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Sail & Rigging - Forestay cable diameter swan 44
16 March 2016 - 19:41
#1
Join Date: 12 March 2013
Posts: 24

Forestay cable diameter swan 44

Dear All and Lars,

I'm changing my furler on Solano, a swan 44 and I'm thinking of changing size of the cable for forestay which is 10 mm today. What is the orginal diameter for the cable of the forestay and do you think that I should go for 12mm ? Ringing and sail plan are original.

Thank to all and fair winds,

César

16 March 2016 - 20:08
#2
Join Date: 29 January 2007
Posts: 1018

Dear Cesar,

S&S sail plan says the original diameter is 9 mm.

I think 10, and if Dyform, would be certainly enough

Fair winds!

matteo (47/069 Vanessa)

17 March 2016 - 08:08
#3
Join Date: 02 January 2008
Posts: 1547

Dear César

I think Matteo's suggestion is on the safe side, but it should be noted that the forestay sees more load than is applied in the backstay.
One reason is that the angle between the forestay and the mast is smaller than for the backstay. This trigonometry factor for the 44 is 1.23, and to this the effect of a hard sheeted mainsail needs to be added. The mainsail leach pulls the masthead aft, and this increases the load in the forestay further.
I would like to ask which size the backstay is, and does it have a hydraulic tensioner?
Do you feel that the forestay is sagging too much?
Kind regards
Lars

 

17 March 2016 - 09:17
#4
Join Date: 12 March 2013
Posts: 24

Dear Lars and matteo,

Thank your answer.

Diameter of the cable for backstay is 10mm and i use hydraulic tensioner (original one)

The tension on the forestay is not so much but solano is quite fast like this.

 

I ll think that 10 mm should be enough.

 

Again tk to both of you,

César

18 March 2016 - 20:10
#5
Join Date: 19 October 2012
Posts: 44

Hi Cesar and everybody,

I've studied that issue with my rigger 2 years ago and We decided to use a 10mm 1x19 (not Dyform).

See you regating soon...

Alberto

Pippus 44-011

19 March 2016 - 07:47
#6
Join Date: 05 August 2010
Posts: 162

Dear César and all,

I remember there was a thread on rigging which warned against the use of Dyform in combination with a hydraulic tensioner. I checked - the thread started 12.10.12 and there were some references to Dyform possibly unwinding under high tension, including one reference to Navtec.

If that information is out of date, this would be a good place to confirm (as would be the older thread).

Fair winds,

Martin (Age of Swan, 48/039)

19 March 2016 - 08:19
#7
Join Date: 02 January 2008
Posts: 1547

Dear Martin

Thank you for this observation
Dyform can very well be used in the forestay, as the ends cannot rotate, but should be avoided in the backstay if there is a hydraulic tensioner. The tensioner piston rod can rotate, and this allows the Dyform to unwind itself under high loads.
 
It can also be commented that Dyform has rather sharp corners on the strands, and if used in shrouds this will eat the sail stitchings.
Kind regards
Lars

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