PredictWind? Weatherfax? What weather system do you recommend for crossing oceans?

[Snore]

I can only add one thing to the great information in this thread. And that is don't dismiss guys like Chris Parker.

Prudent navigators use multiple sources of info. Likewise prudent mariners will have more than one source of info. Having a relationship with Chris gives me someone 'off the boat' who can do more than read the weather. Be it a delivery or a long cruising passage, things can get challenging for the master. Having someone off the boat, whose sole job is weather, versus doing weather when tired is just prudent.

To add another variable, anyone else using the 500mb charts?

[conachair]

Originally Posted by Snore

To add another variable, anyone else using the 500mb charts?

Most days have look at the gfs spag 5460 though mainly as a really quick glance at what's likely in the next week or so, if the different runs agree and it's pointing at Norway then very likely it warm and sunny in the algarve. Which it usually is anyway . Once they hinted at a cut off low forming off Morocco which didn't show up in the synoptic or gribs for a day or so, which might have been useful to get ready if you wanted some rare south wind to get up the Portuguese Atlantic coast.

[Discovery 15797]

LONG POST FOLLOWS....(get a cup of coffee)....

Originally Posted by magentawave

1) How accurate are PredictWinds Departure Planning and Weather Routing features using Iridium Go in the middle of the Pacific?

2) To get PredictWinds Departure Planning and Weather Routing features you have to buy their Standard package at $250 per year or Professional package at $500 per year.

There is some great advice in this thread. I will give you my advice from my latest experience with the Iridium Go and PredictWind and marine SSB/Ham radio sailing from Seattle to Honolulu in August 2019.

Iridium Go and PredictWind features are accurate in the middle of the Pacific. The weather routing feature put me on a rhumb line course rather than the traditional course. PredictWind will always give you the most direct course to destination and route you via details you specify on their website (e.g. polars, comfort adjustments, etc.) The more accurate you can define the polar speed adjustments for your vessel, the more accurate your routing will be.

It's like any software...the more features you know how to use correctly, the better the software will behave for you.

IMHO...you do not need the professional package. Predominant ocean currents are very predictable, Current charts based on tidal flows for various inland and coastal locales around the world are widely available and highly accurate.

Also, IMHO...with the ability to download weather maps daily and the knowledge to interpret them, means the days of professional weather router's may be limited (mostly for novices or lazy people with deep pockets) in the future. I never once felt the need for advice from a professional weather routing service basically looking at the same info I had (which is sometimes not the same as reality at the moment or ability to look out at the horizon in front of you). I'm not claiming to be a professional weather forecaster and I'm sure they have talents far beyond my novice skill, but given the right tools and training weather routing and course planning is not rocket science...it's more of a SWAG.

Some additional notes...

The external antenna does make a difference SOMETIMES. I mounted my Iridium go inside my pilothouse at the nav station. I experimented with the external antenna connected and disconnected at various points along the route. There were times it did not make a difference, and there were times (middle of Pacific) it did make a difference in reception. If you keep your transceiver in your cockpit...maybe not...I personally like it mounted in the security of the nav station.

Text messaging and email - The Iridium Go setup also provides text messaging and email capabilities. I got the unlimited data package with 150 talk minutes.

Tracking & "blog" - PredictWind provides a tracking website so friends and family can see your progress. (ex. Discovery15797). Prior to leaving, with tongue in cheek, I had told friends and family if they saw me heading northward it was to avoid a storm...if they saw me heading east it was because something went wrong. Indeed, my brand new forestay gave way 850 miles off the coast and I had to turn around plot a course back to SF using PredictWind to ensure the wind was never less than 100 degrees on the bow.

There is some weird stuff with the Iridium package. You can setup up to 5 users, but every user can see all the text messages sent and received by other users. So, I don't really understand why you need to setup different users with different passwords other than email.

Also, the separate Email & Web app is crap. It's not intuitive. I also found that after downloading emails I would have to reset my iPad and the Iridium Go device before I could download GRIB files again. My routine was to download GRIBs once in the morning, sometimes in the evening, and email once each night.

You can download synoptic charts via SSB without a Pactor Modem. I also have an Icom M-802. I do not have a Pactor. I do have the Black Cat HF Weather Fax Marine Radio Fascimile Decoder for iPad (see https://www.sea-tech.com/2018/10/21/...one-or-tablet/) Personally, I found the information downloaded on Iridium much more informative than the synoptic charts downloaded via SSB. Since the Iridium package gave me both email and sms text capabilities there was no need for added expense of SailMail or Winlink.

I decided to go with Iridium rather than SCS Pactor for a couple reasons. First, although Iridium is slower than Pactor I do believe that satellite systems will get better in future as they become more prevalent. (Growing customer base will push for greater capabilities.) The cost of a Pactor modem is ridiculously high and doesn't give me anything I can't get for (essentially) free at reduced speed (longer download times).

Also, consider that you are only making about 120 - 140 nm per day. Looking at weather 5 days out is crazy and all weather models are based on "best guess." I downloaded GRIBs with wind, gust, pressure, and CAPE info for 3 days out every day...sometimes twice a day. This seemed to give me the most accurate info underway via the PredictWind Offshore app.

For departure planning I used the PredictWind website and an internet connection. (This is also where you need to setup your boat's polar speed adjustments). Again, I would say the better you understand the software...the more confident you will be in the info it provides you. I would allow at least 2 weeks time to practice with the software package prior to your planned departure date. Don't pay to activate the system the day before you depart.

If you have any other specific questions feel free to pm me.

[Discovery 15797]

Originally Posted by Marathon1150

2. An Icom 802 with Pactor Modem. We used this for Gribs including synoptic charts so we could see what was around us in terms of isobars rather than just the wind vectors that PW provides. This improved our ability to determine which PW model was likely to be the most accurate on any given day. Including for departure and route forecasts. We used this for SailMail as well from time to time but the IG is much better in terms of reliable connections.

PredictWind also provides Isobar information; it does not provide synoptic information on troughs and ridges.

It is also helpful to understand the difference between prognostic charts as compared to synoptic charts.

[DawnTreader]

We use the predictwind/iridium go despite being on a budget and the package being very expensive. We justify the cost because Predictwind has the euro model, essential for determining forecast confidence when comparing to the gfs, and it also shows tidal currents (and ocean currents). Without knowing what the water is doing, it is very difficult to identify potential hazard areas.

[jackdale]

I have used a variety set ups on the various boats on which I have made passages.

My favourite hi-tech set up:

Iridium Go
SailDocs for grib files, weatherfax images and Navtex
SailGrib WR on my Android tablet

My favourite lo-tech set-up:

barometer - with 24 hour history
my eyes - watching clouds, sea state, and wind speed and direction
all noted in the deck log

[jackdale]

Originally Posted by Snore

To add another variable, anyone else using the 500mb charts?

In the North Pacific, it is a must for tracking and forecasting high and low pressure systems.

You can download the image (and other weather fax) from SailDocs.

[DawnTreader]

I don't really find the 500mb charts very useful anymore, now that multiple model gribs are easily available. If all you had was an 24hr isobar chart, then the 500mb would be very helpful. They are a bit esoteric to read, so maybe I'm missing something.

[jackdale]

Originally Posted by DawnTreader

I don't really find the 500mb charts very useful anymore, now that multiple model gribs are easily available. If all you had was an 24hr isobar chart, then the 500mb would be very helpful. They are a bit esoteric to read, so maybe I'm missing something.

I sat in a presentation by Lee Chesneau on using the 500mb analysis. It was very instructive.

I like the fact that weatherfax has a human intervention, not the the output from a computer model.

[jackdale]

Originally Posted by jackdale

I sat in a presentation by Lee Chesneau on using the 500mb analysis. It was very instructive.

I like the fact that weatherfax has a human intervention, not the the output from a computer model.

Good classic article of the 500mb analysis

https://ocean.weather.gov/articles/m...00mb_chart.pdf

[DawnTreader]

I have many friends who took the meteorology class with Lee Chesneau. They all had good things to say about it. Unfortunately when I was taking my CM upgrade classes, I took Meteorolgy with someone else. Still, with the info available on predictwind, namely wind gusts, CAPE index, and currents in addition to the normal data (wind, waves, surface pressure, temp) and with both the GFS and Euro models, the weather fax charts lack a lot detail and accuracy. It is certainly fine, and if you could only have one snapshot of a weather chart, the 500mb would probably be the most telling, and weatherfax is free and there is a lot to be said about that. Unfortunately there is no good weather fax where we are currently sailing.

[conachair]

Originally Posted by jackdale

barometer - with 24 hour history

And add a few dollars chip to a raspberry pi and you'll be head and shoulders above everyone else!

Near miss from a small tornado

[Paul L]

Originally Posted by DawnTreader

I don't really find the 500mb charts very useful anymore, now that multiple model gribs are easily available. .....

I also don't find them very practically useful. I took a Chesneau weather course where he primarily focused on the 500mb charts. The info up at that altitude is the driving force for much of our sealevel weather. It is also the driving force for the Grib models and the forecast charts. It is unlikely that I will ever be more of an expert in interpreting 500mb charts in each new cruising ground that I enter than the models or forecasters already are. Using the Grib models with text forecast models works well for our passage weather planning.

[Exile]

Originally Posted by conachair

And add a few dollars chip to a raspberry pi and you'll be head and shoulders above everyone else!

Near miss from a small tornado

Interesting recording of a tornado! There are also some phone apps that perform as barographs, i.e. displaying historical readings. Assuming your device has a built-in barometer that is. The only catch (from what I've observed) is that the app must remain open on your device. I simply note readings from my old school barometer on the bulkhead every time I make a log entry.

[Auspicious]

Originally Posted by DawnTreader

I don't really find the 500mb charts very useful anymore, now that multiple model gribs are easily available. If all you had was an 24hr isobar chart, then the 500mb would be very helpful. They are a bit esoteric to read, so maybe I'm missing something.

Originally Posted by jackdale

I sat in a presentation by Lee Chesneau on using the 500mb analysis. It was very instructive.

I like the fact that weatherfax has a human intervention, not the the output from a computer model.

The 500 mb charts show the forces that steer sea level weather. For me they provide two benefits: QA on the surface forecasts and a heads up on what to expect at a macro level beyond the scope of current forecasts.



Synoptic charts over weather fax are a gift to cruisers. I simply don't understand why people use gribs when such better information is available.

Originally Posted by DawnTreader

Unfortunately there is no good weather fax where we are currently sailing.

Where are you? To my knowledge there is one place on the planet without good products.