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» Online Classroom   »   » Public Discussion of Inland and Coastal Navigation   » About Buoys and Electronic Tide Tables

   
Author Topic: About Buoys and Electronic Tide Tables
cmoller


 - posted June 23, 2014 11:07 AM      Profile for cmoller           Edit/Delete Post 
David,

I have just returned from 10 days sailing on a 54 foot sailboat. We were cruising the area from Block Island, Rhode Island to the tip of Cape Cod, MA. I was able to use my new skills and got some great results with sun-lines. To get more practice with my sextant I took multiple readings of Hs (sun) and then plotted the readings vs time to see how closely the points fell on a line. I was not able to observe any stars as every evening was overcast. All in I am very pleased with what I have learned from your course and I intend to go out again perhaps this fall so I can practice and hopefully get some star/planet fixes.

I discovered that I do not really understand buoy systems and how they are used. Our Captain told me that Nantucket Sound is one of the most complicated piloting situations anywhere. I am therefore anxious to take the Starpath Piloting course, but I wanted to ask if there is extensive instruction regarding the use of buoy systems. For example, we entered ocean straits where there are multiple channels and reading the buoys was difficult as sometimes there was a question as to whether we were returning to or arriving from sea. I am also confused about tidal currents as I was told by Coastal Explorer that current velocities are reported for different depths. This came up when I emailed them about the fact that we experienced a 4 knot current in Woods Hole at a time when the database from CE said it would be 1.2 kts max!I sent them a picture of the Number 5 buoy bent over to nearly horizontal as the water boiled by!

All the best,

Chris Moller

David Burch


 - posted June 23, 2014 11:45 AM      Profile for David Burch           Edit/Delete Post 
Glad to hear you had a good trip.

We cover all the buoy systems, but more to the point we cover how to navigate more generally, which means we are not really dependent on any particular buoy system. The meaning of buoys are almost always discernible from the chart, and it is not at all uncommon in many waters to have to look at a chart to see what a buoy means or intends. It can indeed be dangerous to do otherwise, especially with buoys of two colors.

We will also look into this current prediction issue, as it is fundamental to safe, versatile navigation. Do you have the time, date and location of the buoy picture, and maybe you could post it here.

The depths of the current reports are given in the current tables, at least in those waters, but i am not sure if echart programs ever take that into account. On the other hand, this is the wrong direction... i.e. suppose a program used the deep currents instead of surface by mistake. that would most often lead to stronger predictions, not weaker ones. Also very important for that region is the effect of lunar phase and location i.e. perigee or apogee, and currents also depend on the wind speed.

if you post the actual data we will have a more detailed look. It will be good training example.

thanks

From: Starpath, Seattle, WA


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