[C320-list] mast

[Scott Thompson]

First, steel wire does stretch.  Read any good book on rigging design 
and it will provide you with specs for how much.  But it doesn't stretch 
much, and when you tension the backstay the main effect on the forestay 
is to remove sag, which can dramatically affect the shape of the genoa 
by flattening it and moving the draft forward.  You can see this by 
sighting up the forestay while close hauled.  The forestay sags quite a 
bit, but the amount is adjustable with backstay tension.

Yes this also increases compression on the mast, which is already 
significant when sailing upwind because of tension on the windward 
shrouds.  That's why 320s have that compression post in the middle of 
the main cabin.

I'm fairly confident that the effect on genoa shape from adding backstay 
tension is much more important than any effects on mainsail shape on a 
320.  You can bend a 320 mast, as others have pointed out, but not 
nearly to the extent that you can with a true fractional rig and a keel 
stepped mast.

John Van Vessem wrote:
> Steve,
>    
>   I never understood how you can move or bend the top of the mast since the head stay and back stay counter each other.  To bend  the mast you would have to stretch the head stay.  Although there is a certain amount of stretch in steel cable, I think what you are really doing is pushing the mast down.
>    
>   John (Sojourn 645)
> 
> Steve Magennis <magenns at yahoo.com> wrote:
>   While that's true (the tapered top IS slightly lighter than an
> untapered top), the taper also allows us to SLIGHTLY bend (not rake)
> the top of the mast with a backstay adjuster (if the forward lowers are
> tight) and SLIGHTLY depower the main (the bend sucks a little cloth out
> of the belly of the main).
> 
> I don't think either reason is significant.
> 
> Steve
> Alchemist #909
> 
> --- David Gleason wrote:
> 
>> I
>> believe the reason the top of the mast istaperedd is to reduce the
>> weight aloft.
>>
>> Dave Gleason
>> Proud Mary, #150
>> On Mon, 22 May 2006 11:35:48 EDT JBrown5093 at aol.com writes:
>>> Thanks for the information. This list is always helpful. Jim Brown
>>>
>>>
>>
> 
> 
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> 
> John Van Vessem
> Sojourn 645
> Vallejo Yacht Club