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A question about measuring wave height.


Old Ironmaker

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A good question that was posted on another site. When Marine Weather Service here reports 1 to 1.5 meter waves I don't see 12 footers out here. No way I go out in 1 meter seas if I know the height is 9 feet or whatever the conversion is from below flat to above flat. No way. This was the question:

 

 

"In the thread about followings seas I was wondering how people measure wave or sea height. My understanding is a 4' sea is 4 feet above flat which gives an 8' wave. I know surfers confuse it by measuring height from the front in some areas and the rear or even "surfable wave height". On a TV episode of Wicked Tuna most would not go out in 4-6' seas. I assumed that was because a 12 foot wave from trough to crest was possible. Throw in a narrow inlet or a rouge taller wave and that makes a 4-6' sea not navigable for a lot of those large experienced tuna boats. So what is your understanding and who exactly is calling a 4' sea on the marine radio?"

Edited by Old Ironmaker
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They are saying a 4 foot wave is 4 feet to the bottom of the trough i.e. below flat and 4 feet to the crest, above flat which makes it a 8 foot wave.

 

I bet I'm on the water more than in the NWT's. We don't have to wait until mid June for the ice to melt, ha, gotch ya.

 

I don't know about that OI. I spent over 10 years chartering on Lake Ontario before I moved up here. :whistling:

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They are saying a 4 foot wave is 4 feet to the bottom of the trough i.e. below flat and 4 feet to the crest, above flat which makes it a 8 foot wave.

 

I bet I'm on the water more than in the NWT's. We don't have to wait until mid June for the ice to melt, ha, gotch ya.

My Google search seems to support the trough to crest. Appearently they generally about half the height that most people would estimate.

 

http://www.boatingmag.com/how-to/measuring-wave-height

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I was always told that ocean waves were measured from mean ocean level to crest and that lake waves were measure trough to crest but from the research I have done this morning this is incorrect. It seems that all official wave measurements are trough to crest. That said, the government weather buoys on Lake Erie sure seem to read about half of the actual wave heights based on my experience but that again could be the 'perception phenomenon' discussed above. Another key thing I noticed while researching things was that the NOAA and Env Canada wave heights are 'average' wave heights and that statistically speaking, waves up to 1.84 times this height are likely to be mixed in. Based on my experience, I don't go on Erie any more unless the weather buoy wave readings are 2.3ft or less and predicted to drop.

Edited by G.mech
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What I know is most guys call 2 footers 6 footers. LOL

 

S.

 

 

LOL, no kidding.

Now a days I really don't like going if the waves are going to be 3 feet or bigger.

Gettin' old and I like being comfortable when I'm out now. ;)

Depending on the lake though waves are not created equal.

A 3 footer on Lake Ontario is usually much nicer than a 3 footer on Erie. B)

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I don't know about that OI. I spent over 10 years chartering on Lake Ontario before I moved up here. :whistling:

Does hanging out, I mean supervising the unloading of the CSL lake freighters for the better part of a 12 hour shift for around 5 years count as hours on the water? Most of that time was in the Galley scarfing down some really magnificent food to be totally honest. A great experience until you had to climb down the hoop ladder into a hold or dock the boat in all kinds of awful weather up until Christmas some years.

 

I won't even bother going out when I can see whitecaps on the horizon now. If I am invited out in one of the larger boats of 28 feet or more in a tournament 3 footers, I mean 6 footers aren't really a problem. The problem is that they are not all just 6 footers especially with wind speeds increasing, that's when I say thanks but no thanks. Otherwise whitecap days are golf days.

 

Good to learn how to properly id wave height, thanks all.

Edited by Old Ironmaker
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