[C320-list] Genoa Size

[Scott Thompson]

You are absolutely right.  I don't know what I was thinking when I wrote 
that.  I somehow got the I and J measurements mixed up in my head. 
Thanks for the correction.

In any event, it won't be terribly useful to your sailmaker to just try 
to measure overlap with the mast.

Scott

Chris Burti wrote:
> Respectfully, a little clarification may be in order. Scott is precisely
> correct in his description of how to measure the LP. As an old PHRF racer, I
> believe him to be wrong as to what is generally accepted as to what the
> percentage measurement describes.
> 
> The percentage description for a Genoa as is generally used is derived from
> widely accepted measurement rules for handicap racing. these rules limit the
> size of the foresail by restricting it as a percentage of the foretriangle
> defined as a ratio of the LP to the J measurement. The J measurment is the
> distance from the stay to the mast at the deck. I quote from the PHRF rule
> that limits the maximum size of the Genoa where " the Genoa LP is between
> 150% and 155% of' J".
> 
> This ratio is unaffected in any by mast rake. Nor is it affected in any way
> unvaforable to the handicapping system by cut or clew height.
> 
> As a termendous volume of sails that are being built by local lofts of major
> sailmakers are built for PHRF racers, sailmakers most commonly use this
> accepted definition and it will be found on the better websites that include
> definitional material.
> 
> Scott may be refering to a system of measurement in effect that is less
> widely known, but I am totally ignorant of it and hence can't offer any
> insight.
> On Dec 14, 2007 3:46 PM, Kirk McCullough <kirk.mccullough at telus.net> wrote:
> 
>> So size does matter, but a lot depends how you measure it.
>>
>> Kirk
>> #124
>>
>> ----- Original Message -----
>> From: "Scott Thompson" <sthompson at toad.net>
>> To: "C320-List" <c320-list at catalina320.com>
>> Sent: Friday, December 14, 2007 7:01 AM
>> Subject: Re: [C320-list] Genoa Size
>>
>>
>> The "percentage" that sailmakers use to measure a sail is usually defined
>> to be the ratio of the "luff perpendicular" measurement to the luff
>> measurement (assuming a full hoist jib).  The luff perpendicular is the
>> distance from the clew to the luff, measured perpendicular to the luff.
>> The easiest way to measure this is with the sail off the boat and laid out
>> flat on a deck or lawn.  Simply fold the sail by pulling the tack along
>> the luff towards the head until the folded sail makes a right triangle
>> with the head at one corner, the clew at another corner, and one end of
>> the fold makes the third, right-angle corner.  Then the length of the
>> folded edge is your LP length and the percentage your sailmaker will use
>> is the ratio of this to the length of the luff itself.  This, together
>> with the luff length, determine the total area of the sail, assuming the
>> sail is triangular.
>>
>> Contrary to popular opinion, the percentage does not have anything to do
>> with the distance from the mast to the forestay, or the amount of overlap
>> with the mast.  The LP distance for a 100% sail can be longer or shorter
>> than the distance from the mast to the forestay, depending on how you
>> measure the latter, the cut of the sail, and what the rake of the mast is.
>>  A 100% sail with a very high clew might overlap the mast quite a bit, for
>> example, while one with a very low "deck sweeper" clew might have the tack
>> slightly forward of the mast.  Both would have the same sail area.
>>
>> Scott Thompson
>>
>>> I am also interested in the response to Brian's question. First though,
>>> how
>>> do I determine how big my existing sail is. Just measure the overlap at
>>> the
>>> mast verses the distance from the mast to the forestay. I also find our
>>> existing genoa hard to tack and two much sail allot of the time and
>>> partially reefing it gives a really poor shape. I have been leaning
>>> towards
>>> a 110 but perhaps a 135 would be the way to go to save some performance
>> in
>>> light winds. FX will make a 110 and 135 for $1299 and $1499 respectively
>>> and
>>> currently have a sale on for 10% off. Anyone have experience with their
>>> products? We don't race and are happy with dacron sails as long as they
>>> are
>>> well made.
>>>
>>> Darrell
>>> 88 Antares
>>>
>>>
>>> ----- Original Message -----
>>> From: "Amirault Family" <amiraults at sympatico.ca>
>>> To: <c320-list at catalina320.com>
>>> Sent: Wednesday, December 12, 2007 3:08 PM
>>> Subject: [C320-list] Genoa Size
>>>
>>>
>>>> Opinions solicited.
>>>>
>>>> Bear has a 150% foresail which can certainly be an aid when the 'boys'
>>>> are
>>>> racing her, but which is a bit much to handle for a spouse with limited
>>>> upper body strength who both wants to take part when gentle cruising
>> but
>>>> who refuses to take the helm. For those days with the mate when speed
>> is
>>>> not an issue, is a 135% small enough, or should I be looking at a
>>>> 120/125?
>>>>
>>>> I would like to here from those who are using 135% or smaller jibs on a
>>>> regular basis...or Adam
>>>>
>>>> Regards;
>>>>
>>>> Brian Amirault
>>>> 797 Waltzing Bear, too
>>>>
>>>>
>>>
>>>
>>
>>
>>
>>
>> --
>> No virus found in this incoming message.
>> Checked by AVG Free Edition.
>> Version: 7.5.503 / Virus Database: 269.17.2/1184 - Release Date:
>> 12/14/2007
>> 11:29 AM
>>
>>
>>
>>
> 
>