Weather info when offshore

[Ostara24]

Predictwind has a lot going for it, access on wifi costal or through iridium Go /Stalink offshore, never failed me and allows numerous models to be downloaded and compared. Its a no brainer for me and has been for 12 years now.

Luck grib is also very good as above, on or offshore, again very stable and reliable.

 

[franksingleton]

Predictwind has a lot going for it, access on wifi costal or through iridium Go /Stalink offshore, never failed me and allows numerous models to be downloaded and compared. Its a no brainer for me and has been for 12 years now.

Luck grib is also very good as above, on or offshore, again very stable and reliable.

As long as you ignore PWG and PWE, no problems with PW as long as you ignore their advertising hype. The experts in wind forecasting are ECMWF, NOAA, Met Office etc. PW are experts in presentation and delivery. Don’t get hooked on intermodal comparison. 4 or 5 models is too small an ensemble. If all are showing similar outcomes, it is encouraging. No more. If one model is an outlier, that may, in fact, be the best on the day. If there is an outlier, treat all with caution.Take a look at Meteociel tabulated output of winds from one model.

 

[GHA]

As long as you ignore PWG and PWE, no problems with PW as long as you ignore their advertising hype. The experts in wind forecasting are ECMWF, NOAA, Met Office etc. PW are experts in presentation and delivery. Don’t get hooked on intermodal comparison. 4 or 5 models is too small an ensemble. If all are showing similar outcomes, it is encouraging. No more. If one model is an outlier, that may, in fact, be the best on the day. If there is an outlier, treat all with caution.Take a look at Meteociel tabulated output of winds from one model.

I keep coming back to "is having any weather forecasts actually of any use way out in the ocean?".
Not so sure, west to east N atlantic probably, to get slightly better positioned as the lows go through.
And for landfall could be handy a few days out so you could heave to well off if there was some bad stuff coming through. But other than that... not sure it actually makes too much difference either way if you know what the winds will do, not a huge amount you can do.
Anyway, excited by recent success getting gribs over ham radio, next passage think I'll log actual against forecast somehow, nice to have some kind of structure to the day
Last passage from Madeira>Algarve, couple of random times ¨boat wind >>



and noon pretty close 9Kts forecast >


18:00 not bad either, 13Kts forecast >>



So close enough, I thought the actual seemed a bit higher out there but maybe not.

Is there any kind of data standard presentation for comparing actual against forecast in meteorological circles?

 

[geem]

I keep coming back to "is having any weather forecasts actually of any use way out in the ocean?".
Not so sure, west to east N atlantic probably, to get slightly better positioned as the lows go through.
And for landfall could be handy a few days out so you could heave to well off if there was some bad stuff coming through. But other than that... not sure it actually makes too much difference either way if you know what the winds will do, not a huge amount you can do.
Anyway, excited by recent success getting gribs over ham radio, next passage think I'll log actual against forecast somehow, nice to have some kind of structure to the day
Last passage from Madeira>Algarve, couple of random times ¨boat wind >>
View attachment 178323


and noon pretty close 9Kts forecast >
View attachment 178324

18:00 not bad either, 13Kts forecast >>
View attachment 178325


So close enough, I thought the actual seemed a bit higher out there but maybe not.

Is there any kind of data standard presentation for comparing actual against forecast in meteorological circles?

If you have a very slow boat, then maybe it won't make much difference. If you are fast enough to constantly position yourself in favourable weather as we were on our recent west to east crossing then good weather information makes a huge difference. We were able to ride narrow bands of wind when calms existed all around us and hang onto a low pressure system and ride favourable SW winds. This all contributed to great sailing conditions and a fast and enjoyable passage.

 

[GHA]

If you have a very slow boat, then maybe it won't make much difference. If you are fast enough to constantly position yourself in favourable weather as we were on our recent west to east crossing then good weather information makes a huge difference. We were able to ride narrow bands of wind when calms existed all around us and hang onto a low pressure system and ride favourable SW winds. This all contributed to great sailing conditions and a fast and enjoyable passage.

thing is we're all absolutely riddled with conformation bias, & it's extremely difficult to actually quantify if it is a big difference or just seeing what we want to see...
offshore the forcasts aren't as good anyway with much less data to go on, could be the real world wasn't as precise as the forecasts, noticed that a lot on my last couple passages even with recent gribs. & ascat is too broad a brush to be much use locally.
Maybe......... maybe not, we don't actually know that much for sure..

 

[geem]

thing is we're all absolutely riddled with conformation bias, & it's extremely difficult to actually quantify if it is a big difference or just seeing what we want to see...
offshore the forcasts aren't as good anyway with much less data to go on, could be the real world wasn't as precise as the forecasts, noticed that a lot on my last couple passages even with recent gribs. & ascat is too broad a brush to be much use locally.
Maybe......... maybe not, we don't actually know that much for sure..

We we had excellent weather routing using the ECMWF model mainly, with GFS as a confirmation. We got the conditions that the model was telling us, repeatedly. By giving our weather routing friend, our position and weather conditions, he was able to assess our position relative to the changes in the weather. With this information, he was able to give us great advice. Other boats that should have had similar performance to us, with poor weather advice took far longer. They motored far more than us even though they left at the same time. Like I say, if your boat is fast enough to take advantage of good weather information then it makes a world of difference in my experience

 

[GHA]

We we had excellent weather routing using the ECMWF model mainly, with GFS as a confirmation. We got the conditions that the model was telling us, repeatedly. By giving our weather routing friend, our position and weather conditions, he was able to assess our position relative to the changes in the weather. With this information, he was able to give us great advice. Other boats that should have had similar performance to us, with poor weather advice took far longer. They motored far more than us even though they left at the same time. Like I say, if your boat is fast enough to take advantage of good weather information then it makes a world of difference in my experience

Over the years I've got into the habit of not being so sure about anything at all on a boat, being riddled with conformation bias like everyone else ....

 

[GHA]

sdrifting a bit, the next opencpn grib plugin looks useful, just installed the new beta 5.9 opencpn

 

[franksingleton]

If you have a very slow boat, then maybe it won't make much difference. If you are fast enough to constantly position yourself in favourable weather as we were on our recent west to east crossing then good weather information makes a huge difference. We were able to ride narrow bands of wind when calms existed all around us and hang onto a low pressure system and ride favourable SW winds. This all contributed to great sailing conditions and a fast and enjoyable passage.

A RTW winning navigator once told me that in his slow 40 footer, on an ocean passage, he chose a good slot to get clear of land and then took whatever came. Obviously, he chose time of year carefully. On the RTW, he updated 6 hourly to minimise time to be on course to next waypoint in 10 days’ time.

 

[geem]

A RTW winning navigator once told me that in his slow 40 footer, on an ocean passage, he chose a good slot to get clear of land and then took whatever came. Obviously, he chose time of year carefully. On the RTW, he updated 6 hourly to minimise time to be on course to next waypoint in 10 days’ time.

Yep, you can only choose the weather you leave on.
Edit:
Unless you are on the ARC cos they just leave on a set date so you don't get to choose anything

 

[franksingleton]

Yep, you can only choose the weather you leave on.
Edit:
Unless you are on the ARC cos they just leave on a set date so you don't get to choose anything

The timing of a Christmas meal never deems to me to be a good passage planning tool

 

[Sandy]

The timing of a Christmas meal never deems to me to be a good passage planning tool

1400 hrs UTC is the usual time in this household.