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Cambered panel sails on Ti Gitu

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  • 06 Dec 2011 19:03
    Quote
    Reply # 767248 on 766440
    Anonymous member
    Perfect, Arne!
    No links = text inside the frame.
    Links = potential trouble if the link is too long

    It's as simple as that. Nothing to do with software used.

    Please, guys, stop derailing these topics by wandering off into computer-related subjects. 
    Please, start a new topic in the Bar, where you can talk in acronyms until the barman gets tired and throws you out.
  • 06 Dec 2011 18:53
    Quote
    Reply # 767237 on 766440
    Anonymous member (Administrator)

    Paul and Edward.

    Now I'll try to paste in my letter above once more, after it has bee changed to .txt format.

    I fix a bit on it in this editor:

    *************************************

    Stavanger Tuesday
    This is most interesting!
    Ti Gitus problems:
    Ti Gitu’s sails are very high aspect ratio and well outside my experience. Still from what I’ve seen on sheeting my friend’s schooner “Samson”, it appears that problems soon get bigger with steeper and steeper sheeting angles. To get a better sheeting of the fore-sail (and maybe main too, I think I would consider trying a rail-to-rail sheethorse and thus sheet the sails from the weather rail.
    Paul Fay wrote :

     ”2/ Also that the boom/ bottom panel needs to be cut short to stop the sheet catching there as well.”
    Yes, I cut off 4-5% of the boom at the clew to avoid these problems on both Johanna and Broremann.


    Hong Kong parrels bending the battens:
    I too experienced this early on my Malena in 1994 (Batten 3 from top). Malena had a luff hauling parrel which worked on most of the luff. Later I found on Johanna that if I only use a luff hauling parrel on the yard and batten no 3, the sail below will be next to balanced with respect to weight. The Hong Kong parrels are then reduced to light trimming lines with no hard load on it. On both Johanna and Broremann I often see that the HK parrels are pretty slack, but they harden up a bit when I sail close-hauled. In fact, when Sebastian Hentschel (with plenty of offshore experience) made his new sail for Peregerine (front cover NL 57), he too just fitted this top luff hauling parrel and dropped the HK parrels altogether. The fanned sail of Fantail I’m no so sure about since I’m not used to it, but I have to remind you that the Hong Kong parrels were seen on just this kind of sails – in Hong Kong.


    Preliminary conclusion:
    It could well be that I’m too optimistic about cambered panel sails for offshore use, but it could also be that the problems on Ti Gitu stems from other reasons; high AR, steep sheeting, under-engineered battens etc. The matter of scantlings has to be dealt with in that other thread about sheets and battens. There seems to be may thin battens out there...
    Cheers,
    Arne

    **********************************************

    That was it. Does this too get outside the frame??

    Arne

     

    Last modified: 16 Mar 2022 09:57 | Anonymous member (Administrator)
  • 06 Dec 2011 17:20
    Quote
    Reply # 767176 on 767109
    Anonymous member
    Edward Hooper wrote:Hei Arne,
    We are losing at least 6 or 7 letters from each line of your comments here as well.
    Why does Wild Apricot do this to your comments, and does not appear to do it to others?
    Can someone, maybe David or Paul Thompson throw some light on this??????

    Edward, as I understand it,Arne uses MS Word to write his posts because it does have a good spell checker. MS Word puts lots of extra stuff in that is probably confusing the WA system which expect ASCII text. To get around this He copies and past to NotePad (I believe) but NotePad is not very ASCII compliant.

    Arne, can I suggest you try a writer's editor such as FocusWriter (just Google). It has a reasonable spell checker and handles ASCII, rtf and odf. Use rtf if you need formating but for AW use ASCII. For those who do not know ASCII is what is commonly known as a txt file.
  • 06 Dec 2011 17:07
    Quote
    Reply # 767156 on 766440
    Anonymous member
    I don't loose a single letter of the recent Arne posts ;o))







    I use Vista and Firefox 8.0
  • 06 Dec 2011 16:14
    Quote
    Reply # 767109 on 766440
    Deleted user
    Hei Arne,
    We are losing at least 6 or 7 letters from each line of your comments here as well.
    Why does Wild Apricot do this to your comments, and does not appear to do it to others?
    Can someone, maybe David or Paul Thompson throw some light on this??????
  • 06 Dec 2011 10:14
    Quote
    Reply # 766890 on 766440
    Anonymous member (Administrator)

    Stavanger Tuesday

    This is most interesting!

    Ti Gitus problems:

    Ti Gitu’s sails are very high aspect ratio and well outside my experience. Still from what I’ve seen on sheeting my friend’s schooner "Samson", it appears that problems soon get bigger with steeper and steeper sheeting angles. To get a better sheeting of the fore-sail (and maybe the main too), I think I would consider trying a rail-to-rail sheethorse and thus sheet the sails from the weather rail. See Samson's moderate AR schooner rig below:

    samson

    Paul Fay wrote : "2/ Also that the boom/ bottom panel needs to be cut short to stop the sheet catching there as well."

    Yes, I cut off 4-5% of the boom at the clew to avoid these problems on both Johanna and Broremann.

    Hong Kong parrels bending the battens:

    I too experienced this, early on my Malena, in 1994 (Batten 3 from top). Malena had a luff hauling parrel which worked on most of the luff. Later I found on Johanna that if I only use a luff hauling parrel on the yard and batten no 3, the sail below  it will be next to balanced with respect to weight. The Hong Kong parrels are then reduced to light trimming lines with no hard load on it. On both Johanna and Broremann I often see that the HK parrels are pretty slack, but they harden up a bit when I sail close-hauled. In fact, when Sebastian Hentschel (with plenty of offshore experience) made his new sail for Peregerine (front cover NL 57), he too just fitted this top luff hauling parrel and dropped the HK parrels altogether.About the fanned sail of Fantail I’m not so sure, since I’m not used to it, but I have to remind you that the Hong Kong parrels were seen on just this kind of sails – in Hong Kong.

    Preliminary conclusion:

    It could well be that I’m too optimistic about cambered panel sails for offshore use, but it could also be that the problems on Ti Gitu stems from other reasons; high AR, steep sheeting, under-engineered battens etc. The matter of scantlings has to be dealt with in that other thread about sheets and battens. There seems to be many thin battens out there...

    Cheers, Arne

    Last modified: 17 Dec 2011 10:54 | Anonymous member (Administrator)
  • 06 Dec 2011 03:51
    Quote
    Reply # 766729 on 766440
    Anonymous member
    Paul and Mo's comments were very interesting.  It's too early for me to comment adequately on Fantail's rig - I've sailed less than 200 miles with it - but I shall bear them in mind.  When - and if - I get to Northland, I will have a much more accurate idea of how my cambered sail works.  Thus far, however:

    Their comments back up what I feel about HK parrels, from fitting them to Fantail.  I think they put dreadful stresses on the rig.  They were bending my battens at rest, which, whatever engineering boffins might tell me, made me feel distinctly uneasy.

    From the little bit of sailing I've done with my cambered sail, I would say that it takes no more effort to handle than the flat sail - apart from needing a bit of muscle for the luff hauling parrel, which a lot of flat sails have anyway.

    I wonder if reefing too late on a beam reach is stressing their spars.  Junkies do seem strangely reluctant to reduce sail with a fair wind. - you may remember lots of stuff in early NLs about 'excessive weather helm', which in nearly all cases could be eliminated by reefing. 

    I would say that, although I haven't tried Fantail with a flat sail, she most certainly would not sail as well - or as fast - to windward, as she does with the cambered sail. 

    I think David's comment of 'horses for courses' is something we should all take on board.  And I would also like to hear from more people who have used cambered sails offshore: pros and cons.  Thank you, Paul and Mo, for getting this discussion on the practice rather than the theory of cambered sails under well.

    (By the way, this is in no way diminishing Arne's huge input into this sphere - it is the offshore experiences that are of interest here.)
    Last modified: 06 Dec 2011 03:55 | Anonymous member
  • 05 Dec 2011 20:56
    Quote
    Message # 766440
    Anonymous member
    I've received this email from Paul Fay, who has kindly agreed that I may publish it here:

    Hi David,

    I will write up our experience of converting to cambered panel sails as soon as I have time and post it on the website. For now suffice to say that Mo and I have been disappointed with them. They are more powerful but as you alluded too, getting this performance takes a lot more effort than just having a straight forward H & M rig. The loads in a cambered panel sail are TOTALLY different to a standard H & M rig. This has caused us bend the yards and battens, then after increasing the size of the yard and battens we have still bent the battens. Also, we do not believe our windward performance has improved much. Perhaps just a little in light winds. However we do think that if we could haul the sheet to windward this would improve. The Hong Kong parrels are an abomination which bend battens apart from needing setting up to start with.

    All in all we regret the complications that have been introduced for little gain in performance, especially on an ocean going yacht.

    The cambered panel sail may be good for those who continually want to experiment, but not for those who just want to sail, and after sailing through the Med and twice across the Atlantic I would recommend that Paul Thompson stick to basics.

    I do believe that the wing sail will be the way to go in the future but from what you have said it seems that it needs a lot more development.

    Ti Gitu is currently back in the UK spending the winter in Emsworth (Chichester Harbour). If  you happen to be in the area please call in, you will be most welcome.

    All the best,

    Paul and Mo. 

    and later:

    Since that, talking to Mo I have remembered another two problems which are:-

    1/ That with cambered panel sails the battens will not stack correctly which causes problems when raising the sail.

    2/ Also that the boom/ bottom panel needs to be cut short to stop the sheet catching there as well.

    Will write more soon,

    Paul and Mo 

    ... all of which reinforces my view that there are, and should be, different styles of junk rig for different boats, different users and different types of sailing. Anyone planning for a standard tradewind circumnavigation, with a majority of downwind sailing, might well be happiest staying with a flat sail. Anyone sailing in confined inshore waters should place a premium on windward efficiency, and should go for a well-cambered sail. And there are lots of other scenarios in between, all with their own optimum style of rig. One size doesn't fit all.
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