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    Re: on finding Pitcairn Island
    From: Robert Gainer
    Date: 2004 Sep 21, 18:43 +0000

    Trevor,
    I think that for the most part a wave will not feel the bottom until the
    depth of water is less then � of the wavelength. At that point you will
    begin to see some difference in the wave pattern.
    All the best,
    Robert Gainer
    
    
    
    >From: "Trevor J. Kenchington" 
    >Reply-To: Navigation Mailing List 
    >To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    >Subject: Re: on finding Pitcairn Island
    >Date: Tue, 21 Sep 2004 11:45:56 +0000
    >
    >Peter Fogg wrote:
    >
    >>What is found between New Zealand and Australia are a number of underwater
    >>sea mounts, mountains
    >>that rise from the sea floor about 4000 metres below to within a
    >>comparitively short distance, some of
    >>them, from the surface. When the sea is agitated the area above the mounts
    >>has a different characterisitic
    >>compared to the open ocean, and could lead to speculation; such as land
    >>being near.
    >
    >
    >Could Peter elaborate on his sources for the contention that the sea
    >surface gets a detectably different "characteristic" above a seamount?
    >
    >I have a very little experience fishing over seamounts in the general
    >area in question, though rather further south (around 49 degrees
    >latitude). We certainly had times down there when the sea was agitated,
    >as would be expected, but nothing that suggested to me that land was
    >anywhere near. [In my case, the summits of the seamounts were around 700
    >metres depth. They stand on the South Tasman Rise at around 1400, while
    >the surrounding area is 4000 metres or so in depth. Clearly, a seamount
    >which comes very much closer to the surface would be more likely to have
    >effects visible to a surface observer.]
    >
    >Of course, we had SatNav and charts to tell us that land wasn't close,
    >plus a powerful sounder to tell us just how deep the water was, and thus
    >were not looking for subtle signs. Add in an enclosed wheelhouse and
    >work to do that kept me from watching the sea all day long: Maybe there
    >were features in the wave patterns that a sailing-ship master, running
    >his easting down across the same area, would have observed.
    >
    >
    >Trevor Kenchington
    >
    >
    >--
    >Trevor J. Kenchington PhD                         Gadus{at}iStar.ca
    >Gadus Associates,                                 Office(902) 889-9250
    >R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    >Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
    >
    >                     Science Serving the Fisheries
    >                      http://home.istar.ca/~gadus
    
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