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    Re: Noisy Sea Surface
    From: George Huxtable
    Date: 2003 Nov 15, 20:36 +0000

    My observations of noises from "clickers" off the South coast of England
    are similar to those of Keith Williams in New Zealand.
    
    That is: they are certainly individual clicks and not at all drawn-out
    "scrapes". They are heard from below decks, the sound being transmitted
    through the water and the hull, and not (or at least, very attenuated) from
    on deck. I have heard many clicks per second, but these seem to be from
    multiple sources, from all around the hull, not just from one or two
    clickers, clicking madly from one place.
    
    Often, sounds are heard from below, in the cabin, transmitted through the
    water, that would never be audible from the cockpit. For example, when the
    Navy is exercising nearby, what I presume to be anti-submarine sonar, with
    all sort of whistles and warbles. Or the rumble of the chains from a
    chain-ferry a mile or so away. I presume that if the sound has an
    undervater origin then it gets transmitted best underwater.
    
    I shouldn't give the impression that such clickings are predictable or
    frequent in our waters. I hear them only rarely, but most often from
    certain anchorages. They don't occur often enough to make for an easy
    research project.
    
    In Worbarrow Bay (a few miles East of Portland Bill), where I've noticed
    these clickings most often, there's an additional hazard when anchoring for
    the night. The shingle beach is a popular spot for night-anglers, who set
    up with an umbrella and a beach-casting rod. My anchoring spot is usually
    just about casting distance from the beach, but we have an anchor-light and
    they usually avoid us when casting. I mention this, because the presence of
    anglers usually (but not always...) denotes the presence of fish. I've
    never asked what they were after, though. Next summer, I will.
    
    My guess has been that the clicks came from lovelorn crustacea who are
    exploiting the sound-carrying properties of water to attract the opposite
    sex. But I have no real evidence to back up that hunch.
    
    I know that boat-hulls are attractive to certain fish, and my home berth
    (fishing not allowed) has a plentiful resident population of grey mullet,
    some really large ones. These graze, most efficiently, on the weed and
    fouling on the hulls, leaving a pair of parallel clean lines where their
    lips have tracked across. I doubt whether grey mullet make good eating at
    the best of times, but these must take in a good helping of antifoul with
    their diet, so I wouldn't fancy them.
    
    George.
    
    
    ================================================================
    contact George Huxtable by email at george---.u-net.com, by phone at
    01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    ================================================================
    
    
    

       
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