Wednesday, April 10, 2019

Starpath News — April 2019

• Tracking Jacob Adoram 
We are in contact with  former Starpath Student Jacob Adoram as he rows from Seattle to Cairns AU. He left on July 7 and now, after some 6,000 miles of rowing, he is just over 1,000 miles from Cairns. To make this event into a marine weather study project we have created a series of Google Earth overlays so you can see live conditions of wind, current, pressure, and sea state. We have an ongoing series of short articles introducing short video discussions of his progress. Start at the first post to get an overview of what we are doing, and check the index of overlays.  Even disregarding the factor there is a row boat somewhere around where we are covering, it is very interesting to see the ASCAT live satellite wind measurements.  For a jumpstart, if you have Google Earth installed you can click here to load the KML file

Our original goal was to try to get live measurements of ocean currents to compare with the RTOFS and the OSCAR predictions. This has not produced much fruit. First these two models do not often agree (they are totally different kinds of products) and second it is difficult for such a large boat with so little control to measure accurate boat speed and compass heading to compare with COG and SOG from GPS. The difference between these two vectors is the current we want to measure. In cases where both models did agree there was notable current (ie > 1 kt) and more or less aligned with the wind, then we do indeed see him make more progress than he would without the current, but that is about it.

On the other hand, we have had much more success in testing new simulated radar reflectivity forecasts of the FV3 GFS model. We discuss this new breakthrough in marine weather technology in Modern Marine Weather  (see pages 112 to 115), but now we see it live. Namely we can forecast to the hour when he should be in squalls and how severe they are using a GRIB format of the combined reflectivity,  and then compare that to his observations. These are easy to measure events so the data are good. We have just started this study but it does look promising in the cases we have had.  We use the program LuckGrib to download the FV3GFS data and display the reflectivity

• New Regiment of the Pole
In keeping with one of our unpunished mottos "Always old; always new," we have revamped the late 16th century celestial navigation tool called a Regiment of the Pole. This will be written up in  more detail shortly in our Navigation Blog. It is a way to read from the orientation of stars near the pole the correction to a Polaris sight needed to find latitude.  We had originally developed a prescription for this in the mid 80s for the book Emergency Navigation, and now we are fine tuning that one. It is the same general principle, but with a relatively easy addition we get more accurate results.  This new method is used in our new book GPS Backup with a Mark 3 Sextant.  With this rule and a sextant, you can find your latitude in the Northern Hemisphere to within a few miles on any date without any further tables.

• Weather Trainer Live Updates
Over the past few months we have updated Weather Trainer in several ways. We have updated the content and reorganized several of the sections.  We also now have the Mac and PC versions working in the same manner, and we have changed the general structure of this cloud based service and training tool. The initial activation period remains at one year, but at the end of one year the subscription does not end if users have an active starpath web card of any kind, which includes being registered in any course. If you sign up for a second course after the weather course, for example, then the Weather Trainer is active for another year at no charge. After your web card expires, you could come back in a year or two and reactivate a web card for as low as $17 and have full access to the Weather Trainer to check out all the latest resources.

• Looking into live online lectures
We have done a few short test runs on offering live online lectures. This looks promising and we will be pursuing that shortly. We will announce the courses in the Discussion Forums and in our Facebook page.

 You could call it experimentation… or you could call it tinkering.
We have experimenting with use of pitot tubes for anemometers. The idea came from a new product from Ireland that apparently works well at least for stronger winds.  It is nicely called the Wind Urchin.  This is too big for the mast head, but I do not see why it could not be made much smaller and then we read honest 3d wind direction and correct vector speed.  We now have a real pitot tube and a differential barometer for testing. All seems to work very simply, but to get accurate values at low wind speed will be challenging. The first application of this type we know about is in an observatory on Mt. Washington.

We are also experimenting with a new style of artificial horizon suitable for use with stars. It has a lot of promise but needs some work. Seems it is best tested during daylight with a low daytime moon so testing times are limited. As spring approaches we also gain the number one factor for good cel nav studies of any kind, namely warm weather!

1 comment:

Captdave said...

I think the live lectures are a great idea. I suggest sending an email to announce them, as one may not be on a forum for a few days and miss the announcement and Facebook is the last think I want to depend on to keep me up to date. Thanks.