[C320-list] Jib Sheets Jamming - only a symptom

Sat May 20 11:15:29 PDT 2006

I just heard a great talk by economist Steven Levitt at a conference I attended last week, he wrote "Freakanomcs", makes mainstream economists seem pedestrian y comparison... :)

cuba libre 2
--------------------------
Regards,
OD

Sent from my BlackBerry Wireless Handheld

----- Original Message -----
From: C320-List-bounces
Sent: 05/20/2006 11:03 AM
To: C320-List <C320-List at catalina320.org>
Subject: Re: [C320-list] Jib Sheets Jamming - only a symptom

Actually I'm an economist, but since all economists are former or 
wannabe physicists these days, I've read a lot about rigging design and 
maintenance.

Scott

John Van Vessem wrote:
> Scott,
>    
>   You're a true engineer, and I agree with every one of your points.
>   John (Sojourn 645)
>
> Scott Thompson <sthompson at toad.net> wrote:
>   Only the first solution listed below -- narrowing the span of the toggle 
> and using a shorter clevis pin -- actually solves the underlying 
> structural engineering problem. Don't forget that the reason the jib 
> sheets jam is because the toggle is not properly sized for the chain 
> plates in the first place and so the jib sheets get caught under the 
> excess span of the clevis pin. This structural problem could have more 
> serious consequences for the rig, because it leads to either uneven 
> loading on the two sides of the toggle or an unsupported bending load on 
> the clevis pin, or both. I don't know if this is actually a problem, 
> since the toggle and clevis pin might very well be overbuilt for the 
> application. But I'd keep an eye out for signs of bending, distortion, 
> or stress cracks on both the toggle and the clevis pin.
>
> Covering these parts with tape or plastic or leather isn't very good for 
> them either, because these can retain moisture, and stainless tends to 
> corrode faster when exposed to stagnant, poorly oxygenated water. If 
> you cover them up, be sure to regularly remove the covering to inspect 
> for corrosion.
>
> To the person who asked what a toggle is, it's the inverted U-shaped 
> piece of metal that attaches the bottom of the turnbuckles to the 
> chainplates. The design allows for flexibility in the connection by 
> letting the turnbuckles pivot fore-aft on the clevis pin and laterally 
> on the toggle. This lets the shrouds, turnbuckles and swages line up 
> with their primary loads and not be subjected to bending loads, which 
> would otherwise lead to premature failure.
>
> Scott Thompson
> Surprise, 653
>
> Stanley Rogacevicz wrote:
>   
>> A third is to insert a small block of wood between the clevis and
>> chainplate on the inboard side to keep the clevis inboard and also place
>> a small block between the clevis and the deck to make an absolutely hump
>> free transition from deck to clevis on the outboard side then wrap the
>> whole thing with tape. The very smooth transition from deck to clevis on
>> the outboard side is shown in the picture on the c320 site I mentioned
>> the other day but the block to keep the clevis in place inboard is not
>> visible.
>> Stan
>> (formerly) Christy Leigh
>> c320 #656
>> Wickford/Narragansett Bay RI 
>>
>>     
>>>>> jvanvessem at sbcglobal.net 5/12/2006 10:38 AM >>>
>>>>>           
>> Richard,
>>
>> I have seen two solutions to this problem. One is to squeeze the
>> clevis togeather with a channel lock and insert a shorter pin. The
>> other is to insert washers to fill up the space between theclevis.
>>
>> John (Sojourn 645)
>>
>> "Richard A. Walker" wrote:
>> I have from time to time a problem with my jib sheets jamming under
>> the
>> shroud turn buckles on the deck. What seems to be the obvious solution
>> is
>> to put 1" vice the 2" clevis pins. 
>>
>> Has anyone made this change?
>>
>> Cheers,
>>
>> Dick Walker
>> C-320 (687) WindWalker II
>> 740 Olive Ave.
>> Coronado, CA 92118-2136
>> 619.435.8986
>>
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>>
>>
>> John Van Vessem
>> Sojourn 645
>> Vallejo Yacht Club
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>
>
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>
>
> John Van Vessem
> Sojourn 645
> Vallejo Yacht Club
>   

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