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35735Re: Cowl Vents - 4" with a little extra work?

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  • JohnF
    Jan 5, 2012
      We made a decision - At the end of the day aesthetics trumps fluid dynamics. On a piece of paper we laid out the footprint of the original deck flange, a 3" flange, and a 4" flange (based on Vetus measurements). It's pretty clear that the 4" flange will barely fit on top of the dorade box. It will go right up to the edge, and that it wouldn't look "right". We are going with the 3" ...

      JLF

      --- In Sabresailboat@yahoogroups.com, "JohnF" <jl_folk@...> wrote:
      >
      > The old original Martec cowl vents were removed yesterday on our 1987 34 MkII (thank you 55 degree Maryland weather!). In reviewing the archives, it looks like most people have replaced with 3" cowl vents, often requiring a teak or starboard 'pad' to accommodate a smaller deck ring.
      >
      > Has anyone gone to the effort to slightly modify the dorade box to install 4" vents? The holes in my deck are 3 11/16 inches, somewhat bigger than is needed for a 3" vent, and slightly smaller than is needed for a 4" vent.
      >
      > It's tempting -- the 4" vents are only an inch taller (so I don't think they would look out of scale), but have 40% more air flow capacity (based on Vetus catalog).
      >
      > I don't see any references to this approach, so am suspecting that there is a hidden 'gotcha !!!'.
      >
      > Thanks -
      >
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