather high.
There is a much cheaper solution.

The object is of the exercise is collision avoidance and seeing that small ships move out of the way first, it would be prudent just to have AIS reception on a yacht.
If you own a VHF, GPS and a laptop, you already have 98% of the hardware needed for AIS.
The remaining 2% consist of software and a slight modification of your VHF radio.
In order to distinguish AIS data, your VHF needs to have an additional audio filter and a chassis socket installed for output to your laptop.
Of course you can still operate your VHF just the same, as before the filter installation.

What you get:

Installation of the AIS data filter and chassis socket into your VHF.
Standard connection cable 1.5m long. (3 and 5m long available also)
Plotting software
Installation manual
All the 2008 Pacific charts listed in the NZ Chart Catalogue 14th edition June 2009 and charts for the US, Australia and the Pacific.
Lots more software utilities, useful for yachties on DVD.
A DIY package is also available, where it is impractical to mail the radio to Tauranga NZ