[Alberg30] Genoa Travler
Mike Lehman
sail_505 at hotmail.com
Sun Nov 30 20:18:19 PST 2003
Roger,
I am not an engineer, but I have been on an Alberg 30 where we (I) ripped the primary winch and winch pedestal off the deck due to excessive loading. The forces did not affect the genoa track, which is point loaded at the block. If the track was mounted on the deck, I am sure the force would have lifted the deck or pulled the bolts through the deck even with a hefty backing plate. There's something to keep you awake at night! BTW, this incident took place on the first tack of a race, we still took 3rd with only one winch, but the cockpit was a mess throughout the race.
----- Original Message -----
From: Roger L. Kingsland
To: Alberg 30 public list
Sent: Sunday, November 30, 2003 8:30 PM
Subject: Re: [Alberg30] Genoa Travler
Mike;
Thanks for your input, it really is appreciated. Although I don't plan to
race at first, I certainly would not do anything that is not class legal so
I have dropped the idea of moving the genoa traveler inboard. I still don't
think it is a structural issue because A) the load from the Genoa sheet is
probably 1/4 that of a boom vang, and B) the load on a traveler can be
distributed along it's length while a pad eye is a point load.
Relative to the toe rail, the old teak was not salvageable (because the only
way I could get the deformed bolts out was to grind through the side on the
teak to cut off the bolt heads) and, now, there is not one piece of metal
(except the mast plate) connected to the deck. So I have a clean slate. I
have countersunk 3/16" stainless rivets 4" on center (near the outboard edge
of the smooth part) and encased the heads in epoxy. I have also built up
the hull to deck joint with Marine Tex so it is now a finished joint. I
have been messing ad nauseum with the new toe rail detail and will send you
sketches of my current thinking. Thanks for your feedback.
Roger Kingsland
Roger L. Kingsland, AIA
Managing Partner
Kingsland Scott Bauer Associates (KSBA)
N40° 27' 49" W79° 57' 59"
3441 Butler Street
Pittsburgh, PA 15201
www.ksba.com
1(412) 252-1500 X101 - Office & Voice Mail
1(412) 779-5101 - Mobile (no voice mail)
1(412) 252-1510 - Fax
----- Original Message -----
From: "Mike Lehman" <sail_505 at hotmail.com>
To: "Alberg 30 public list" <public-list at alberg30.org>
Sent: Thursday, November 27, 2003 12:06 PM
Subject: Re: [Alberg30] Genoa Travler
> Roger, You need to sail the boat for a couple of years before making this
assumption. I have sailed my A30 for 26 years and have not found this to be
true. Minor bumps do not affect the Alberg. What you are proposing is not a
good idea. The strain on the deck will pull the joint apart. Ask Larry
Morris whose previous owner had installed a pad-eye for a boom vang on the
deck inside the toe rail. The stress on the eye pulled the deck up and
compromised the deck/hull joint. Larry and I removed toe rail and track,
then re-bed everything. I have been on many A30's that have pad-eyes on the
rail thru bolted through the deck/hull joint and there has been no problems.
Moving the track inboard also changes the sheeting angle and would not be
considered legal under class racing rules.
>
> ----- Original Message -----
> From: Roger L. Kingsland
> To: Alberg 30 public list
> Sent: Wednesday, November 26, 2003 2:28 PM
> Subject: Re: [Alberg30] Genoa Travler
>
>
> Mike;
>
> Not to sound like Bill Clinton but, it depends on what your definition
of
> damage is. My argument is that, because the rail connector and the thru
> hull fastener are the same assembly, even small bumps against the rail
will
> work the thru hull joint causing leaks and weakening of the joint. This
> type of "damage" is not visible but how many boats leak at the toe rail?
>
> Roger
>
>
> Roger L. Kingsland, AIA
> Managing Partner
> Kingsland Scott Bauer Associates (KSBA)
> N40° 27' 49" W79° 57' 59"
> 3441 Butler Street
> Pittsburgh, PA 15201
> www.ksba.com
>
> 1(412) 252-1500 X101 - Office & Voice Mail
> 1(412) 779-5101 - Mobile (no voice mail)
> 1(412) 252-1510 - Fax
>
>
> ----- Original Message -----
> From: "Mike Lehman" <sail_505 at hotmail.com>
> To: <public-list at alberg30.org>
> Sent: Wednesday, November 26, 2003 11:51 AM
> Subject: Re: [Alberg30] Genoa Travler
>
>
> > Take it from someone who has hit a number of things with the Alberg
over
> the
> > years - you gotta hit it pretty damn hard to cause any damage. Last
> > encounter: 4-foot waves, 25+ knots and a BIG red channel marker. Ouch!
> >
> >
> >
> > Mike Lehman
> > "Gilleleje" #505
> >
> >
> >
> >
> >
> > ----Original Message Follows----
> > From: "Roger L. Kingsland" <rkingsland101 at ksba.com>
> > Reply-To: Alberg 30 public list <public-list at alberg30.org>
> > To: "Alberg 30 public list" <public-list at alberg30.org>
> > Subject: Re: [Alberg30] Genoa Travler
> > Date: Tue, 25 Nov 2003 16:59:24 -0500
> >
> > Larry;
> >
> > Thanks for your "if it ain't broke don't fix it" vote. I will do the
> count
> > when the polls close.
> >
> > The fact that I have gotten other inquiries like yours below regarding
my
> > docking technique leads me to wonder if I could better occupy
everyone's
> > time discussing docking, not toe rails. I have always thought that
one
> > should hit the dock at an angle of about 30 degrees and only hard
enough
> to
> > have the forward end of the boat bounce out enough so the boat drifts
> > parallel to the dock. If you go too fast the bow will bounce too far
away
> > from the dock (which is only a problem if you can' get a bow line over
the
> > piling) and the impact will not be enough to stop the forward momentum
of
> > the boat (which is only a problem if there is another boat, dingy,
Manatee
> > and/or a lousy, rotten dock that can't even take the impact of a
little
> > sailboat without collapsing right in front of your eyes... in the
way).
> > Perhaps there is a better way I am missing.
> >
> > Roger
> > Old, beat up, toe rail-less #148
> >
> > ----- Original Message -----
> > From: "Larry Morris" <larmor at myexcel.com>
> > To: "'Alberg 30 public list'" <public-list at alberg30.org>
> > Sent: Monday, November 24, 2003 1:06 PM
> > Subject: RE: [Alberg30] Genoa Traveler
> >
> >
> > > I vote for the ain't broke don't fix it solution. By the way, how
hard
> > > do you hit your dock anyway? I think if you hit a piling hard
enough
> to
> > > dislodge the genoa track or egg shape the bolt holes, you will have
> > > bigger problems to deal with.
> > >
> > >
> > > Larry Morris
> > > Solstice #501
> > >
> > >
> > > -----Original Message-----
> > > From: public-list-bounces at alberg30.org
> > > [mailto:public-list-bounces at alberg30.org] On Behalf Of Roger L.
> > > Kingsland
> > > Sent: Sunday, November 23, 2003 3:42 PM
> > > To: dk.campbell at sympatico.ca; Alberg 30 public list
> > > Subject: Re: [Alberg30] Genoa Travler
> > >
> > > Don;
> > >
> > > To answer your question ("Why would you want to try to weaken the
> > > attachment point for wind and genoa forces on an AL 30?"), first
the
> > > short
> > > answer followed by the long answer (for the insomniac Albergers)
that I
> > > composed some time ago to sort out the issues for myself. Any
feedback
> > > would be appreciated.
> > >
> > > Short Answer:
> > > I am sure the "if it ain't broke, don't fix it" crowd will point
out
> the
> > > thousands of Albergs and other boats of the era having a similar
toe
> > > rail
> > > detail that haven't sunk yet. But, this detail simply does not
stand
> up
> > > to
> > > the logic test and, in my humble, newbie opinion, it is definitely
> > > broke.
> > > The problem is the fastening system requiring great strength and
> > > rigidity
> > > (the structural connection between hull and deck) is the wrong type
> > > (shear
> > > vs. friction) and is constantly subjected to forces that weaken it
> > > (bumps
> > > into the dock and genoa sheet loads).
> > >
> > > To me, the solution is to create a good, bonded friction connection
> > > between
> > > hull and deck and to separate connections for the loads on the toe
rail
> > > and
> > > genoa track. Thus the question about moving the traveler inboard.
> > > Also,
> > > the wind load on a 400 square foot sail at 30 knots is under 2,000
> > > pounds
> > > (assuming the sail is still intact in such wind), half of which
goes to
> > > the
> > > sheet. If the sheet enters the block at 45 degrees, the upward
force
> on
> > > the
> > > track is less than 800 pounds (500 pounds at 30 degrees). It is
> > > relatively
> > > easy to distribute with the proper backer plate.
> > >
> > > Long Answer:
> > > I am in the process of replacing my toe rail on #148 and I have the
> > > impression the rivets were meant primarily to hold the deck and
hull
> > > together during chemical bonding. The rivets, which I drilled out
and
> > > filled with Marine Tex were too small and too deteriorated to have
any
> > > appreciable tensile or shear strength and were located near the
outside
> > > edge
> > > of the joint overlap where they would not be effective in creating
a
> > > friction connection (but would do a good job of holding the hull
and
> > > deck
> > > together
> > > while the joint cured). I replaced them with 3/16" SS rivets 4" OC
> > > about
> > > 1-1/2" inboard (my hand still hurts).
> > >
> > > The thru bolted toe rail fasteners (3/16" SS bolts, 6" OC) seem to
be
> > > the
> > > primary hull/deck mechanical fastener. The problem with these is,
> > > because
> > > they also hold the toe rail, they can not be tightened sufficiently
> (the
> > > teak doesn't have sufficient compressive strength) to create a
friction
> > > connection (like that created by a clamp or Chinese handcuffs) at
the
> > > intersection of hull and deck. If the chemical bond fails, the only
> > > remaining bond is the aluminum rivets (which are marginal) and the
> shear
> > > connection created where the SS bolts that pass thru the hull/deck
> > > material.
> > >
> > > A shear connection is only as strong as the surface area that
"pushes"
> > > against the sides of the connector; in this case, the sides of the
> holes
> > > in
> > > the hull and deck (each less than 1/2" thick) forced against the
bolt
> > > shaft.
> > > Also, unless there are no gaps between the fastener and the
> > > material being fastened, the shear connection comes into play only
> after
> > > the
> > > chemical bond fails. So instead of the mechanical fastener adding
to
> > > the
> > > strength of the chemical bond, its strength is only realized after
the
> > > chemical bond
> > > fails. I suspect the chemical bond is stronger so, if a force
> > > sufficient
> > > to break that bond is applied, a second application of the same
force
> > > would
> > > also cause failure of the mechanical fasteners. Glug, glug.
> > >
> > > Ensuring bolt holes are filled with epoxy (often a messy,
hit-or-miss
> > > process) or using fully threaded screws would allow both
connections to
> > > work
> > > in
> > > concert but, the limited strength of a mechanical fastener in shear
> > > would
> > > still be a problem. A screw with a smooth shaft at the upper of
the
> two
> > > layers being fastened will create a friction connection but its
> strength
> > > will be limited the thread grip on the relatively thin lower
material.
> > >
> > > The dual function of the fasteners creates another problem. That
is
> the
> > > fasteners that hold the hull and deck together also hold the toe
rail
> > > (AKA,
> > > bumper) onto the deck. Just a minor bump against a piling can
> > > cause movement of the bolts which will enlarge the hole through
which
> > > the
> > > bolt
> > > passes (I removed bolts forward that had a lazy "S" shape). In
> > > addition,
> > > any eccentric load on the genoa traveler attached to the top of the
> rail
> > > will "work' the thru deck bolts. Close hauled, where loads are
higher
> > > and
> > > more longitudinal, the depth of the toe rail will create shear
> > > resistance.
> > > When loads are transverse, as in when the sail is out (especially
when
> > > held
> > > out by a whisker pole), the thin toe rail does little to prevent
> bending
> > > in
> > > the bolts which are essentially cantilevered from the deck. I
suspect
> > > this
> > > is why we read postings such as this one from George Dinwiddie,
"Most
> of
> > > my
> > > leaks in the lockers under the salon windows have come from leaking
> > > genoa
> > > track bolts." The result is water tight integrity becomes entirely
> > > dependant on the bedding compound (which can also be effected by
> > > movement in
> > > the toe rail) and the sheer connection no longer works in concert
with
> > > the
> > > chemical bond (per above).
> > >
> > >
> > >
> > >
> > > Roger Kingsland
> > > Chief Financial Officer (AKA, check writer)
> > > Mahina Manu, A30 #148
> > > N40° 29.288'
> > > W79° 54.228'
> > >
> > > Author's Disclaimer; This email was produced exclusively by the
sender
> > > and,
> > > in the interest of expediency, without the benefit of editing by
> others.
> > > The sender, thank goodness, is a much better architect/sailor than
> > > speller/editor and, frankly, constantly laments an obvious flaw in
> > > "spell
> > > check," it does not know what the author is thinking. Please
accept
> the
> > > sender's sincere apologies for any "typos" that may appear in this
> > > document.
> > > If present, they are certainly unintended and hopefully do not
cloud
> the
> > > message, or spawn any unnecessary lawsuits.
> > >
> > > ----- Original Message -----
> > > From: "Don Campbell" <dk.campbell at sympatico.ca>
> > > To: "Alberg 30 public list" <public-list at alberg30.org>
> > > Sent: Sunday, November 23, 2003 11:44 AM
> > > Subject: Re: [Alberg30] Genoa Travler
> > >
> > >
> > > > The WTC fell when it went out of column and the support was too
weak
> > > to
> > > hold the weight due to gravititational forces of the mass. Why
would
> you
> > > want to try to weaken the attachment
> > > > point for wind and genoa forces on an AL 30?
> > > >
> > > > "Roger L. Kingsland" wrote:
> > > >
> > > > > I have considered moving my genoa traveler inboard about 2" so
I
> > > could
> > > attach it directly to the deck instead of the toe rail. Would this
be
> > > permitted under the class racing rules?
> > > > >
> > > > > Roger L. Kingsland, AIA
> > > > > Managing Partner
> > > > > Kingsland Scott Bauer Associates (KSBA)
> > > > > N40° 27' 49" W79° 57' 59"
> > > > > 3441 Butler Street
> > > > > Pittsburgh, PA 15201
> > > > > www.ksba.com
> > > > >
> > > > > 1(412) 252-1500 X101 - Office & Voice Mail
> > > > > 1(412) 779-5101 - Mobile (no voice mail)
> > > > > 1(412) 252-1510 - Fax
> > > > >
> > > > >
+---------------------------------------------------------------+
> > > > > | This Old Boat by Don Casey
|
> > > > > |
http://www.amazon.com/exec/obidos/ASIN/0071579931/alberg30-20 |
> > > > >
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