Hitting a weather buoy - what about radar?
Peter makes excellent points. I think that radar should be "worked" that is
going out to a 12 to 16 mile range every 15 or so minutes and running at 3 to
6 mile range inbetween the looks. You may have to adjust for each range--but
since you are repeating these, it is easy. That size bouy should have been
picked up 15 to 30 minutes before on the longer range. If the radar was not
working, that should have been noted when the watch changed. Standing a
watch, is just that standing a watch and looking around. Even with starlight,
you can see objects or feel a presense of somthing there. If it was very
rough, then possiably the bouy was lost in the sea clutter--but should not
have been if the watch stander was really watching the radar and adjusting
regularly to bring out objects of the clutter. Also the skipper should have
been aware that a mile is not enough room to give to these bouys. This should
have been discussed at change of watch.
Is it possiable that the light was stolen--maybe, but I suspect unlikely. The
bouys have solar charged AGM type of batteries, which are checked regularly.
The data transmission is also dependant on these batteries--if the battery had
failed, NOAA would know that . The lights are on a sequencer, when a light
fails, another bulb rotates into place.
I have friends who have hit bouys, other boats etc--in each case they were not
standing an adequate watch--and they admited it.
Bob Austin
"Bob Austin" thataway4@cox.net
At 12:56 PM 2/24/05 -0600, you wrote:
Peter makes excellent points. I think that radar should be "worked" that is
going out to a 12 to 16 mile range every 15 or so minutes and running at 3 to
6 mile range inbetween the looks. You may have to adjust for each range--but
Bob,
A few comments. I generally use a 3 mile range with the boat offset towards
the bottom of the screen, this gets me 4-5 miles of range up forward and
cuts down on what the radar sees behind the boat. In most cases I consider
this an acceptable tradeoff. I don't see the use of 12-16 miles except for
watching the coast as on most of the boats we run the radar is not high
enough or maybe powerful to detect even a big ship at that distance. If
the radar is setup in the mode I described above, then jumping to the 6
mile range will give a forward look of about 8-9 miles. For detecting small
or even large floating targets, these are practical limits. The assumptions
here are that the boat is about 50' or less, has a radar of 4 kw mounted no
more than 20' or so above water. Any of the common radars on our boats
generally have characteristics that make any range scale over 3 miles in
use, as not being optimal for detecting targets of other small vessels, or
for that matter buoys. The jump from 3 to 4 or 6 miles should generally not
require an adjustment and as I consider this adjustment sequence to be
major source of error, doing it repetitively is a hazard.
In summary there is little to be gained and much to be lost by using a
range over 3 miles, even while in the open, as the pulse length, repetition
rate and received signal of a 4 kw x band radar will not pick up the
targets that we are most interested in and most likely to miss visually.
The use of a long range scale unsuited to the targets to be detected is the
single biggest mistake in the use of radar by small boat operators. I am
not arguing that no changes of scale should be employed, only that I think
the technique is overused.
Regards,
Mike
Capt. Mike Maurice
Tualatin(Portland), Oregon
--- Bob Austin thataway4@cox.net wrote:
I think that radar
should be "worked" that is going out to a 12 to 16
mile range every 15 or so minutes and running at 3
to 6 mile range inbetween the looks. You may have
to adjust for each range--but since you are
repeating these, it is easy. That size bouy should
have been picked up 15 to 30 minutes before on the
longer range.
With the input of Kevin Monahan, author of The Radar
Book (Fine Edge Publishing), I put together a 1-page
sheet on adjusting radar and posted it to my website.
http://www.seaskills.com/Download.html (left column,
third down)
The incident described involved seasoned offshore
people, so I have to believe (as someone already
suggested), we are all vulnerable to making a similar
mistake - vigilance and luck notwithstanding.
Incidences like this are very easy to dissect in
retrospect, but not obvious as they unfold.
However, if there was a single take-away from the
article (it was a first-person account by the owner -
the weather was a non-issue), its the importance of
correlating all data sources: if theres something
thats supposed to be in the area (chart plotter, dead
reckoning), hunt/track it down visually and with
radar, and dont give up until you are satisfied in
this case, the light on the weather buoy was
malfunctioning (tell the Coast Guard if there isnt
already a Notice to Mariners, there will be). Since
this involved a sailboat, its possible the radar was
below decks explaining why the helmsman relied on
visual identification.
Kevin Monahan, author of The Radar Book, puts it very
eloquently: Theres no way to walk up to radar and
tell if its adjusted properly. If there is a single
biggest oversight in using radar, its that many
people set it and forget it. As Bob Austin noted, it
takes frequent ranging in/out and adjustment of the
controls. Most people seem to run on 4-6 mile range as
the default. But very few people I have observed
maximize their radars, and fewer practice these skills
at all (how hard can it be?).
Sources for learning more include:
www.TrawlerFest.com (most of the TFs will have a 90
minute seminar presented by either Kevin or myself)
http://www.fineedge.com (they are hosting several
weekend seminars around the country, radar by Kevin
Monahan is a portion of this series)
Pacific Sail Expo (tentative), Oakland CA, April 2005.
A 90 minute Radar seminar will be presented by myself,
free after admission to the show
www.starpath.com - simulation software
Peter
www.seaskills.com
Peter,
I'm blessed with a 1985 Furuno 805D, 12" radar which constantly changes
ranges by itself! So, I'm constantly trying to clean the rotary contact
switch by changing ranges myself.
Seriously, this makes me choose and tune ranges more frequently than
otherwise. She can reach 48miles, but 6 and 3 miles are good for my
navigation. This open wave-guide antenna is better at picking out buoys and
moving targets than my eyes. Sometimes though, it is only a clue to where to
look with my binoculars. I look forward to cleaning it up and inputing 0183
GPS data to it.
Still, sea clutter is a sensitive adjustment and I still don't try to use
alarms. I'd be unsure of spotting a NOAA buoy unless it had a radar
reflector.
Believe it or not, there are corallaries to this on the ICW. There are
numerous uncharted/new "daymarks" in North Carolina which the radar reveals
and I follow-up with binoculars or spotlight. Not sure what would happen if
they hadn't appeared on radar. Small surprise in daylight and big surprise
at night.
Ron Rogers
46042, outside the middle of Monterey Bay, CA, presents a fairly good radar
return. It is frequently on the way to the tuna grounds in season so
everyone here is pretty used to looking out for it. It is near the trench so
the watch circle is quite large and I am frequently surprised at how far
from my last 'waypoint' setting I find it floating. I have reviewed all of
the NOAA buoys and they all should produce a good blip. 46042 isn't that big
but I sure wouldn't want to run into it... looks pretty sturdy.
That Cape Hatt buoy was the one clocking 50 foot seas during a blow a few
years back. So much nicer 'watching' from the internet than actually being
there. It went off-line the next hour.
Jim