"Bobsprit" wrote in message
| How does this "amplify" the importance when we were, for all intents and
| purposes sailing a short line of sight course? We estimated our losses at
| aprox. 90 minutes and were quite close. For a 55 mile run I don't see the
need
| for more than crude navigation. We know the waters.

Must be the description of your trip that confused me...

You wrote:
"Observing the track set on the GPS, sailing on a reach, with 1.5-2.5
knots of
current against, we only deviated from our track by about a mile."

So you were on a single tack for this portion of the return trip? If you
completed several tacks ... how would you calculate the combined drift or
set for cross track error.. the changing conditions would not allow a
cumulative average unless you did the calcs on paper to derive it. Hence my
statement regarding a hard plot.

This description led me to believe that prior to the 20 mile leg you did not
have line of sight. My apologies... but it seems to read that way.

"Once 20 miles of the return trip were under the keel we could see the
Manhattan skyline and
it became a line-of-site sail, though i maintained a specific (245 If I
remember right) SW compass heading anyway."

| Next Spring when we do Great Gull and Block, we'll employ a higher level
to
| navigate safely.
| In one respect, you're correct; the practice is probably worth the effort.
| Maybe when we sail to Norwalk (a very short sail) we'll plot a series of
| waypoints, calculate current and play by the book for the practice.

I look forward to your report and the discussion it will surely generate.

CM

This description led me to believe that prior to the 20 mile leg you did not
have line of sight. My apologies... but it seems to read that way.

We did not, nor did we face the worst of the current in the first few hours,
making our course fairly "true" especially in respect to the distance involved.
By maintaining our compass heading derived from the GPS, we barely deviated at
all.

RB

"Bobsprit" wrote in message
...
| This description led me to believe that prior to the 20 mile leg you did
not
| have line of sight. My apologies... but it seems to read that way.
|
| We did not, nor did we face the worst of the current in the first few
hours,
| making our course fairly "true" especially in respect to the distance
involved.
| By maintaining our compass heading derived from the GPS, we barely
deviated at
| all.

Ah.. I see how I came to be confused since you wrote... "How does this
"amplify" the importance when we were, for all intents andpurposes sailing a
short line of sight course? "
Cross track.. or drift and set are easier to estimate on a single tack and
more readily confirmed by bearing bearing fix or in the case of limited
bearing targets.. running fixes.

How did the Compass vs. GPS bearings compare? Did the discrepancy amount to
the Variation and did you get a chance to confirm if the Deviation error
made much of a difference?

Isn't this stuff interesting.... ;-)

CM

| waypoints, calculate current and play by the book for the practice.

I look forward to your report and the discussion it will surely generate.

Indeed!

RB