21 June 2019

SSCA Weather Talk

Topic: Preparing your boat for blue water sailing

  • My definition of blue water sailing: sailing beyond the bounds of the departure weather forecast
  • Bluewater sailing requires you to be able to get updated weather forecasts while at sea, away from easy internet access
  • Which data? Will vary. For the East Coast of the US, for example:
    • Charts
      • Current surface Analysis
      • 24, 48, & 72 hr Forecasts
    • NWS Offshore Waters Text Forecast, including 'Discussion'
      • West-central North Atlantic FZNT22
      • New England FZNT21
    • Chris Parker’s  FL/Bahamas and US E Coast & W Atlantic Emails
    • GRIB Data for at least:
      • Wind strength and direction
      • Pressure
      • Wave height
      • Wave direction
      • 500 mb
      • Gulf Stream location and speed
    • Voice broadcasts
      • NWS
      • Chris Parker
      • Redundant if you have above.
    • Local barometric pressure (onboard barometer)
  • How to get it?
    • Key Tips:
      • Subscribe to as much data as possible
        • SailDocs - charts, text forecasts, most GRIB data
        • Chris Parker emails
        • Use LuckGrib app - updates by email for models not covered by Saildocs
      • User StarPath Marine Barometer app on phone and calibrate before departure
    • SSB
      • Capture radio faxes directly with computer or tablet app
      • Get Text and GRIB data by email (WinLink, SailMail)
    • Satellite (sat phone, Iridium Go, etc.)
      • All by email
      • Starpath Marine Barometer app
  • How to interpret it?
    • David Burch Modern Marine Weather"
    • Chris Parker « Coastal & Offshore Weather « 
  • Comparing SSB vs Sat Phone
    • Three costs:
      • In dollars (equipment and on-going costs)
      • In electricity
      • In human energy
    • SSB 
      • Dollars: higher in equipment cost, essentially free thereafter
      • Significant drain on the battery when fetching email (on our boat - not a problem if you have lots of electricity)
      • Significant drain on human energy  it takes real work to get the data!
    • Sat Phone 
      • Dollars: lower equipment cost, pricy ongoing costs 
      • Negligible battery drain
      • Negligiblehuman energy drain
  • My experience
    • SSB 
      • Radio fax charts fairly easy to get, but lower quality than email
      • GRIB data and text forecasts by email
      • Battery drain was serious on our boat, may not be an issue if you have lots of power available
      • Frustrating and tiring to use - perhaps because I tried to use SailMail on a Mac. Might be better on Windows laptop
    • Iridium Go
      • Easy to use
      • Reliable once I found the right location for the antenna
      • We have mainly data plan, so have plenty of data for the year
    • Bottom line: Iridium started out as ‘backup’ to SSB, but the roles soon swapped. The last trip, we used Iridium exclusively.
Try It Yourself

Send the following in a plain text email to query@saildocs.com:

sub http://tgftp.nws.noaa.gov/fax/QDTM85.TIF time=06:00 days=2
sub http://tgftp.nws.noaa.gov/fax/PYAA02.TIF time=06:00 days=2
sub http://tgftp.nws.noaa.gov/fax/PPAE00.TIF time=06:00 days=2
sub http://tgftp.nws.noaa.gov/fax/PWAM99.TIF time=06:00 days=2
sub FZNT21.KWBC time=06:00 days=2
sub FZNT22.KWBC time=06:00 days=2
sub gfs:25N,44N,70W,80W|0.5,0.5|0,6,...,36,48,...,96|Wind,PRESS,WAVES time=06:00 days=2

Doing so will subscribe you to weather charts, text forecasts, and GRIB data for 2 days. For an actual offshore passage, you could extend the subscription for duration of the passage.

For Gulf Stream data, send the following in a plain text email to request@offshore.luckgrib.com

grib: 1200fwnizI5ryxy8395LO9pinXXSRuSjmISjv4pYqnPSPpbn4RSPMgg4Ivp

Next Up:  What to do about fog?

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