[Public-List] Mast Sheave Bolt

Wed Mar 11 08:36:20 PDT 2020

works for me...

On Wed, Mar 11, 2020 at 9:15 AM Gordon Laco via Public-List <
public-list at lists.alberg30.org> wrote:

> Morning Gang,
>
> 3% stretch on 35 feet is actually 0.03 feet…less than an inch which is not
> much, and one can load up the halyard using a winch to negate that…
>
> Most marine quality rope is prestretched and heat treated to lock it these
> days…
>
> Stretch in rope is an interesting subject.  My professional work
> outfitting classic yachts and sailing ships causes me to look at
> traditional rigging a lot, and that has led to some interesting revelations.
>
> The first one, which seems heretical, is that good quality hemp rope (yes,
> hemp) stretches LESS than polyester rope when made in the same diameter and
> type (ie braided or twisted)  It is also just as strong…  we have had it
> tested and the results are uniformly confirming of what I just wrote.  Yes,
> that was startling.
>
> Good quality hemp rope feels soft, like human hair… and unlike manila or
> sisal, is unaffected by humidity with regard to dimensional stability.
> Manila is ’twiggy’ and shrinks dramatically when wet… not good if one is
> using it in shroud lanyards etc… and it swells in diameter, not good if one
> is hoping it will run through blocks.
>
> So why don’t people use it?  There are a number of reasons…
>
> First, being natural fibre, its longevity at rated performance is
> completely unpredictable.  Yes, when it’s new, and well made, it is better,
> but after a season in service it might still be good, but nobody can tell.
>  In modern work, we cannot guarantee performance statistics for natural
> fibre rope after it’s been in service, only when it is new.  Synthetic rope
> can be counted on to be predictable in performance, even when older…
>
> Second, it can rot in a variety of ways.  Up to WW2, it was common for
> yachts to tar their rope with pine tar… it looks and feels like maple syrup
> and when rope is impregnated with it, preservation is quite good… but it’s
> messy and gets on sails and clothing even when dry.
>
> Third, when synthetics came along, there was of course rejoicing because
> it appeared that people were going to be spared the cost and toil of
> replacing their rigging constantly, but there was also some evil on the
> part of synthetic manufacturers.  The industry that grew and processed hemp
> was literally demonized to the point where it doesn’t exist in North
> America any longer.  The good quality hemp rope we supply now comes from
> Holland.   And that is funny because we have farms near where I am writing
> which grow hemp, but they ship their produce to Europe for processing
> because we don’t do that on this side of the Atlantic anymore.
>
> There are two kinds of stretch in rope… what I call ‘mechanical
> elongation’, and ‘fibre elongation’.  The later is the actual elongation of
> the stuff the rope is made of… the former is how the matrix of the rope
> adjusts itself under load, and becomes longer.  Twisted rope has greater
> mechanical elongation than double braided rope.
>
> A word on knots vs splices.   All published data will confirm that a
> splice retains a higher percentage of a rope’s strength than a knot.  One
> day a number of years ago when I was teaching rigging at Georgian College,
> I had just covered that in a lecture, and let my students out for a break
> before resuming.   Outside I heard cheering and engines revving… I looked
> out at the gravel parking lot and saw my students apparently rioting around
> two pick up trucks tethered by their towing hitches… one was dragging the
> other all over the place… finally the line connecting them broke.
>
> My students had taken a piece of 1/2” nylon three strand… spliced an eye
> in one end and tied a bowline in the other, then tried to break it.  Two
> results came of that experiment.  First, the Ford dragged the GM pick up
> all over the place.  Second, the line broke in the middle!  That is not
> supposed to happen…haha
>
> So there’s along and uncalled for lecture on rope…
>
> Gordon Laco
> www.gordonlaco.com
>
>
>
>
> > On Mar 10, 2020, at 11:38 PM, Don Campbell via Public-List <
> public-list at lists.alberg30.org> wrote:
> >
> > So far, no one has mentioned that rope halyards are prone to stretch and
> so if you do use rope halyards, and are not prepared to spend the bundle
> for staset or other non-stretch line, you have the stretch on 35 feet if
> you cleat on the mast or about 50 feet if you lead the halyard back to the
> cockpit. Even a 3% stretch factor on relatively low stretch line will give
> at least a foot on 35 feet,  double or triple that on more ordinary line.
> Just make sure you check this factor regardless of where the halyards are
> if you want to maintain mainsail shape. Wire does not stretch much at all
> and the rope tail is very short if the wire is measured correctly.
> > Don
> >
> > -----Original Message----- From: Gordon Laco via Public-List
> > Sent: Tuesday, March 10, 2020 2:16 PM
> > To: Alberg 30 Public List -- open to all
> > Cc: Gordon Laco ; George Dinwiddie ; Daniel Swords
> > Subject: Re: [Public-List] Mast Sheave Bolt
> >
> > By the way Daniel... did you see that the movie I was working on when I
> visited you is being released in June?
> >
> > G
> >
> > Sent from my iPhone
> >
> >> On Mar 10, 2020, at 1:19 PM, Daniel Swords via Public-List <
> public-list at lists.alberg30.org> wrote:
> >>
> >>
> >> BUT - as Gordon pointed out there are some definite potential failure
> modes here and I would not recommend this system for hoisting a bosun’s
> chair. This system works for me and has for many years without the use of
> the mast sheave and without internal halyards but there are probably better
> and safer ways to attach blocks to the masthead.
> >>
> >>
> >> Sent from Yahoo Mail for iPhone
> >>
> >>
> >> On Tuesday, March 10, 2020, 11:27 AM, George Dinwiddie <
> gdinwiddie at alberg30.org> wrote:
> >>
> >> Daniel,
> >>
> >> If you send the photo to me, I'll be glad to post it on the website.
> >> Include a description and I'll add that, too.
> >>
> >>  - George
> >>
> >>> On 3/10/20 11:18 AM, Daniel Swords via Public-List wrote:
> >>> I just happen to have a photo!  Who can I post it to?  Can I mention
> “Fa—-b—“ on this site or would that be rude?
> >>>
> >>>
> >>> Sent from Yahoo Mail for iPhone
> >>>
> >>>
> >>> On Tuesday, March 10, 2020, 10:15 AM, Gordon Laco <mainstay at csolve.net>
> wrote:
> >>>
> >>> That’s exactly how our main halyard is rigged.  Nothing is internal…
> just a traditional masthead sheave that carries the halyard from the
> forward face of the stick to the after…
> >>> Gordon Lacowww.gordonlaco.com
> >>>
> >>>
> >>>
> >>>
> >>> On Mar 10, 2020, at 11:13 AM, Jonathan Bresler <262alberg30 at gmail.com>
> wrote:
> >>> All halyards external?
> >>> The masthead on Constance has two pins abaft the mast: one is used for
> the backstay, and the other for the main topping lift.At least that is my
> recollection.  The main halyard line is external but for the small part
> passing over the sheave in the mast. Where do you hang a block for an
> external main halyard?   Photos?
> >>> Jonathan
> >>>
> >>> On Tue, Mar 10, 2020 at 11:09 AM Gordon Laco via Public-List <
> public-list at lists.alberg30.org> wrote:
> >>>
> >>> I have all my halyards external in Surprise’s rig, as she was when she
> was built.
> >>>
> >>> We still win races, and I never worry about what’s going on inside the
> mast that I cannot see.
> >>>
> >>> Gordon Laco
> >>> www.gordonlaco.com
> >>>
> >>>
> >>>
> >>>
> >>>> On Mar 10, 2020, at 10:59 AM, Daniel Swords via Public-List <
> public-list at lists.alberg30.org> wrote:
> >>>>
> >>>> I have abandoned my mast sheave and internal halyards and replaced
> them with simpler blocks and external halyards. You would have to provide
> me with wind tunnel data to convince me that at 6.5 or even 7 knots of
> speed the
> >
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