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post #8 of Old 07-31-2009
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I am not sure why you feel the need to dig up old threads and attempt try to nitpick my postings but I will attempt to respond to a couple of the points raised in your post above and perhaps correct some of your misunderstandings.

When you say," A fin keel is by definition a keel separated from the rudder. The Contessa 32 with a skeg mounted rudder is still a fin keel design. Any and all proportions of fin keel with a separate rudder is still a fin keel." You are citing but one currently popular definition of fin keel but not a totally accurate one either in contemporary colloquial use or historically speaking as I will explain below.

You obviously came to the sport later than I did because when I began sailing in the early 1960's what distinguished a fin keel from other keel types was souly the length of the keel on its bottom relative to the length of the boat. Obviously that definition has changed in common usage.

In responce to your perhaps rhetorical quandry: "I don't know where this "A keel whose length on it bottom is 50% or less of the LOA or length of sail plan which ever is longer"" That was the oft cited popular definition when I was first exposed to sailing in the very early 1960's. It was used or included in sailing primers, yacht design books of the day, and in yacht design courses of that era. (Although earlier references usually referred to the length of the sail plan and later references to the LOA.)

In those days, the hull forms of a fin keel boat were not all that different from the hull forms of a fuller keeled boat, both had slack bilges and wineglass sections and so any other form of distinction was harder to make.

In those days, boats like Allberg 30 were described in their early literature as having 'a modern fin keel' even though we all knew that they had attached rudders, and in the early 1960's, magazines routinely described boats like Dragons and early 'meter' class boats as fin keel boats regardless of whether they had attached rudders or not. It was the definition within Westlawn courses of that era.

Obviously the definition of a fin keel being defined by the length of the bottom of its keel has fallen out of popularity, but it has not really been replaced by as clear a definition today. I respectfully suggest that your definition above "A fin keel is by definition a keel separated from the rudder." or to say, "Any and all proportions of fin keel with a separate rudder is still a fin keel." is not inherrently correct. While your personal definition of a Fin Keel is used by some people today, that definition does not necessarily totally jibe with current usage either. For example, Island Packets have post-hung, spade rudders rather than keel hung rudders and yet they are typically referred to as having a full keel. You also see some more moderate fin keel/skeg hung rudders referred to as 'full keels with a Brewer bite'.

As to the explanation and example that I wrote above regarding Capsize Screen Formula and the Motion Comfort, I have used that before and while I may infact be an amatuer, the respected designer Robert Perry responded to nearly that exact quote with;
Many thanks for your common sense approach to this subject. I have been harping on the same thing for years."
The Uselessness of the Capsize Screen Formula and the Motion Comfort Index. - Anything Sailing Forums

The one thing that you and I do agree on is "Sometimes a little knowledge is a dangerous thing."


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Last edited by Jeff_H; 07-31-2009 at 04:22 PM.
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