[Rhodes22-list] Mainsail slugs (was Mast Crane) (was Lou Moore)

[Rik Sandberg]

Steve,

Thanks for that. It seemed kind of odd to me that the slug on the headboard 
should be all worn out when the rest look good.

How far from the top is your upper-most slug then?

Rik


At 03:52 PM 3/19/2004, you wrote:
>Rik
>Well, this is my reason, 3 of us got slugs on our
>mainsail a little over three years ago.  2 of us (me
>included) had Rooke Sail put them on & they didn't
>have one on the headboard.  The other one send off to
>a sail loft for a cheaper price & his had one on the
>headboard.  Ours worked fine; his - dammed thing
>wouldn't go up the mast.  All three of us tried
>everything we could think of to get it to work; then I
>notice that we didn't have the slug on our 2. We cut
>it off his and it worked.  I know, its not the
>greatest reason in the world, but it work & I sure was
>tried of trying to figure out what was wrong.
>Steve
>
>
>
>--- Rik Sandberg <sanderico at earthlink.net> wrote:
> > Steve,
> >
> > Hmmm....don't need a slug on the headboard.....I too
> > had (key word had) a
> > slug on the headboard of the mainsail on my Flicka.
> > It wore out and broke
> > when we were down at Kentucky Lake last fall. the
> > other slugs seem to be
> > fine. I was wondering how to go about replacing it,
> > but if this is right, I
> > shouldn't have to.
> >
> > Can you explain why a slug isn't needed on the
> > headboard?? It seems there's
> > a lot of new stuff to learn when you go from a IMF
> > main to a standard main :-)
> >
> > Rik
> >
> >
> > At 01:49 PM 3/19/2004, you wrote:
> > >Lloyd
> > >The slug in the headboard was the problem.  Didn't
> > >need one there.
> > >Steve
> > >
> > >
> > >--- Lloyd Crowther <lcrowther at cox.net> wrote:
> > > > Roger,
> > > >
> > > > Thanks for the prompt reply.  My problem was
> > more
> > > > that I couldn't get my
> > > > Main all the way up rather than I couldn't get
> > it
> > > > down.  Before I had the
> > > > 7/16" plastic, cylindrical slugs sewn onto
> > grommets
> > > > the sail maker later
> > > > placed aft of the bolt rope along the mainsail's
> > > > luff, I tied a slug to my
> > > > halyard, tied a string to the lower part of the
> > slot
> > > > on the slug to pull the
> > > > slug back down, and hoisted it up, no problem.
> > I
> > > > took the sail to Quantum
> > > > Sails Loft in Annapolis and asked them to put
> > the
> > > > slugs on.  When I tried to
> > > > raise the sail, the topmost slug would bind
> > about
> > > > 3/4 t0 7/8 of the way to
> > > > the masthead no matter what I did, lubrication
> > or
> > > > any thing else. I never
> > > > had any problem getting the sail back down
> > because I
> > > > did all this in my
> > > > slip.  I did take the precaution of looping a
> > light
> > > > line through the bottoms
> > > > of the slug slots so if they twisted I could
> > pull on
> > > > the line to re-tension
> > > > any slug that twisted.
> > > >
> > > > I just went down to the cellar and measured the
> > > > spacing of the grommets they
> > > > put along the luff (I cut the slugs off when I
> > > > abandoned the whole exercise
> > > > last spring) and found they were 18" on centers.
> >  So
> > > > I guess you have solved
> > > > some if not all of my problem although I doubt
> > that
> > > > I pay all that money
> > > > again to prove you right.
> > > >
> > > >   My thought was that as the sail got nearer the
> > > > pulley in the mast. the
> > > > halyard tended to pull the headboard, with its
> > > > sewed-on slug, in towards the
> > > > mast, relieving the pressure on that slug and
> > > > allowing it to twist and bind.
> > > > In any event, thank you again for your rapid and
> > > > responsive reply, your
> > > > knowledge continues to amaze me.
> > > >
> > > > Lloyd
> > > >
> > > > ----- Original Message -----
> > > > From: "Roger Pihlaja" <cen09402 at centurytel.net>
> > > > To: "The Rhodes 22 mail list"
> > > > <rhodes22-list at rhodes22.org>
> > > > Sent: Friday, March 19, 2004 5:45 AM
> > > > Subject: Re: [Rhodes22-list] Mast Crane (was Lou
> > > > Moore)
> > > >
> > > >
> > > > > Lloyd,
> > > > >
> > > > > I used 7/16" dia. cylindrical plastic sail
> > slugs
> > > > on the luff and a 7/16"
> > > > > dia. bolt rope on the foot.  Note: There are
> > two
> > > > styles of sail slugs in
> > > > > common use, T-shaped & cylindrical shaped.
> > Each
> > > > style is designed to be
> > > > > used with the cooresponding slot shape on a
> > mast
> > > > and they are not
> > > > > interchangable.  On Dynamic Equilibrium, the
> > > > cylindrical style of sail
> > > > slug
> > > > > matched the configuration of the extruded slot
> > on
> > > > the mast.  If a bolt
> > > > rope
> > > > > works well in your mast slot; then, I would
> > expect
> > > > the cylindrical style
> > > > > sail slugs are the correct ones for your mast
> > as
> > > > well.  However, I would
> > > > > check to be certain.  7/16" dia cylindrical
> > sail
> > > > slugs are the same size
> > > > as
> > > > > came on the OEM standard sail.
> > > > >
> > > > > Here's a couple of tips you might try on the
> > mast
> > > > groove:
> > > > >
> > > > > Take a rag & moisten it with a good silicone
> > > > lubricant like Dow Corning
> > > > > Slipicone.  Run the oily rag up & down the
> > length
> > > > of the slot.  The
> > > > > Slipicone will remove any accumulated crud
> > that's
> > > > built up in the slot,
> > > > plus
> > > > > it will also leave behind a silicone wax
> > finish
> > > > that is much more slippery
> > > > > than the bare anodized aluminum finish.  Do
> > the
> > > > same thing with the
> > > > plastic
> > > > > slugs on the mainsail.  NOTE: Dispose of this
> > oily
> > > > rag by immediately
> > > > > burning it OR soak it in water, put it in a
> > > > plastic bag, & put it out with
> > > > > this week's trash.  NEVER just leave it
> > sitting
> > > > around or it may
> > > > > spontaneously ignite & start a fire.  I
> > usually do
> > > > this maintenance on the
> > > > > mast slot at the beginning of the sailing
> > season.
> > > > >
> > > > > While you are wiping down the slot, take
> > special
> > > > note of the location on
> > > > the
> > > > > mast if you feel any rough spots, dents, or
> > burrs.
> > > >  Go back and carefully
> > > > > inspect those spots.  A dent or burr on the
> > inside
> > > > surface of the slot can
> > > > > cause the bolt rope or sail slides to hang up.
> >  A
> > > > minor dent or burr can
> > > > be
> > > > > smoothed with 400 grit emery cloth.  A rough
> > spot
> > > > is quite often a
> > > > build-up
> > > > > of something like tree sap or bird droppings,
> > > > which can be removed with a
> > > > > product like Formula 409.  One year, I even
> > > > discovered a mud dauber wasp
> > > > > nest in the slot!  I was relieved to find the
> > wasp
> > > > nest because something
> > > > > was absolutely jamming the mainsail at that
> > point
> > > > on the mast.  I was
> > > > afraid
> > > > > it was something really serious.
> > > > >
> > > > > While you are wiping down the sail slugs, take
> > > > note if any of them are
> > > > > damaged or have rough spots on them.  Repair
> > or
> > > > replace as required.
> > > > >
> > > > > After cleaning out the mast slot, take one of
> > your
> > > > sail slugs & run it up
> > > > &
> > > > > down the length of the slot on the mast.  It
> > > > should move freely with no
> > > > > binding anywhere.  It's possible the gap width
> > on
> > > > the slot on your mast
> > > > has
> > > > > a "tight spot" wherein the gap width is off
> > spec
> > > > too narrow.  This
> > > > condition
> > > > > can be repaired by forcing a wooden wedge into
> > the
> > > > slot in the narrow
> > > > areas
> > > > > to widen the gap.  Depending upon the length
> > of
> > > > the narrow slot region,
> > > > you
> > > > > might have to custom make this wedge to fit
> > your
> > > > situation.
> > > > >
> > > > > It's also possible that the sail slugs on the
> > sail
> > > > you tried were spaced
> > > > too
> > > > > far apart.  The sail slugs need to be spaced
> > no
> > > > more than about 12" apart
> > > > on
> > > > > center, or they tend to get cocked and bind up
> > in
> > > > the slot.  Also, the
> > > > tiny
> > > > > shackles that attach the sail slugs to the
> > luff on
> > > > the mainsail must be
> > > > the
> > > > > proper size.  If they are too short, the luff
> > will
> > > > bind on the trailing
> > > > edge
> > > > > of the slot.  If they are too long, they may
> > allow
> > > > the sail slug to become
> > > > > cocked in the slot & bind up.
> > > > >
> > > > > Finally, I'm sure you already know this; but,
> > I'll
> > > > just mention it for the
> > > > > sake of completeness.  No mainsail will drop
> > down
> > > > the mast easily if the
> > > > > sail is under load.  This means the boat must
> > be
> > > > head to the wind, the
> > > > boom
> > > > > must be centered, with the boom topping lift
> > > > supporting the weight of the
> > > > > boom.
> > > > >
> > > > > If none of this works for you Lyoyd; then, I'm
> > at
> > > > a loss to explain why
> > > > your
> > > > > mainsail won't fall down the mast when the
> > halyard
> > > > is released.
> > > > >
> > > > > Roger Pihlaja
> > > > > S/V Dynamic Equilibrium
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "Lloyd Crowther" <lcrowther at cox.net>
> > > > > To: "The Rhodes 22 mail list"
> > > > <rhodes22-list at rhodes22.org>
> > > > > Sent: Friday, March 19, 2004 1:27 AM
> > > > > Subject: Re: [Rhodes22-list] Mast Crane (was
> > Lou
> > > > Moore)
> > > > >
> > > > >
> > > > > > Roger,
> > > > > >
> > > > > > What size sail slugs do you use?  I tried
> > 7/16"
> > > > plastic sail slugs and
> > > > > > couldn't even get the sail all the way up
> > > > without it binding.  Don't
> > > > have
> > > > > > any trouble with  raising it with the bolt
> > rope
> > > > but it is a bear to
> > > > furl
> > > > > if
> > > > > > your a single-hander.
> > > > > >
> > > > > > Lloyd
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > From: "Roger Pihlaja"
> > <cen09402 at centurytel.net>
> > > > > > To: "The Rhodes 22 mail list"
> > > > <rhodes22-list at rhodes22.org>
> > > > > > Sent: Thursday, March 18, 2004 11:35 PM
> > > > > > Subject: Re: [Rhodes22-list] Mast Crane (was
> > Lou
> > > > Moore)
> > > > > >
> > > > > >
> > > > > > > Peter,
> > > > > > >
> > > > > > > I modified the standard masthead with some
> > > > aluminum bar stock & a MIG
> > > > > > > welder.
> > > > > > >
> > > > > > > Look on the FAQ page for the tension
> > settings.
> > > > > > >
> > > > > > > The way to measure maximum chord inches is
> > to
> > > > first load up the rig
> > > > with
> > > > > > the
> > > > > > > backstays.  Then, run the main halyard
> > down to
> > > > the base of the mast &
> > > > > tie
> > > > > > it
> > > > > > > off taut against the slot on the aft face.
> > > > Then, using a bosun's
> > > > chair
> > > > > or
> > > > > > a
> > > > > > > step ladder to get up high enough on the
> > mast,
> > > > measure the maximum
> > > > > > > chord-inches from the halyard to the slot
> > on
> > > > the mast.
> > > > > > >
> > > > > > > Note: If all you want to do is eliminate
> > the
> > > > headstay sag, the
> > > > standard
> > > > > > > backstay adjuster with the standard
> > masthead
> > > > geometry will do that.
> > > > The
> > > > > > > only real reason for the crane is to
> > create
> > > > clearance between the
> > > > > > backstays
> > > > > > > and the big roach of a fully battened
> > > > mainsail.  You also need to be a
> > > > > > > little conservative re the amount of roach
> > in
> > > > the mainsail.  Designing
> > > > > in
> > > > > > > too much roach will disrupt the balance of
> > the
> > > > sail plan by shifting
> > > > the
> > > > > > > center of effort (CE) aft, thus causing an
> > > > excessive amount of weather
> > > > > > helm.
> > > > > > > Some of this weather helm can be dialed
> > back
> > > > out by adjusting the
> > > > static
> > > > > > > tilt of the mast such that the mast leans
> > > > forward slightly, thus
> > > > moving
> > > > > > the
> > > > > > > CE of the rig forward.  The static tilt of
> > the
> > > > mast is adjusted with
> > > > the
> > > > > > > turnbuckle on the forestay or by
> > shortening
> > > > the forestay cable.
> > > > > > >
> > > > > > > After having installed both a high tech
> > > > composite genoa on a Harken
> > > > > roller
> > > > > > > furler & a fully battened mainsail, I'd
> > say
> > > > the genoa returns the
> > > > > biggest
> > > > > > > performance bang for the buck.  But, the
> > fully
> > > > battened mainsail looks
> > > > > > > totally cool when hoisted & the sail shape
> > is
> > > > much easier to adjust to
> > > > > > > exactly what you want for the prevailing
> > > > conditions & point of sail.
> > > > > > >
> > > > > > > You will have a choice between sail slugs
> > and
> > > > a bolt rope on the luff.
> > > > > I
> > > > > > > choose sail slugs & my mainsail almost
> > falls
> > > > down the mast when the
> > > > > > halyard
> > > > > > > is released.  Reefing it under load
> > sometimes
> > > > requires the sail be
> > > > > hauled
> > > > > > > down; but, that was true with the
> > partially
> > > > battened mainsail as well.
> > > > > > You
> > > > > > > will have a choice between loose footed &
> > > > footed using a bolt rope.  I
> > > > > > > choose a bolt rope on the foot, mainly
> > because
> > > > that's what the
> > > > standard
> > > > > > > mainsail had.  I would order the optional
> > > > zippered shelf which will
> > > > > allow
> > > > > > > you to increase the fullness of the lower
> > 1/3
> > > > of the mainsail shape
> > > > for
> > > > > > > light air.  You zip up the shelf to
> > flatten
> > > > the mainsail shape for
> > > > heavy
> > > > > > > air.  After you've paid the big bucks for
> > this
> > > > fully battened
> > > > mainsail,
> > > > > > > definitely get a leech line & cleat.  The
> > > > primary function of the
> > > > leech
> > > > > > line
> > > > > > > is to stop the trailing edge of the sail
> > from
> > > > fluttering as the air
> > > > foil
> > > > > > > sheds its trailing vortices.  This
> > fluttering
> > > > subjects the sailcloth &
> > > > > > > stitching in the leech to a lot of high
> > > > frequency wear cycles, which
> > > > can
> > > > > > > result in premature fatigue failure of the
> > > > material.  You tighten the
> > > > > > leech
> > > > > > > line just enough to stop the fluttering.
> > > > Thus, the leech line extends
> > > > > the
> > > > > > > life of your expensive new sail & is well
> > > > worth the money up front to
> > > > > have
> > > > > > > it installed.  You will have to specify
> > the
> > > > number of reef points in
> > > > > your
> > > > > > > new mainsail.  I originally ordered just 1
> > set
> > > > & later had a sailmaker
> > > > > > > retrofit a 2nd set.  The next time around,
> > I
> > > > will order two sets of
> > > > reef
> > > > > > > points.  My 1st reef point reduces the
> > > > mainsail area by 1/3 and the
> > > > > second
> > > > > > > reef point by 2/3 relative to the full
> > > > mainsail area.
> > > > > > >
> > > > > > > Finally, this new fully battened mainsail
> > will
> > > > be substantially
> > > > bulkier
> > > > > > when
> > > > > > > furled on the boom vs. the standard
> > mainsail.
> > > > The chances are, your
> > > > > > current
> > > > > > > mainsail cover will no longer fit.  I
> > modified
> > > > my old mainsail cover
> > > > to
> > > > > > fit
> > > > > > > the new sail.
> > > > > > >
> > > > > > > Roger Pihlaja
> > > > > > > S/V Dynamic Equilibrium
> > > > > > >
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > > From: "Peter Thorn" <pthorn at nc.rr.com>
> > > > > > > To: "The Rhodes 22 mail list"
> > > > <rhodes22-list at rhodes22.org>
> > > > > > > Sent: Thursday, March 18, 2004 5:21 PM
> > > > > > > Subject: Re: [Rhodes22-list] Mast Crane
> > (was
> > > > Lou Moore)
> > > > > > >
> > > > > > >
> > > > > > > > Roger,
> > > > > > > >
> > > > > > > > I certainly will try it.  It sounds
> > great!
> > > > > > > >
> > > > > > > > Where did you acquire your 12" mast
> > crane?
> > > > Do you recall Loos
> > > > > settings
> > > > > > > for
> > > > > > > > forwards, uppers and aft shrouds?
> > > > > > > >
> > > > > > > > With only 4 cord/inches upper mast bend,
> > my
> > > > guess is the greatest
> > > > > > benefit
> > > > > > > is
> > > > > > > > headsail luff sag adjustment.   If you
> > can
> > > > obtain enough tension to
> > > > > keep
> > > > > > a
> > > > > > > > 150 Genoa close to zero cord/inches in a
> > > > blow, you must be putting
> > > > > > > 400-500
> > > > > > > > pounds on the headstay.   R22
> > construction
> > > > looks like it would take
> > > > > > that.
> > > > > > > > Stan builds 'em beefy.
> > > > > > > >
> > > > > > > > Thinking out loud - 1) built the rig
> > first,
> > > > 2) measure/verify the
> > > > > > > > "reasonable mast bend" above the
> > spreaders,
> > > > 3) send numbers to
> > > > > > sailmaker.
> > > > > > > > Can you think of anything else?
> > > > > > > >
> > > > > > > > Best,
> > > > > > > >
> > > > > > > > PT
> > > > > > > >
> > > > > > > >
> > > > > > > > > Peter,
> > > > > > > > >
> > > > > > > > > With the forestay cable buried inside
> > of
> > > > the roller furling foil &
> > > > > > > > > impossible to get at with a Loo's
> > Tension
> > > > gage, I've never
> > > > measured
> > > > > > the
> > > > > > > > > forestay tension.  I have some
> > calculated
> > > > theoretical values; but,
> > > > > > they
> > > > > > > > > would only apply to my particular boat
> > &
> > > > masthead geometry &
> > > > > wouldn't
> > > > > > be
> > > > > > > > of
> > > > > > > > > much use to anyone else.  When you
> > refer
> > > > to "chord-inches, I
> > > > presume
> > > > > > you
> > > > > > > > > mean the maximum perpendicular
> > distance
> > > > from the chord to the
> > > > radius
> > > > > > of
> > > > > > > > > curvature?  Assuming my definition of
> > > > chord-inch agrees with
> > > > yours,
> > > > > > with
> > > > > > > > the
> > > > > > > > > range of adjustments on Dynamic
> > > > Equilibrium as currently
> > > > configured,
> > > > > > > over
> > > > > > > > > the 333-5/8 inch length of the
> > forestay, I
> > > > can adjust the
> > > > chord-inch
> > > > > > > value
> > > > > > > > > from nearly 0 to about 6 inches.  The
> > > > aluminum extrusions on the
> > > > > > > headsail
> > > > > > > > > foils won't sag too much more than
> > that
> > > > without causing bearing
> > > > and
> > > > > > > > furling
> > > > > > > > > problems.
> > > > > > > > >
> > > > > > > > > On my current fully battened mainsail,
> > I
> > > > went fairly conservative
> > > > on
> > > > > > the
> > > > > > > > > amount of mast bend the mainsail can
> > > > respond to.  It is currently
> > > > > cut
> > > > > > to
> > > > > > > > > respond to only about 2 chord-inches,
> > > > mostly above the spreaders.
> > > > > The
> > > > > > > > mast
> > > > > > > > > curvature actually trails off
> > > > asymptotically to 0 below the
> > > > > spreaders
> > > > > > > > > because of stretch in the lower sides
> > > > stays and the differential
> > > > > > > fore/aft
> > > > > > > > > static load I put on the lower side
> > stays.
> > > >  The forward lower side
> > > > > > stays
> > > > > > > > are
> > > > > > > > > adjusted tighter than the rear lower
> > side
> > > > stays to facilitate mast
> > > > > > > > bending.
> > > > > > > > > I think the amount of mast bend could
> > be
> > > > increased to about 4
> > > > > > > cord-inches
> > > > > > > > > without any trouble.  When the time
> > comes
> > > > to replace this
> > > > mainsail,
> > > > > > > that's
> > > > > > > > > the spec I plan to ask for.  With the
> > > > current aluminum mast
> > > > > extrusion,
> > > > > > > > > trying for more bend than about 4
> > > > cord-inches is asking for
> > > > trouble
> > > > > in
> > > > > > > my
> > > > > > > > > engineering judgement.  The aluminum
> > > > extrusion might experience
> > > > > > fatigue
> > > > > > > > > failure (especially in a salt water
> > > > environment) and the loads on
> > > > > the
> > > > > > > > > forestay & backstays would start to
> > get a
> > > > little high for the hull
> > > > > > > > structure
> > > > > > > > > and chain plates.
> > > > > > > > >
> > > > > > > > > As you probably already know, you bend
> > the
> > > > mast to straighten the
> > > > > > > > forestay,
> > > > > > > > > thereby reducing headstay sag plus
> > flatten
> > > > the mainsail shape.
> > > > Both
> > > > > > > > actions
> > > > > > > > > depower the rig for heavy air.  Yes,
> > > > depowering the rig with the
> > > > > > > backstay
> > > > > > > > > adjuster is much faster than any other
> > > > method because it takes
> > > > care
> > > > > of
> > > > > > > > both
> > > > > > > > > sails at the same time.  I have my
> > > > backstay adjuster setup with a
> > > > > > Harken
> > > > > > > > 144
> > > > > > > > > swivel cam base with 150 cam-matic
> > cleat,
> > > > 082 single bullet block,
> > > > &
> > > > > > 071
> > > > > > > > > stand-up spring mounted on the aft
> > > > starboard gunnel.  The
> > > > swiveling
> > > > > > arm
> > > > > > > > cam
> > > > > > > > > base & cam-matic cleat on the end of
> > the
> > > > arm allows me to reach
> > > > the
> > > > > > > > backstay
> > > > > > > > > adjuster from virtually any helm
> > position.
> > > >  The backstay adjuster
> > > > > line
> > > > > > > is
> > > > > > > > > marked with calibration marks for
> > quick,
> > > > reproducible tension
> > > > > > > adjustments.
> > > > > > > > > I used the big Harken 144 swivel cam
> > base
> > > > because this unit is
> > > > > mounted
> > > > > > > > right
> > > > > > > > > by where people come aboard over the
> > > > transom from the boarding
> > > > > ladder.
> > > > > > > > The
> > > > > > > > > 144 is sufficiently stout that you can
> > > > stand on the swiveling arm
> > > > > > > without
> > > > > > > > > damaging it.  I've been sailing with
> > this
> > > > backstay adjuster setup
> > > > > > since
> > > > > > > > > 1988.  It's been absolutely
> > bulletproof so
> > > > far.
> > > > > > > > >
> > > > > > > > > Try it - You'll like it a whole bunch!
> > > > > > > > >
> > > > > > > > > Roger Pihlaja
> > > > > > > > > S/V Dynamic Equilibrium
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > ----- Original Message -----
> > > > > > > > > From: "Peter Thorn" <pthorn at nc.rr.com>
> > > > > > > > > To: "The Rhodes 22 mail list"
> > > > <rhodes22-list at rhodes22.org>
> > > > > > > > > Sent: Thursday, March 18, 2004 10:44
> > AM
> > > > > > > > > Subject: Re: [Rhodes22-list] Mast
> > Crane
> > > > (was Lou Moore)
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > > Roger,
> > > > > > > > > >
> > > > > > > > > > Thanks for the detailed explanation.
> >  I
> > > > am the child of an ME,
> > > > but
> > > > > > not
> > > > > > > > one
> > > > > > > > > > myself.  All my engineering is pants
> > > > seat.  I'll add "eccentric
> > > > > > > loading"
> > > > > > > > > to
> > > > > > > > > > my sailing jargon vocabulary.
> > > > > > > > > >
> > > > > > > > > > So, how much tension can you add to
> > your
> > > > forestay by adjusting
> > > > > your
> > > > > > > > > > backstay?  Can the 12" crane
> > actually
> > > > put more tension on
> > > > forestay
> > > > > > > than
> > > > > > > > > std
> > > > > > > > > > crane can?  We all know a light beam
> > > > straight entry points much
> > > > > > > better.
> > > > > > > > > >
> > > > > > > > > > And, will your Harken furler track
> > allow
> > > > the forestay to sag and
> > > > > > power
> > > > > > > > up
> > > > > > > > > > (for light air)?
> > > > > > > > > >
> > > > > > > > > > For any boat with sail reduction
> > > > capacity, mast bending might be
> > > > a
> > > > > > bit
> > > > > > > > > > unnecessary - but  non-the-less
> > > > interesting.  After all, one can
> > > > > > bend
> > > > > > > > the
> > > > > > > > > > mast probably quicker than any other
> > > > de-powering technique.
> > > > > During
> > > > > > a
> > > > > > > > race
> > > > > > > > > > it wouldn't distract from more
> > important
> > > > things (like paying
> > > > > > attention
> > > > > > > > to
> > > > > > > > > > the wind) nearly as much as furling
> > > > would.  How much mast bend
> > > > > (say
> > > > > > by
> > > > > > > > > > "cord/inches") can you induce in
> > Dynamic
> > > > Equilibrium's mast
> > > > above
> > > > > > the
> > > > > > > > > > spreaders?
> > > > > > > > > >
> > > > > > > > > > As always, I enjoy your posts.
> > > > > > > > > >
> > > > > > > > > > PT
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > > Peter,
> > > > > > > > > > >
> > > > > > > > > > > Michael is talking about Dynamic
> > > > Equilibrium's masthead.  I
> > > > have
> > > > > > my
> > > > > > > > > double
> > > > > > > > > > > backstay attachment point moved
> > aft
> > > > about 6 inches in order to
> > > > > > allow
> > > > > > > > the
> > > > > > > > > > > double backstays to clear the
> > roach of
> > > > my fully battened
> > > > > mainsail.
> > > > > > > > > > >
> > > > > > > > > > > Mast bend is highly dependent upon
> > how
> > > > you setup the tension
> > > > in
> > > > > > the
> > > > > > > > > > standing
> > > > > > > > > > > rigging.  I believe there is there
> > is
> > > > a standing rigging
> > > > tuning
> > > > > > > > > procedure
> > > > > > > > > > on
> > > > > > > > > > > the FAQ page.
> > > > > > > > > > >
> > > > > > > > > > > However, if you modify the
> > masthead
> > > > geometry, like on my boat,
> > > > > the
> > > > > > > > mast
> > > > > > > > > > > operates a little bit differently
> > than
> > > > standard.  The mast can
> > > > > be
> > > > > > > > > modeled
> > > > > > > > > > as
> > > > > > > > > > > a column statically loaded by the
> > > > standing rigging in
> > > > > compression
> > > > > > +
> > > > > > > a
> > > > > > > > > > > cantilever beam point loaded at
> > the
> > > > masthead.  The standard
> > > > > > masthead
> > > > > > > > > > > geometry loads the upper end of
> > the
> > > > mast pretty symetrically.
> > > > > > > > However,
> > > > > > > > > > when
> > > > > > > > > > > you move the double backstay
> > > > attachment point aft, you are
> > > > > > > introducing
> > > > > > > > a
> > > > > > > > > > > factor called "eccentricity" (e)
> > into
> > > > the column loading.
> > > > > > > Basically,
> > > > > > > > > > think
> > > > > > > > > > > of e as the amount by which the
> > > > compression force vector is
> > > > > moved
> > > > > > > off
> > > > > > > > > the
> > > > > > > > > > > neutral axis of the column.  i.e.
> > when
> > > > e = 0, the compression
> > > > > load
> > > > > > > is
> > > > > > > > > > > applied right down the neutral
> > axis of
> > > > the column & you have
> > > > > pure
> > > > > > > > column
> > > > > > > > > > > buckling.  As e is increased, the
> > > > deflection of the column
> > > > under
> > > > > > the
> > > > > > > > > load
> > > > > > > > > > > behaves like a combination of
> > column
> > > > buckling + bending of a
> > > > > > > > cantilever
> > > > > > > > > > beam
> > > > > > > > > > > point loaded on the free end.
> > This
> > > > cantilever beam bending
> > > > from
> > > > > > the
> > > > > > > > > > > eccentricity is in addition to the
> > > > cantilever beam bending
> > > > > induced
> > > > > > > by
> > > > > > > > > the
> > > > > > > > > > > standing rigging.  As far as
> > inducing
> > > > mast bend, it's the
> > > > total
> > > > > > > > > cantilever
> > > > > > > > > > > beam deflection we are interested
> > in
> > > > because it's reproducible
> > > > &
> > > > > > > > > > > controllable.  Column buckling is
> > sort
> > > > of an on/off
> > > > catastrophic
> > > > > > > kind
> > > > > > > > of
> > > > > > > > > > > failure - i.e. virtually no bend
> > up to
> > > > some critical load &
> > > > > then,
> > > > > > > BAM!
> > > > > > > > > > > buckled mast.
> > > > > > > > > > >
> > > > > > > > > > > You might not think that mast bend
> > is
> > > > possible in a masthead
> > > > > rig.
> > > > > > > > > > However,
> > > > > > > > > > > you have to think about the
> > behavior
> > > > of the mast in a 3-D
> > > > world.
> > > > > > As
> > > > > > > > the
> > > > > > > > > > > mast is bent, the height of the
> > > > masthead off the deck is also
> > > > > > > reduced.
> > > > > > > > > > > Although the forestay length
> > attached
> > > > to the front of the
> > > > > masthead
> > > > > > > > > doesn't
> > > > > > > > > > > change, because the masthead drops
> > > > down as well as moving aft,
> > > > > the
> > > > > > > > mast
> > > > > > > > > > can
> > > > > > > > > > > still assume a bent shape.  This
> > bent
> > > > shape can be fine tuned
> > > > by
> > > > > > > > > adjusting
> > > > > > > > > > > the tension of the 4 lower
> > sidestays,
> > > > which collectively
> > > > > restrain
> > > > > > > the
> > > > > > > > > mast
> > > > > > > > > > > from moving from side-to-side as
> > well
> > > > as fore-aft at about the
> > > > > > > > midpoint.
> > > > > > > > > > > The standard double backstay
> > tension
> > > > adjuster with the
> > > > standard
> > > > > > > > masthead
> > > > > > > > > > > geometry is also capable of
> > bending
> > > > the mast.  However,
> > > > because
> > > > > e
> > > > > > is
> > > > > > >  a
> > > > > > > > > > very
> > > > > > > > > > > small value with the standard
> > masthead
> > > > geometry, the required
> > > > > > > backstay
> > > > > > > > > > > tension to achieve a given amount
> > of
> > > > mast bend is much higher,
> > > > > > which
> > > > > > > > > > > compression loads the mast closer
> > to
> > > > the critical column
> > > > > buckling
> > > > > > > > load.
> > > > > > > > > > >
> > > > > > > > > > > Note, this discussion is only
> > > > applicable for the standard rig.
> > > > > > > Never
> > > > > > > > > bend
> > > > > > > > > > > an IMF mainsail mast.
> > > > > > > > > > >
> > > > > > > > > > > Roger Pihlaja
> > > > > > > > > > > S/V Dynamic Equilibrium
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > ----- Original Message -----
> > > > > > > > > > > From: "Peter Thorn"
> > <pthorn at nc.rr.com>
> > > > > > > > > > > To: "The Rhodes 22 mail list"
> > > > <rhodes22-list at rhodes22.org>
> > > > > > > > > > > Sent: Thursday, March 18, 2004
> > 3:27 AM
> > > > > > > > > > > Subject: [Rhodes22-list] Mast
> > Crane
> > > > (was Lou Moore)
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > > Michael et al,
> > > > > > > > > > > >
> > > > > > > > > > > > 12" mast crane?  Very
> > interesting
> > > > idea..  Would the forestay
> > > > > > > tension
> > > > > > > > > > boost
> > > > > > > > > > > > with that much leverage?  Or
> > just
> > > > create mastbend above the
> > > > > > > > spreaders?
> > > > > > > > > > > Has
> > > > > > > > > > > > anyone, in the life of the
> > universe,
> > > > ever created upper mast
> > > > > > bend
> > > > > > > > with
> > > > > > > > > a
> > > > > > > > > > > std
> > > > > > > > > > > > rig?   (You were probably
> > thinking
> > > > about clearing a big
> > > > > roach).
> > > > > > > > > > > >
> > > > > > > > > > > > Afterthought- Does a Harken
> > forestay
> > > > furler have a soft
> > > > track?
> > > > > > If
> > > > > > > > its
> > > > > > > > > > > hard
> > > > > > > > > > > > metal, can you somehow belly the
> > > > Genoa entry for light air?
> > > > > > > > > > > >
> > > > > > > > > > > > PT
> > > > > > > > > > > >
> > > > > > > > > > > > PS - Go fasts are fun, but I'd
> > trade
> > > > them for a favorable
> > > > > shift.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > well now, I think I have to
> > switch
> > > > sides this year,
> > > > > > full-batted
> > > > > > > > main
> > > > > > > > > > > sail
> > > > > > > > > > > > with a 12 inch crane are the way
> > to
> > > > go, single line
> > > > > > > > > > > > > reefing and a soild boom vang,
> > but
> > > > IMF is more convent.
> > > > > > > > > > > > >
> > > > > > > > > > > > > MJM
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > >
> > __________________________________________________
> > > > > > > > > > > > > > Use
> > Rhodes22-list at rhodes22.org,
> > > > Help?
> > > > > www.rhodes22.org/list
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > >
> > __________________________________________________
> > > > > > > > > > > > > Use
> > Rhodes22-list at rhodes22.org,
> > > > Help?
> > > > www.rhodes22.org/list
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > >
> > __________________________________________________
> > > > > > > > > > > > Use Rhodes22-list at rhodes22.org,
> > > > Help? www.rhodes22.org/list
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > >
> > __________________________________________________
> > > > > > > > > > > Use Rhodes22-list at rhodes22.org,
> > Help?
> > > > www.rhodes22.org/list
> > > > > > > > > >
> > > > > > > > > >
> > > >
> > __________________________________________________
> > > > > > > > > > Use Rhodes22-list at rhodes22.org,
> > Help?
> > > > www.rhodes22.org/list
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > >
> > __________________________________________________
> > > > > > > > > Use Rhodes22-list at rhodes22.org, Help?
> > > > www.rhodes22.org/list
> > > > > > > >
> > > > > > > >
> > > >
> > __________________________________________________
> > > > > > > > Use Rhodes22-list at rhodes22.org, Help?
> > > > www.rhodes22.org/list
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > >
> > __________________________________________________
> > > > > > > Use Rhodes22-list at rhodes22.org, Help?
> > > > www.rhodes22.org/list
> > > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > >
> > __________________________________________________
> > > > > > Use Rhodes22-list at rhodes22.org, Help?
> > > > www.rhodes22.org/list
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > > >
> > __________________________________________________
> > > > > Use Rhodes22-list at rhodes22.org, Help?
> > > > www.rhodes22.org/list
> > > > >
> > > >
> > > >
> > > >
> > __________________________________________________
> > > > Use Rhodes22-list at rhodes22.org, Help?
> > >www.rhodes22.org/list
> > >
> > >
> > >__________________________________
> > >Do you Yahoo!?
> > >Yahoo! Mail - More reliable, more storage, less
> > spam
> > >http://mail.yahoo.com
> > >__________________________________________________
> > >Use Rhodes22-list at rhodes22.org, Help?
> > www.rhodes22.org/list
> >
> > __________________________________________________
> > Use Rhodes22-list at rhodes22.org, Help?
>www.rhodes22.org/list
>
>
>__________________________________
>Do you Yahoo!?
>Yahoo! Mail - More reliable, more storage, less spam
>http://mail.yahoo.com
>__________________________________________________
>Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list