Chinese Gybes and how to prevent them

  • 26 Aug 2019 10:21
    Reply # 7849066 on 7848504

    I always ease the sheet way out once the wind is substantially aft of the beam, until the top sheeted batten is athwartships and the boom almost as far out.  The yard and upper, unsheeted, batten are usually beyond athwartships.  Being able to do this is one of the benefits of an unstayed rig.  I do this once the wind is more than 120 degrees off the bow, not just when running square.  Arion has a standard, three-span, six-part sheet and I would overhaul it, that is pull some of the sheet through from the top to let the boom out further, then ease more of the sheet, repeating the process as needed until both spars were well out.  Once I did this, I could sail up to 30 degrees by the lee without gybing, though I was leery if there was a good following sea and the boat was rolling.  Blue Moon currently has upper and lower sheets, so twist can be easily controlled, making squaring the sail out even easier. 

    Accidental gybes in rough weather remain a risk even with the sail squared well out, either from sudden wind shifts or being slewed by a passing wave, but the risk is minimalised.  If reefed, I tie a line around the reefed battens.  I have experimented with a fan-up preventer, and like the idea, but have not yet perfected it.  If you have full sail up off the wind and the sail is squared right out, without twist, I agree with Arne that a Chinese gybe is not going to be an issue.  Hopefully, you will only be running under full sail in light to moderate winds.  These days I reef early when off the wind.  The boat does not slow down but all the loads ease off.

    With the sail squared out like this, the wind is almost on the beam by the time you have completed an intentional gybe.  The sail still comes across with unnerving speed but is almost feathering once it is over.  It is important to sort out the deck so that the sheet does not snag as it sweeps across.  I basically do a flying gybe, leaving the sheet cleated at the squared-off position, but try to haul in a bit of slack in the sheet as the sail comes across, letting it run out again through gloved hands as the boom passes overhead.

    I feel there is no need to fear the Chinese gybe if you trim the sails correctly, and if you use some sort of restraint at the leach (either an FUP or a lashing) when reefed. 

  • 26 Aug 2019 10:16
    Reply # 7849065 on 7848504

    The video shows a straightforward broach, caused by the helmsman, and/or the fact that nobody seems to be trimming the kite (he releases the kite sheet and the boat recovers after losing crew overboard)  The broach happens before the main swings across... aided by gravity.  

  • 26 Aug 2019 10:06
    Reply # 7849064 on 7848504

    What a misleading article. What happens in the video is neither a Chinese gybe (the bottom of the sail gybes, but the top of the sail stays behind, resulting in an hourglass shape plastered against the mast, perhaps  with battens stuck behind shrouds or topping lifts), nor a death roll (the sail out square causing vortices to be shed off either side, resulting in rhythmic rolling). The helmsman looks behind him, loses the plot, sails by the lee, doesn't correct fast enough and crash gybes. That's all. The article is really about keeping the mainsail and spinnaker under control when racing fast downwind.

  • 26 Aug 2019 08:49
    Reply # 7848962 on 7848504
    Anonymous member (Administrator)

    Gybes in general and Chinese gybes in particular have been discussed here some years ago. It appears that it has many different explanations (The JRA glossary has their own one). What I have learnt is that a Chinese gybe starts on a sail with much twist in it. In that case the boom (not held down with a kicking strap/vang) will start the gybe and will then be lifted high up, and then the upper part follows on. I have seen this happen on a 60sqm gaff sail. It was quite a sight to see that massive boom flying up like that. Obviously such gybes (in particular with a long heavy gaff) puts enormous strain on the rig (and the leech of the sail).

    The best way of avoiding such calamities (apart from rigging with a squaresail) is to keep the twist to a minimum. I was out in Ingeborg yesterday, and we made a long gybe in a good breeze. Thanks to the almost zero twist in the sail, the whole sail from clew to peak started the gybe at the same moment, and swung over  -  fast. At the end, the sail met the headwind and the gybe stopped with slack sheets. My only worry during these gybes is that the sheet may catch something. Luckily, my new braced flagstaff (photo) appears to work well to prevent problems.

    I notice that Wikipedia says that the Chinese Gybe starts in the top of the sail  -  the opposite of what I have learnt...

    Arne

    PS: The gybe (of the mainsail) on that videoclip looks to me to be a straightforward, long gybe. It was the spinnaker which made things a bit interesting.


  • 26 Aug 2019 08:05
    Reply # 7848933 on 7848504
    Graeme wrote:

    I found this article in a Hong Kong boating magazine.

    I didn't think a Chinese gybe could actually happen to a junk, but the article was headed by this photo of a junk,

    so I read on, thinking it may be an idea for a fan-up preventer ....

    Turns out it was about the bermudan rig phenomenon, (and slightly different to what I thought was a Chinese gybe) and the article concluded "....postulated by Desoutter in Boat-Owner’s Practical Dictionary(1978), 53: ‘The term itself is an unwanted occidental jibe, for Chinese boats with their fully battened lug-sails are incapable of getting themselves into this specifically Bermudan predicament.’"

    phew! Thank goodness!

    Have a look at the "Chinese gybe" which the article refers to, at https://www.youtube.com/watch?time_continue=105&v=huKIDygg264

    and be glad you have a junk rig!


    (The full article is at http://www.asiaatsea.com/chinese-gybes-prevent/  )


    Well, don't get too complacent. I have proved on 'Footprints' that it is possible to do some very spectacular gybes with a junk rig. This is probably helped by the great big low aspect 53 square meter sail on Footprints and the way I keep on pushing the performance envelope, but I learned very early on that the junk rig gentle gybe is a bit of a myth. I think that if it were not for the bimini frame I would have lost my head on at least one occasion. Every type of rig has its vices and needs to be treated with respect.

    Nice looking junk in the photo!

    Last modified: 26 Aug 2019 08:07 | Anonymous member
  • 25 Aug 2019 23:37
    Message # 7848504

    I found this article in a Hong Kong boating magazine.

    I didn't think a Chinese gybe could actually happen to a junk, but the article was headed by this photo of a junk,

    so I read on, thinking it may be an idea for a fan-up preventer ....

    Turns out it was about the bermudan rig phenomenon, (and slightly different to what I thought was a Chinese gybe) and the article concluded "....postulated by Desoutter in Boat-Owner’s Practical Dictionary(1978), 53: ‘The term itself is an unwanted occidental jibe, for Chinese boats with their fully battened lug-sails are incapable of getting themselves into this specifically Bermudan predicament.’"

    phew! Thank goodness!

    Have a look at the "Chinese gybe" which the article refers to, at https://www.youtube.com/watch?time_continue=105&v=huKIDygg264

    and be glad you have a junk rig!


    (The full article is at http://www.asiaatsea.com/chinese-gybes-prevent/  )


    Last modified: 25 Aug 2019 23:38 | Anonymous member
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