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    Re: Voyaging the traditional way
    From: Carl Herzog
    Date: 2004 Nov 4, 09:21 -0500

    Regarding taffrail logs:
    
    I've used a large Lionel log extensively on a schooner I worked on that did
    educational voyages in the northeastern United States. I've also used
    Walkers extensively offshore on a couple similar vessels (tops'l schooner,
    brigantine; 120'-150' LOA; 9'-12' from the rail to waterline).
    
    On the coastal schooner, our biggest concern with the log was having the
    line to the rotator cut by inquisitive motorboats. Replacing these was
    particularly expensive and difficult, so we took to using bright orange line
    and hauling in the rotator in crowds.
    
    Offshore, we paint the rotator black. Unpainted metal glittering in the sun
    tends to turn the rotator into a fishing lure for sharks.
    
    Motoring up on to Silver Bank near the Turks and Caicos once, we were
    followed by a humpback whale who became quite enamored of our rotator,
    nudging and poking at it, for reasons I never understood. I assumed the
    vibration of the engines would have drowned out any hum from the rotator. We
    hauled it back before she got carried away.
    
    Anyway, a good taffrail log is usually very accurate, even in a following
    sea. A couple factors that contribute to accuracy, in no particular order:
    
    -- Speed. The ship has to be moving fast enough for the rotator to spin, not
    slip through the water or sink. This is a product of the size of the
    rotator, and to a lesser degree, the resistance of the line to twisting.
    Most of the ones I've used are pretty good as long as you can maintain about
    1.5 to 2 knots on average.
    
    -- Length of line. As George indicated, the line needs to be long enough to
    keep the rotator below the water. This is obviously a product of the height
    of the gauge above the waterline. However, you also want to keep it far
    enough away from the transom to minimize the turbulence from the ship's
    wake.
    
    -- Line material. The line's ability to transfer the twist from the rotator
    to the gauge is critical. Avoid anything stretchy; use braided, not
    three-strand.
    
    -- Calibration. The rotator must be designed for the gauge it's attached to.
    You would think was obvious, but as most of these are no longer produced,
    insuring accurate calibration in shoppping for spare parts can be a
    challenge. Additionally, any damage whatsoever to the fins on the rotator
    will render it virtually useless.
    
    -- Gauge condition. Keep the gears oiled and running smoothly.
    
    On a separate note, I've also used a chip log quite a bit on a historical
    replica vessel. This is a lot of fun, but a lot of work. It, too, can be
    surprisingly accurate, but definitely takes some practice. The rise and fall
    of the transom with the seas affected this far more than a taffrail log. We
    found that how the line spools off the reel was the biggest factor in
    determining how accurate we could get. The line needs to remain taut, but
    not so much so  that the chip is dragging through the water.
    
    Making sure the peg popped when you wanted to collapse the chip for
    retrieval -- but not sooner -- was also important not only to our accuracy,
    but to crew morale. At six knots, having to haul back the chip if the peg
    hadn't popped was a serious workout!
    
    
    Carl
    
    
    

       
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