On Apr 3, 8:26 am, "Roger Long" wrote:
I want to expand on something I hinted at in a reply to Skip's preventative
measures post.

You know how the position circle on a GPS gets larger and smaller depending
on the sattelite coverage? You keep the circle off the bad spots, not the
center of the circle because you could be anywhere within it.

There should be another, mental, circle around the GPS location or the
pencil fix on your chart and it should be projected forwards along the
track. This circle gets larger and smaller depending upon many factors. This
circle should be kept clear of anything hard or areas of breaking water.

Some factors that make the circle bigger (No priority implied):

Falling tide

Swell

Hard bottom

Fatigue

Imminent bad weather

Poor visual back up for GPS

Poor quality chart coverage

Possible equipment problems

Sail settings that may hinder maneuverability

Poor visibility

Etc., etc.

Factors that make the circle smaller:

Local knowledge

Good visibility and weather conditions

Rising tide

Soft bottom

Etc, etc.

Running these factors through your mind, at least in the background, is
valuable not only for establishing the size of your buffer but for
increasing overall situation awareness.

From Skip's account, I see their real error as treating their navigation
position as a point and letting the circle get too small. Based on
assurances from others that the entrance was doable, they pressed on. It was
doable, with good weather and either local knowledge or fresh and alert when
the navigation circle might be 100 yards. Their navigation circle at the
time should have been about ten miles in diameter.

The instructions to the watch stander in a situation like that shouldn't be,
"Wake me if we get close to something or you think you need me." It should
be, "Wake be when we are within ten miles of ____"

In conditions like that I wouldn't count on being woken up. The watch
stander could fall asleep or zone out. Figure out the shortest time that the
edge of your navigation circle could touch anything bad with a worst case
calculation of speed and course. Set a loud alarm for that time. You might
also be able to do it with various alarm settings. Best to do all three in
challenging conditions. You'll sleep better.

--
Roger Long

Well said Roger, I use a very loud wind up alarm clock next to the
pillow. I sleep in the wheel house.
I'd add that a nice radar range alarm helps to.
After a day or two it's easy to wake in different wave
patterns(course, speeds, weather)
Plotting a course on a paper chart and having part of the watch
requirements being fixing your GPS position along that chart every 30
min helps. It gives the wheel watch something to do to help stave of
sleep, and if done correctly (which is the most basic navigation skill
needed to venture offshore) will prevent you from grounding, or ending
up way off course.

As far a sleeping on the wheel watch goes, that's a capitol offence.
Anyone on any boat I've ever ran found sleeping on watch was sent
below to pack his bag. No call for it. Thats rule number one, as you
stated no crew member would ever be punished or looked down upon if
they wake the skipper and say they are to tired to safely man the
helm.

Joe