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Wave height calculation

Old 01-25-2021, 02:53 PM
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Default Wave height calculation

We boat in Galveston bay and the Gulf most of the time. I use the Ventusky app for wind and wave height to decide our destination based on my passengers ie granddaughter's and so on. That said we went out a while back and my app said wind wave height was 1.2 footers so pretty flat. When we hit the bay they were 3 footers plus Surprise. I noticed there is a selector on the app for wind wave height and swell height and spacing. Am I to assume that wind wave height is calculated on top of the swell height. So to accurately assess conditions they need to be added together? I look at conditions like wind direction as it changes where we launch
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01-26-2021, 11:47 AM
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Unless you boat on LOTO or Mead there shouldn’t be a need to be concerned with wave height.
Old 01-25-2021, 09:14 PM
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Donít forget, most people look at a wave and say itís 4í from the bottom of the trough to the top of the wave so itís a 4í wave. I reckon thatís incorrect, itís a 2í wave. The sea level is usually slightly below the middle, between the trough and the peak and a true wave height is the height above that median level. (The trough generated by wave action is not part of the wave)

Maybe your App calculates it the true way so their 2 footer might be seen by most as a 4 footer?

RR
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Old 01-26-2021, 09:06 AM
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Oh boy! This should be good.
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Old 01-26-2021, 11:08 AM
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Double post

Last edited by thisistank; 01-26-2021 at 11:23 AM.
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Old 01-26-2021, 11:09 AM
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Originally Posted by Sstevens11 View Post
We boat in Galveston bay and the Gulf most of the time. I use the Ventusky app for wind and wave height to decide our destination based on my passengers ie granddaughter's and so on. That said we went out a while back and my app said wind wave height was 1.2 footers so pretty flat. When we hit the bay they were 3 footers plus Surprise. I noticed there is a selector on the app for wind wave height and swell height and spacing. Am I to assume that wind wave height is calculated on top of the swell height. So to accurately assess conditions they need to be added together? I look at conditions like wind direction as it changes where we launch
I use surf-forcast.com and it is usually spot on but like weather forecasting predictions can be wrong and you could have caught a bad day.

Originally Posted by rak rua View Post
Donít forget, most people look at a wave and say itís 4í from the bottom of the trough to the top of the wave so itís a 4í wave. I reckon thatís incorrect, itís a 2í wave. The sea level is usually slightly below the middle, between the trough and the peak and a true wave height is the height above that median level. (The trough generated by wave action is not part of the wave)

Maybe your App calculates it the true way so their 2 footer might be seen by most as a 4 footer?

RR

I don't think that's accurate. Swell height from every scientific chart I've ever seen measures from the bottom of the trough through the point of sea level (like you're stating approximately mid section) to the crest.





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Old 01-26-2021, 11:47 AM
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Unless you boat on LOTO or Mead there shouldn’t be a need to be concerned with wave height.
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Old 01-26-2021, 11:50 AM
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On Lake Michigan wave height can vary mile by mile and minute by minute . Looking at a "wave forecast" is about as accurate as the covid numbers.
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Old 01-26-2021, 12:40 PM
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Originally Posted by ICDEDPPL View Post
On Lake Michigan wave height can vary mile by mile and minute by minute . Looking at a "wave forecast" is about as accurate as the covid numbers.
It's a good tool to get wave height info but, yes, it can change rapidly especially on western Lake Erie and the St. Clair River if the wind starts blowing north! It also doesn't mean much when you are in a washing machine which is pretty much what Lake Erie looks like sometimes.
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Old 01-26-2021, 02:21 PM
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i use https://www.ndbc.noaa.gov/ you can zoom in and click on the actual buoy in your area and see what the wave height and time between waves is at hourly intervals.
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Old 01-26-2021, 02:26 PM
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Originally Posted by 47EXCALIBUR View Post
i use https://www.ndbc.noaa.gov/ you can zoom in and click on the actual buoy in your area and see what the wave height and time between waves is at hourly intervals.
How can I do that using a phone?
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