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Where does Latitude 38 get their tide & Current data?


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Every month, Latitude 38 gives weekend tide & current info for the Golden Gate. August has Labor Day which is always on a Monday. Latitude doesn't have Monday's tides and currents. I am going up the San Joaquin River on Monday.

Tides are easy enough to get; currents, not so much. Since my boat is new to SF Bay, I don't have tide and current tables and everyone seems to be out.

So, where does Latitude get them. I have used them and trust them. Google search results, not so much.

Thanks!

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Get AyeTides app on your iPhone.  That's all you need for currents, worldwide. Easy to read and use.

Add Compass, BuoyData, FindShip, WindAlert, PredictWind and Navionics charts for the West Coast and you have a complete coastal navigation package.  Plus they all have regular updates.

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Tidetech is fantastic, especially for areas they have improved upon the free data (I.e SF Bay, The Solent etc.). It is also especially helpful if using Expedition or Adrena for navigation/route planning as this seems to be the only way to get even the free data into the Nav software in a read-able format.

Unfortunately, it’s pretty expensive for occasional use or cruising-only needs (roughly $480/yr at today’s exchange rate), especially if you are outside the areas they have modeled. For example, on the Chesapeake Bay, I can pull the same current model up for free on the NOAA website (https://tidesandcurrents.noaa.gov/ofs/ofs_mapplots.html?ofsregion=cb&subdomain=0&model_type=currents_forecast). Unfortunately I can’t easily pull that into Expedition, so one has to do a little math on their own when bay racing, or pay for the Tidetech subscription.

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You can pick up the yearly tidebook for free at Svensens or west marine. it does give you the tides and currents for each part of the bay. carry it on your boat as part of your sailing kit.

Screen Shot 2021-08-01 at 9.00.18 AM.png

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On 8/1/2021 at 8:40 AM, Black Jack said:

You can pick up the yearly tidebook for free at Svensens or west marine. it does give you the tides and currents for each part of the bay. carry it on your boat as part of your sailing kit.

Screen Shot 2021-08-01 at 9.00.18 AM.png

This ^^^ I pick up four . One for my pfd, one for the office, one at home and one in my truck. 

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Heck, go to the tide model and watch the tides and currents before you go!

https://www.spn.usace.army.mil/Missions/Recreation/Bay-Model-Visitor-Center/The-Bay-Model-Journey/

 

For what it's worth, we've pretty much started to ignore our iPad and laptop, and just go with an iPhone the navigator can stick in front of the driver's face for a quick glance.  All the apps I noted above are iPhone apps.  The cat's PJs for handy navigation, in my opinion.

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  • 4 weeks later...
On 8/1/2021 at 6:48 AM, F18 Sailor said:

Tidetech is fantastic, especially for areas they have improved upon the free data (I.e SF Bay, The Solent etc.). It is also especially helpful if using Expedition or Adrena for navigation/route planning as this seems to be the only way to get even the free data into the Nav software in a read-able format.

Unfortunately, it’s pretty expensive for occasional use or cruising-only needs (roughly $480/yr at today’s exchange rate), especially if you are outside the areas they have modeled. For example, on the Chesapeake Bay, I can pull the same current model up for free on the NOAA website (https://tidesandcurrents.noaa.gov/ofs/ofs_mapplots.html?ofsregion=cb&subdomain=0&model_type=currents_forecast). Unfortunately I can’t easily pull that into Expedition, so one has to do a little math on their own when bay racing, or pay for the Tidetech subscription.

 

I've been tinkering with this.  This page talks about a thredds server : https://tidesandcurrents.noaa.gov/ofs/cbofs/cbofs_info.html . It's possible to get a netcdf file from there.  Eg :

 

u0=https://opendap.co-ops.nos.noaa.gov/thredds/dodsC/NOAA/SFBOFS/MODELS/2021/08/28/nos.sfbofs.regulargrid.f048.20210828.t21z.nc

nccopy -V u_eastward,v_northward $u0 $(basename $u0)

 

... and then view that with ncview.  Might have to convert to grib for expedition.  NB : this includes 100 "depth levels".  Dunno how to get "nccopy" to only get the surface currents.

 

I've been working on a python / siphon script that will get surface data and plot it. Could probably be turned into a web page w/ Bokeh / Plotly / Altair.

 

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FWIW, my son has sailed the Bay extensively and has told me you can throw the published current tables right out the porthole every winter as the Bay is dramatically affected by the amount of snow runoff from the Sierras down the four large rivers which drain into it. 

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FWIW, my son has sailed the Bay extensively and has told me you can throw the published current tables right out the porthole every winter as the Bay is dramatically affected by the amount of snow runoff from the Sierras down the four large rivers which drain into it. 

Runoff can have a huge effect.....   but to say "throw the published current tables right out the porthole every winter" is a crock.  You do need to know if it's flooding or ebbing regardless.

 

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On 9/5/2021 at 11:26 AM, solosailor said:

Runoff can have a huge effect.....   but to say "throw the published current tables right out the porthole every winter" is a crock.  You do need to know if it's flooding or ebbing regardless.

 

Yeah.  Plus not much snowmelt runoff in winter. Rainwater yes, a few days after it rains

Rain runoff and snowmelt runs on top of the saltwater that the tide book tells you about.  The foils and most of the hull are still riding around I'm the salt water, so don't throw the tide book about the window just yet. 

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