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

[Roger Pihlaja]

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
> > > > > > > >
> > > > > > >
> > > > > > > > >
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