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Sail & Rigging - Swan 44 Headstay
25 February 2014 - 00:06
#1
Join Date: 19 October 2012
Posts: 44

Swan 44 Headstay
Dear Lars,
During my last solo winter cruise while reducing the genoa under F9 wind, I broke the old Hood furler.
Now we are planning to change it with an Harken MKIV.
Unfortunately we discovered that the unit3 suitable for 12mm wire Headstay costs much more than unit2 for 10mm wires. Our rigger decided in fact to install one year ago a X19 wire 12mm Headstay while back stay and shrouds wires are all of 10mm.

In the Nautor's sailplan the whole rigs were wires of 9mm.

I would substitute the 12mm Headstay with a 10mm. In order to install the Harken unit2 .
I know that the Headstay works with a narrower angle than the back stay with bigger forces involved but Nautor indicated a breaking limit of 16500 lbs. and the X19 10mm wire has a breaking limit of 84kN that is 8500kg = 18739 lbs.
so quite a stronger strength than what Nautor suggested 40yrs ago.

Do you agree with me or it's always better to have a stronger Headstay ?

Thanks for your help.

Alberto
(Pippus 44/011)

25 February 2014 - 11:13
#2
Join Date: 02 January 2008
Posts: 1547

Dear Alberto
I looked again at your excellent cruise video, and it appears there is no hydraulic backstay tensioner on Pippus. If this is the case 10 mm headstay would be OK. 9 mm is not used much, often it is 9.5 mm or actually 3/8 inch.
It is, however, suggested that you check two things to see if the 12 mm headstay can be used with a Unit 2 furler:
- if the pin sizes and terminal thicknesses on your present headstay are 16 mm or can be made compatible with that
- if the foil connectors accept 12 mm wire, or can be modified slightly for that, provided this is allowed by Harken.
If there is a 10 mm headstay with a hydraulic backstay tensioner the pressure needs to be limited in order to avoid overload.
Kind regards
Lars

25 February 2014 - 13:50
#3
Join Date: 19 October 2012
Posts: 44

Dear Lars,
We do have the original short Krugmann hydraulic tensioner at back stay .

Which tension you think can be acceptable for a safe cruise even with Strong winds (F9/F10).
I sail even most in winter than in summer!

;)

Thanks a lot for your always fast reply.

Alberto
(Pippus 44/011)

25 February 2014 - 16:01
#4
Join Date: 02 January 2008
Posts: 1547

Dear Alberto
You are right, the Krueger backstay tensioner is visible very briefly in your presentation.
A few technical questions:
It appears you have a mainsheet tackle without a winch, and this reduces the headstay load slightly, the tensioner can compensate for that. How much do you maximally pull on the mainsheet, and how many parts are there on the tackle?
Is the stemhead chainplate of aluminium, and have you checked it carefully for cracks?
What is the SWL your rigger proposes for the 10 mm headstay? Would suggest 35% of the breaking load.
What loads have you used on the backstay tensioner so far?
Kind regards
Lars

25 February 2014 - 19:15
#5
Join Date: 19 October 2012
Posts: 44

Dear Lars,
I reply to your questions in order:

1. How much do you maximally pull on the mainsheet, and how many parts are there on the tackle?
R: We have a winch too but we never use it, the tackle is more practical but I do not know which force we apply in it when pulling the mainsail...the boom lower max of about 40/50cm.

2.Is the stemhead chainplate of aluminium, and have you checked it carefully for cracks?
R: is an Inox and no crack until now

3.What is the SWL your rigger proposes for the 10 mm headstay? Would suggest 35% of the breaking load.
R: no suggestion, he says that it's not coherent to have a 12mm Headstay while the high sprouts are always 10mm. As far as I know applications where men are not involved, a safety factor 3 is compulsory. So as you suggested not more 3tons tension on a 10mm 1x19 Inox wire.

4.What loads have you used on the backstay tensioner so far?
R: this is what I would like to know as far as the load gage on the Krueger is not legible and are visible just unit number 1,2,3,4,5,6 but I do not know the references of this values. do you?

Thanks again Lars,

Alberto
(Pippus 44/011)

25 February 2014 - 20:42
#6
Join Date: 02 January 2008
Posts: 1547

Dear Alberto
Thank you for the information.
The numbers on the tensioner gauge represent "Tension lbs x 1000", this is stated on the lower part of the gauge, but apparently the text has faded in your case.
My estimates suggest that you should not use more than 4 on the wind in 25 knots true and over, how does this feel? In less wind use a lower number in proportion to wind speed.
It needs to be pointed out that if you sail with spinnaker in broaching conditions you should release the backstay tension, as otherwise the high stay loads in combination with the long topmast may bend the top to the side.
Kind regards
Lars

25 February 2014 - 23:35
#7
Join Date: 19 October 2012
Posts: 44

Thanks Lars.
I usually sail with a tension between 3 and 4.

So at the end you agree with me in changing the Headstay 12mm with a 10mm, keeping tension not more than 2000kg (tensioner at max 4000lbs.)?

Alberto
(Pippus 44/011)

26 February 2014 - 10:45
#8
Join Date: 02 January 2008
Posts: 1547

Dear Alberto
Yes, 4000 lbs is 1800 kg in the backstay, but due to geometry and mainsheet loads the headstay load can be up to 60% higher. A 10 mm wire can cope with this.
Kind regards
Lars

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