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AIS

McC272@aol.com

Thu, May 12, 2005 3:01 AM

There has been some discussion on the list about the value of full blown AIS
(i.e. transmit and receive compared to receive only). As the prices come
down and more and more people begin to think about full AIS, it raises the
question of how many targets there will be at one time in busier waters. Also, I
believe that on the commercial sets, there is the ability to eliminate
targets below some user settable threshold size. Someone with more knowledge than
I have can confirm this but I recall reading about some AIS testing on the
Inside Passage. If memory serves me, some of the bridge personnel on cruise
ships using it had a problem with seeing more AIS targets than they wanted to
see and they filtered out targets below a certain size, 65 feet as I recall.
They were most concerned with maneuvers in relation to their own kind! I
would expect that if the full blown sets have that capability, the big guys
would filter us little guys out. They expect us to get out of the way and I for
one engage in very defensive driving around them. The problem with such
filtering, if it occurs, is that the units will be set once and not adjusted so
the filter will remain set for busy waters even when the ship is in mid
ocean. In short, just because you are transmitting your AIS information does not
mean that everyone with an AIS unit will be listening. Just something to
think about.

Jim

(Jim & Mim McCrea, mcc272@aol.com Nordic Tug 37-134 "North Star" Home Port
Norwalk, CT)

There has been some discussion on the list about the value of full blown AIS (i.e. transmit and receive compared to receive only). As the prices come down and more and more people begin to think about full AIS, it raises the question of how many targets there will be at one time in busier waters. Also, I believe that on the commercial sets, there is the ability to eliminate targets below some user settable threshold size. Someone with more knowledge than I have can confirm this but I recall reading about some AIS testing on the Inside Passage. If memory serves me, some of the bridge personnel on cruise ships using it had a problem with seeing more AIS targets than they wanted to see and they filtered out targets below a certain size, 65 feet as I recall. They were most concerned with maneuvers in relation to their own kind! I would expect that if the full blown sets have that capability, the big guys would filter us little guys out. They expect us to get out of the way and I for one engage in very defensive driving around them. The problem with such filtering, if it occurs, is that the units will be set once and not adjusted so the filter will remain set for busy waters even when the ship is in mid ocean. In short, just because you are transmitting your AIS information does not mean that everyone with an AIS unit will be listening. Just something to think about. Jim (Jim & Mim McCrea, mcc272@aol.com Nordic Tug 37-134 "North Star" Home Port Norwalk, CT)

Andrew & Linda Fraser

Thu, May 12, 2005 4:09 AM

Andrew Fraser
M/V KAISOOBA N46

Jim said . The problem with such
filtering, if it occurs, is that the units will be set once and not
adjusted so
the filter will remain set for busy waters even when the ship is in mid
ocean. In short, just because you are transmitting your AIS information
does not
mean that everyone with an AIS unit will be listening. Just something to
think about.

Jim

(Jim & Mim McCrea, mcc272@aol.com Nordic Tug 37-134 "North Star" Home Port
Norwalk, CT)
ssagemaking-Under-Power Mailing List

Jim is so right in what he says. The way I look at it is that the more chances I have of being seen the better. If it is by the big guys and or the little guys it sure can't hurt. As long you go with the idea that they do not see you and you just stay out of the way as we do now you should be ok. Andrew Fraser M/V KAISOOBA N46 Jim said . The problem with such filtering, if it occurs, is that the units will be set once and not adjusted so the filter will remain set for busy waters even when the ship is in mid ocean. In short, just because you are transmitting your AIS information does not mean that everyone with an AIS unit will be listening. Just something to think about. Jim (Jim & Mim McCrea, mcc272@aol.com Nordic Tug 37-134 "North Star" Home Port Norwalk, CT) ssagemaking-Under-Power Mailing List