The Bermudan rig is crazy - Official!

  • 24 Oct 2014 21:50
    Reply # 3133219 on 3133193
    Deleted user
    David Tyler wrote: But consider this, Chris: the smallest satisfactory angle between mast and shroud is nine degrees, with up to fourteen degrees being more sensible, in terms of amount of tension/compression generated versus amount of mast support provided. Very few single masted vessels can achieve this angle, between a masthead shroud and the mast.
    David

    I believe those figures apply to a mast as a column in compression i.e. for bermudan-style rigging. I'm not sure they apply to a free-standing mast for which the shrouds are only intended to reduce 'whip'.

    I believe you are right about Lexia's foremast (and many others by Needlespar, including mine) being under-specified for strength and stiffness.

    Ilala's foremast was a staved wooden mast designed by Blondie Hasler. According to Mike Ellison, it was "very thick, but reasonably light in weight". He did become suspicious of it however when it 'bent like a fishing rod' on the way from Cobh back to Plymouth. We have of course to distinguish between strength and stiffness one one hand, and 'resilience'.  

    Ilala lost her foremast in a F2, with a heavy and confused swell, when it "... fell gently overboard to windward". This does not sound like a response to a lack of strength or stiffness, but more like the result of long-term weakening from continuous cycling of stresses. 

    I am of course playing devil's advocate here - I don't know what the answer is, which is why I raised the question.


  • 24 Oct 2014 20:56
    Reply # 3133195 on 3132858
    Gary King wrote:

    Sloppy seas is scary with unstayed masts for sure. Ashiki has been through a few of those already. Such movement needs fore-aft shrouds, chain plates are the wrong place!

    Looking at some of the alu mast failures, Lexia had a 3-1/2" dia. mast, I don't know about Ilala, but Lexia's was plainly too small. If Ashiki's came down, I'd replace with beefier, not stayed.

    The right response, Gary. There have been far too many professionally made masts with too small a diameter for adequate stiffness, let alone strength. 

    As I always say to people who question me on the soundness of unstayed masts: "If you design it right, build it right, and install it in the boat right, you will have a hard time making it fall over. Unlike a stayed mast".

  • 24 Oct 2014 20:51
    Reply # 3133193 on 3132806
    Chris Gallienne wrote:
    Graham Cox wrote:...I'll vote with the unstayed camp until my mast breaks, then I might switch sides!
    Me too - but if I was making an ocean crossing I might fit a couple of shrouds!
    But consider this, Chris: the smallest satisfactory angle between mast and shroud is nine degrees, with up to fourteen degrees being more sensible, in terms of amount of tension/compression generated versus amount of mast support provided. Very few single masted vessels can achieve this angle, between a masthead shroud and the mast.
  • 24 Oct 2014 20:40
    Reply # 3133191 on 3132938
    Deleted user
    S'OK Arne - I should not assume that everyone has gone through the same hassle as me learning that every place in China has had at least three different Europeanised names in history - in this case, Canton, Kwangtung (but not Kwantung, in northern China) and Guangdong (but not Guandong, ditto).

    I think Tom Colvin was always the 'go-to' man in the US for all things junk (probably still is). We're the minority over there. Not really surprising - how many other designers of Junks and Junk Rigs have over 20,000 miles offshore cruising in their products?


    Last modified: 24 Oct 2014 20:48 | Deleted user
  • 24 Oct 2014 15:08
    Reply # 3132938 on 3132803
    Anonymous member (Administrator)
    Chris Gallienne wrote:

    Arne

    I thought I was quite clear in my post that stayed masts were to be found around Guangdong (South China) and not in parts of China further north, and that Tom Colvin derived his experience only from this area.

    Chris


    Sorry Chris, my fault, I see now that Guangdong is the province surrounding Hong Kong. It is a bit surprising then that Tom Colvin’s view that a junk should have stayed masts almost has become a JR law in the US.

    Besides, when studying Karsten Petersen’s photos from Hong Kong, it appears that only the main mast has light shrouds, pointing a bit forward (varies between boats, it seems). I see no shrouds on the fore mast and mizzen on this one, at least.

    Arne

  • 24 Oct 2014 13:28
    Reply # 3132858 on 3121186
    Deleted user

    Sloppy seas is scary with unstayed masts for sure. Ashiki has been through a few of those already. Such movement needs fore-aft shrouds, chain plates are the wrong place!

    Looking at some of the alu mast failures, Lexia had a 3-1/2" dia. mast, I don't know about Ilala, but Lexia's was plainly too small. If Ashiki's came down, I'd replace with beefier, not stayed.

  • 24 Oct 2014 10:01
    Reply # 3132806 on 3132801
    Deleted user
    Graham Cox wrote:...I'll vote with the unstayed camp until my mast breaks, then I might switch sides!
    Me too - but if I was making an ocean crossing I might fit a couple of shrouds!
  • 24 Oct 2014 09:10
    Reply # 3132803 on 3121186
    Deleted user

    Arne

    I thought I was quite clear in my post that stayed masts were to be found around Guangdong (South China) and not in parts of China further north, and that Tom Colvin derived his experience only from this area.

    Chris

    Last modified: 24 Oct 2014 09:11 | Deleted user
  • 24 Oct 2014 09:03
    Reply # 3132802 on 3121186
    Anonymous member (Administrator)

    Chris,

    The use of stayed masts or not seems to depend on what region of the China coast we talk about. Remember that the Chinese coast is verylong.

    In Worchester’s ‘The junks & sampans of the Yanktze’ there are a number of rig drawings and also some photos. It appears that no staying is used on these boats and ships.

    However, if we go through Karsten Petersen’s photo collection, http://goo.gl/3ubCDp (skip page 2, it is empty..), showing junks from Hong Kong , mostly, almost all of these have stayed masts. On page 6 there is a junk from near Shanghai, and I cannot see any staying on that rig.

    Could it be that Tom Colvin mostly had been in contact with  ‘a stayed mast area’ of China or East Asia (..I don’t know much about Colvin...)? Many of his designs looks like hybrid of West and East. Nothing wrong with that if it works.

    Arne

    PS:
    I think aluminium masts can do fine without stays. One just has to put in a decent safety-factor when deciding for mast sections. After I started with aluminium masts, I have found that their max. diameter seems to end up around ¾ of that of a wooden mast.

     

    Last modified: 28 Oct 2014 12:29 | Anonymous member (Administrator)
  • 24 Oct 2014 08:59
    Reply # 3132801 on 3132515
    Chris Gallienne wrote:

    You are right, Annie, we are lucky to have unstayed masts, with all the advantages and economy entailed. I've been thinking about this quite a lot lately, since the passing of Tom Colvin.

    As most of us probably know, Tom always espoused 'lightly stayed' masts for his Chinese rigs, and believed this was the way the Chinese did it. Given that he had experience, as a sailor of a working sailing ship in south China in the first half of the last Century, of sailing working junks, he should know.

    It is fairly well-known that junks around Guangdong have used lightly stayed (shrouded?) rigs for at least a couple of centuries, possibly more. Many believe this was an adoption of Western techniques after European ships became regular visitors from the 17th Century onwards. The Chinese did not change the way they did things lightly, but knew enough to recognise and use a good thing when they saw one. It is equally possible that they developed this refinement independently, but given it's absence outside of areas influenced by European ships, probably improbable.

    Like Tom, those junks seemed to use fairly lightly stayed masts with little tension in them. Tom believed stays on the Chinese rig should not be used to support the mast, but simply to contain the 'whip effect' in a seaway, particularly with metal masts subject to fatigue failure. Given that both Ilala in the 1966 OSTAR, and Lexia in the 2013 OSTAR lost their masts in very little wind but while rolling around in a sloppy sea after a blow, there appears to be evidence to support this theory.

    If people don't like permanent shrouds either side of the mast, it is possible to have the same effect by running the halyard back to the cockpit via a block on the rail, with perhaps the spare halyard running to the opposite rail. 

    Any opinions?


    Edit: For an interesting insight into this issue see section 10.5 of Cutting the Dragon's Tail, by David and Lynda Chidell, who built and sailed one of Tom's designs, and stayed all three masts.

    I am currently writing a HOF article on Tom, so have been thinking and reading about this subject a lot.  I think there can be a case made for lightly stayed masts for the purposes of reducing whipping but I also think that, in smaller boats at least, is it also possible to use very stout unstayed masts, such as I have in Arion, and have a sufficient margin of safety.  Even so, the mast can whip unpleasantly in some conditions, usually in light winds and sloppy seas, exactly the sort of conditions that caused problems forIlala and Lexia.  The problem with stays, even lightly tensioned ones, is that they restrict the sail, especially on a broad reach and a run.  I love the way my sail can be squared right out without pressing on any rigging.  So I'll vote with the unstayed camp until my mast breaks, then I might switch sides!
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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