Beuford Scale and waves

Discussion in 'All Things Boats & Boating' started by Fanie, Jan 15, 2008.

  1. Fanie
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    Fanie Fanie

    A comment below the beuford scale I have suggests that closer to shore the waves become smaller and steeper.

    Can anyone pls indicate how much is smaller and how much is steeper ?

    If one have an idea of the water 'size" close to shore it would then be an indication of what to expect if you venture further off-shore ?
     
  2. TeddyDiver
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    TeddyDiver Gollywobbler

    Not smaller, steeper yes. Shorter and steeper. The amount of water in a wave is about the same wheather its deep or shallow. Someone will certainly give a formula of the behavior of waves, but meanwhile I quess the wave length can't be longer than the depth...
    maybe
     
  3. safewalrus
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    safewalrus Ancient Marriner

    how long is a piece of string?

    Fanie you may as well have asked the above - it gets smaller and shorter and steeper as you run out of water (just as wild and nasty, just less water to make up the waves is all) at the waters edge its bugger all! Just that the waters edge keeps moving (often dramatically)! Depending on the strength of the wind!
     
  4. Kay9
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    Kay9 1600T Master

    An aside note:
    Im my training as a coxswain in the CG for landing craft I was taught that when you see the wave break on the beach, the distance from the trough to the top of the wave is the same distance or depth from the trough to the bottem. Hope you never need to use this info, but handy to know, if your beaching.

    K9
     
  5. safewalrus
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    safewalrus Ancient Marriner

    Trouble is by the time you've figured this out you're "broached" and in deep poo!
     
  6. Kay9
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    Kay9 1600T Master

    Here in Oregon we have to ride breaking waves quiet often. Just the way the Bars are here on the coast.

    But I agree, if im in poo I generally poo myself.

    K9
     
  7. Trevlyns
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    Trevlyns Senior Citizen/Member

    Wot? It gets smaller and shorter?

    Is that in direct proportion to the amount of prune juice consumed?

    NOW I know the cause of my problem! :D
     
  8. Fanie
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    Fanie Fanie

    Maybe I should ask the Q differently.

    What is the difference in waves close to shore (not IN the breakers) and the ones in the deep sea (offshore) ?
     
  9. Guest625101138

    Guest625101138 Previous Member

    Use the formula shown here and do it yourself:
    http://hyperphysics.phy-astr.gsu.edu/Hbase/waves/watwav2.html

    I feel I have been in wave crest with steeper than 120 degree included angle when running past a moored ship held beam on at a deep berth. The waves were almost like water fountains with very pointed crests. So take the sketches provided at the bottom as "ideal" worst case. I am sure things can get worse under odd situations. I have seen 3ft standing waves in a tidal run and these are on the verge of breaking while going backwards over the ground.

    Water can do some interesting things and they get more interesting as your boat gets smaller.

    Rick W.
     
  10. Kay9
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    Kay9 1600T Master

    Intresting isnt the word I would use :)
     
  11. charmc
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    charmc Senior Member

    Fanie,

    Great question!

    From a practical point of view, it's the "shape" of the wave that changes as it goes from deep to shallower water. They sort of "pile up" as they approach the shore, becoming closer together and steeper. Out at sea, 1 m swells might be 200-300 m apart, easy to ride over sometimes barely noticeable. As those same swells approach the shore, they get closer together and steeper. 1 m waves that are close to vertical and 20-30 meters apart can cause a very rough ride. The same waves have just changed their shape and piled up closer together, but that makes their effect on a boat very different.

    Hope this helps.
     
  12. Frosty

    Frosty Previous Member

    Its all guide lines,--rules of thumb etc. 1 in 7 works some days and some others you get blocks of 3.
    Going in shore usually will have choppier conditions. People have spent years trying to work out waves and put it on paper.

    Why do you ask the question?
     
  13. Fanie
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    Fanie Fanie

    Uncle Frosty, I'm asking because from a shoreline you can see the water behind the waves and the breaking waves - and how rough conditions are... assess the conditions instead of assuming. If you dump the boat in the water and by the time you hit the chop it may be a bit late...

    Charlie, nice answer thank you, that was what I was suspecting, but I wanted to make sure. It makes sense, when the water becomes shallow, wave speed may be slowing down due to the less place for the water so to speak, so the waves become closer to one another. Then when shallow enough the wave's water becomes too high to remain 'stable' and a breaking wave result. The 'lay of the land' thus hugely effects this and determine how the wave outcome would be.

    So can I to some degree assume that if the shoreline conditions are overcome-able that one would have more livable conditions in deeper water further off-shore that is more comfy ?

    What is 'White Water' ?
     
  14. safewalrus
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    safewalrus Ancient Marriner

    In a word "Yes" - all you gotta do is get out there!

    water that is white! i.e. when it's blowing a hooligan lots of air gets mixed up in the water and the tops get white (nasty) OR when the water is running fast over close to the surface rocks and the like, the same effect happens - simple really! Next time it's blowing a hoolie go see (but I wouldn't advise trying to go out)

    Don't you know some smart assed gentleman is going to shoot me down - there's an answer to that but it ain't polite - try and you'll maybe get it!!
     
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  15. charmc
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    charmc Senior Member

    Yup. That's why standing orders for every nation's naval vessels is to put out to sea when a major storm approaches a base.
     
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