[Public-list] Chainplate covers?

Roger L Kingsland rkingsland101 at ksba.com
Thu Dec 16 11:44:54 PST 2004 

Thanks for your feedback Don.  Just one minor correction; in fact, Kingsland
has sailed his Alberg a grand total of about 130 miles including a few hours
in the middle of the Chesapeake with 6 foot seas and 25 knots (of course we
all overestimate both);  not even close to the worst weather he has
experienced and he has to admit he was having too much fun driving his "new"
boat to worry about the chain plates.  If you would like to report further
on my sailing experience, I would be happy to send you a copy of my sailing
resume.

Rodger


----- Original Message ----- 
From: "Don Campbell" <dk.campbell at sympatico.ca>
To: "Alberg 30 Public List -- open to all" <public-list at alberg30.org>
Sent: Thursday, December 16, 2004 10:32 AM
Subject: Re: [Public-list] Chainplate covers?


> Guys;
>     This list ought to be about constructive ideas not total criticism.
That
> being said, it must be remembered that Kingsland has not sailed his Alberg
in
> any weather, never mind foul weather or a stiff breeze. Rodger, too many
of us
> kow of excellent designs on paper that have not held up under the reality
of
> usage, whether the design has been by architects or engineers or both. It
might
> help if you tried sailing the boat first, not on rivers,  but on big, open
water
> with the wind at 25 knots before you suggest that the tried and true  (for
not
> just Albergs) might be the best, cheapest and strongest solution,
particularly
> if you are in a breeze that has the boat over so that the waterline is 1/2
way
> up the portlights,  and it is not that difficult to have that happen with
AL30s.
> Watching the rooster tails coming off from stays and winches is a
different sort
> of feeling of safety. Been there, done that with a very old foresail and
really
> deep drafted mainsail.
>     I want the water to stay out of the chainplate through-decks. I don't
really
> care about looks, costs or time. There are different forces at work with
> hydraulic pressures added against the rigging wire and through-deck areas
and we
> are most fortunate that we have to-days' modern polymers as sealants. (In
fact,
> by adding an extra 1/2" of deck with a riser,  I have decreased the
flexibility
> of the chainplate but not made it immovably rigid. Sealants still needed
> though!)
> Don
>
> Roger L Kingsland wrote:
>
> > Mike,
> >
> > I would be happy to comply, but I'm not sure I am the right guy to be
asking
> > for forgiveness.  I throw this stuff out expecting constructive
criticism,
> > understanding "the page" isn't exactly a bastion of new ideas.
Everyone's
> > feedback, even if negative, is greatly appreciated.  Your only comment I
> > take issue with is the reference to time and expense.  Hell, if saving
time
> > and expense were a priority, we wouldn't all be so content throwing
money
> > (and time) into a hole in the water surrounded by fiberglass.
> >
> > Roger
> >
> > ----- Original Message -----
> > From: "Mike Lehman" <sail_505 at hotmail.com>
> > To: "Alberg 30 Public List -- open to all" <public-list at alberg30.org>
> > Sent: Wednesday, December 15, 2004 5:51 PM
> > Subject: Re: [Public-list] Chainplate covers?
> >
> > > Forgive me, Roger, but it seems like a lot of time [and expense] for
> > > something that only takes a few minutes each year [re-caulking the
> > > chainplates]. Hell, in the time we spent sending a replying to these
> > emails,
> > > we could have caulked our chainplates. This is not a weak point in the
A30
> > > construction; it is a proven method for attaching shrouds; it has
> > withstood
> > > the test of time and severe stress and it only becomes vulnerable
through
> > > owner neglect [because the owner let water saturate and damage the
> > bulkhead
> > > because they did not maintain the boat properly].
> > >
> > > Mike Lehman
> > >  ><((((º>¸.·´¯`·...¸><((((º>
> > >
> > >
> > > ----- Original Message -----
> > > From: "Roger L Kingsland" <rkingsland101 at ksba.com>
> > > To: "Alberg 30 Public List -- open to all" <public-list at alberg30.org>
> > > Sent: Wednesday, December 15, 2004 5:11 PM
> > > Subject: Re: [Public-list] Chainplate covers?
> > >
> > >
> > > Mike,
> > >
> > > Thanks for your reply.  I understand all the flexibility stuff
relative to
> > > building structural design where the connections are rigid but the
> > remainder
> > > of the structure is flexible.  Without springs, shock absorbers or
other
> > > gizmos that I haven't seen on stay connections, I would argue it is
not
> > > possible to make a "flexible" connection with a point load such as a
stay.
> > > To me the flexibility issue is how the load is distributed through
> > flexible
> > > materials "downstream" of the rigid point load connection.  That's
where
> > the
> > > flexibility of the diaphragms (hull, deck, bulkheads) comes into play.
I
> > > hope everyone agrees the factory connection must be rigid by the time
it
> > > reaches the upper bulkhead bolt; otherwise the bolts would work
causing
> > > eventual failure.  I am assuming (I hope, correctly) that my detail
simply
> > > moves the point where everything is rigid up about 2".
> > >
> > > With my detail, once the rigid connection to the bulkhead is achieved,
> > there
> > > will be no load on the deck unless A), the bulkhead connection fails;
or
> > B),
> > > there is flex in the 90 degree bend at the top of the chain plate.
The
> > > latter is prevented through a simple structural calculation to confirm
> > > sufficient thickness (that I hope to cajole one of our structural
> > > consultants into doing).  Basically, if the chain plate can't slide up
the
> > > bulkhead and the bulkhead does not move vertically, the portion
against
> > the
> > > bottom of the deck will not apply any upward force.
> > >
> > > To me the issue is weather adding a 3" length of the deck to the rigid
> > > portion of the connection will cause cracking or will the remaining
30+
> > feet
> > > be able to take up the flex lost under the new deck plate.  If the
former
> > > were the case, other areas with rigid plates (mast step, stanchion
bases,
> > > bow bracket, mainsheet traveler) would have similar problems.
> > >
> > > One other consideration is that the "free" portion of the plate (area
> > > between top bulkhead bolt and turnbuckle connection) on the factory
detail
> > > might function as some form of shock absorber necessary to absorb the
> > slight
> > > (probably under 1,000 pounds) eccentric load caused by the inward
angle of
> > > the stays which pulls the whole mess toward the mast.  If this is the
> > case,
> > > extending the vertical tab welded to the deck plate a few inches will
have
> > > the same effect.
> > >
> > > Relative to Alberg/Whitby compromises (IE, design intent), I am sure
> > > economics of a production boat in competition with Pearson came into
play.
> > > I am willing to invest the time to make improvements to those
compromises
> > > but have been careful not to change anything made an effort not to
change
> > > the basic structural flexibility.  For reasons stated above, I don't
think
> > > the detail is a "significant structural modification;" however, Mike
> > > Lehman's comment that he has never seen it done this way certainly
argues
> > > for additional research.
> > >
> > > Thanks everyone for the valued feedback.  Off I go to ponder further.
> > >
> > > Roger Kingsland
> > >
> > > ----- Original Message -----
> > > From: "Meinhold, Michael J" <MICHAEL.J.MEINHOLD at saic.com>
> > > To: "Alberg 30 Public List -- open to all" <public-list at alberg30.org>
> > > Sent: Wednesday, December 15, 2004 2:56 PM
> > > Subject: RE: [Public-list] Chainplate covers?
> > >
> > >
> > > > Roger -
> > > >   I hope that before you make a significant structural modification
you
> > > > understand why Alberg/Whitby chose the system and made the
compromises
> > > > they
> > > > made (I can't say that I can identify all the reasons). I agree with
> > Mike
> > > > Lehman in that a good general principle in ship design is
flexibility,
> > not
> > > > rigidity. What flexibility implies is distribution of load and both
over
> > > > time and space.
> > > >
> > > > You need to carefully consider the path of the load is being carried
.
> > In
> > > > your new joint, the load is carried by the threads of your acorn
nuts.
> > It
> > > > then transfers to the vertical bolts and your L-Bracket. From there
it's
> > > > partly transferred to the bulkhead and partly to the deck, depending
on
> > > > how
> > > > the whole arrangement is tightened up.
> > > >
> > > > In the directly connected chainplates the chain plates transfer the
load
> > > > to
> > > > the bulkhead partly through shear between themselves and the
bulkhead,
> > and
> > > > partly to the bolts and then the bulkhead. No load is carried by the
> > deck.
> > > > I believe it would be a mistake to use the deck to carry any large
> > > > vertical
> > > > load.
> > > >
> > > > As Mike says, most of the time it wouldn't matter, but under trying
> > > > conditions the loads are going to approach the breaking strength of
the
> > > > wire. I would say you want the wire to fail first!
> > > >
> > > >
> > > > Mike Meinhold
> > > > Rinn Duin #272
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: public-list-bounces at alberg30.org
> > > > [mailto:public-list-bounces at alberg30.org]On Behalf Of Roger L
Kingsland
> > > > Sent: Wednesday, December 15, 2004 10:50 AM
> > > > To: Alberg 30 Public List -- open to all
> > > > Subject: Re: [Public-list] Chainplate covers?
> > > >
> > > >
> > > >
> > > > There seems to be an inherent problem with any detail where the
> > chainplate
> > > > passes through an "open" hole in the deck that must be filled with
> > > > sealant.
> > > > At best it is a critical maintenance issue; at worst, a means for
water
> > to
> > > > degrade structural bulkheads.  The chain plate must be flexible to
the
> > > > point
> > > > where it first fastens to the bulkhead which is the top bolt.  At
that
> > > > point
> > > > it must be completely rigid or the chainplate will move and
eventually
> > > > loosen.  Why not move that "point of rigidity" up so it is above the
> > deck
> > > > and a flexible connection through the deck is unnecessary?
> > > >
> > > > As part of the redo of the deck on #148, I have removed the chain
plates
> > > > and
> > > > filled in the holes.  One solution I thought about for the reinstall
was
> > > > to
> > > > make 1/4" SS deck plates (roughly 2" x 3") with the a short piece of
> > > > 1/4" welded vertically on the center to fasten the bottom of the
> > > > turnbuckle
> > > > (basically cutting off the top of the cahinplate and welding it onto
the
> > > > deck plate).  Then make "L" shaped brackets to mount on either side
of
> > the
> > > > bulkhead with the short leg of the "L" mounted against the underside
of
> > > > the
> > > > hull to deck joint (one of the stronger areas of the boat).
Vertical
> > > > holes
> > > > in the short leg drilled near the 90 degree bend would align
> > > > with holes in the deck plate and two bolts through the deck would
carry
> > > > the
> > > > load from the deck to the chainplates bolted to the bulkhead.  All
> > plates
> > > > would be set in a 1/16" resin bed  and bolts would be tightened
> > > > sufficiently
> > > > to get that good old friction connection (none of that squishy 5200
> > > > stuff).
> > > > It seems this solution would be strong, stiff, dry and fairly easy
to
> > > > install.   I have posted a sketch on
> > > > http://home.att.net/~jinnii/roger/perfect/pi_designs.html
> > > > and would appreciate any feedback.
> > > >
> > > > Thanks,
> > > >
> > > > Roger Kingsland
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: "Alfredo" <alberg30sail497 at yahoo.com>
> > > > To: "Alberg 30 Public List -- open to all"
<public-list at alberg30.org>;
> > > > <dk.campbell at sympatico.ca>
> > > > Sent: Monday, December 13, 2004 3:29 PM
> > > > Subject: RE: [Public-list] Chainplate covers?
> > > >
> > > >
> > > > > Since we're on the topic, this is how I intend to someday do the
> > > > > chainplates on Free Spirit.
> > > > >
> > > > > http://www.gizmology.com/V40/Upgrades/chainplateFix/index.html
> > > > >
> > > > >
> > > > > --- "sousa, stephen (ENG)" <sousa_stephen at emc.com> wrote:
> > > > >
> > > > > > Don,
> > > > > >
> > > > > > If you could share the method used for the pattern it would be
> > > > > > appreciated.
> > > > > > This may be one of those items that would fall into the group
> > > > > > purchase area.
> > > > > > It would benefit all Alberg owners and could be very inexpensive
it
> > > > > > we
> > > > > > purchase a large quantity. I would expect that all boats have
the
> > > > > > same
> > > > > > installation for chainplates, so one pattern could be used on
all
> > > > > > boats?
> > > > > >
> > > > > > Thanks,
> > > > > > Stephen
> > > > > >
> > > > > >
> > > > > > -----Original Message-----
> > > > > > From: public-list-bounces at alberg30.org
> > > > > > [mailto:public-list-bounces at alberg30.org] On Behalf Of Don
Campbell
> > > > > > Sent: Sunday, December 12, 2004 7:48 PM
> > > > > > To: Alberg 30 Public List -- open to all
> > > > > > Subject: Re: [Public-list] Chainplate covers?
> > > > > >
> > > > > > Randy
> > > > > >     When I bought #528, I was taken to see a C & C deck which
had a
> > > > > > raised
> > > > > > flat area around the chainplates with the SS plates of which you
> > > > > > speak. I
> > > > > > knew I needed to redo the deck on this boat so incorporated a
raised
> > > > > > flat
> > > > > > area at the chainplates on my new deck. I then went to the scrap
> > yard
> > > > > > and
> > > > > > found some 1/8th stainless plate that was food grade so probably
316
> > > > > > (which
> > > > > > is probaly not what is best for a marine environement, 304 is
> > > > > > stronger and
> > > > > > more durable,  I gather, but strength is not that important
here),
> > > > > > cut it to
> > > > > > size- about 1 1/2" x 2 1/2" and then took it to a machine shop
to
> > > > > > have the
> > > > > > slot cut.  I needed to file the edges a bit to get the
chainplate
> > > > > > angle
> > > > > > correct in the slot but SS is relatively soft, so not difficult
once
> > > > > > in a
> > > > > > vise. I have drilled 2 holes in the plates and drilled and
tapped
> > the
> > > > > > epoxy,
> > > > > > raised flat areas to match so I just tighten the 2 - 1/4 x 1/2
ss
> > > > > > machine
> > > > > > bolts to seal the caulking. Total cost about $25 Canadian when I
did
> > > > > > it 8
> > > > > > years ago -$20 of that  for the machinist. I need to redo that
> > > > > > caulking job
> > > > > > this winter. The raised part of the deck decreased the torque
and
> > > > > > twist on
> > > > > > the chainpates at the deck level too. If you want to know how I
did
> > > > > > the
> > > > > > pattern for the raised flat area let me know.
> > > > > > Don
> > > > > >
> > > > > > Randy Katz wrote:
> > > > > >
> > > > > > > Speaking of chainplates (nice photos of the reinforcement
straps,
> > > > > > BTW)
> > > > > > > has anyone found a source for chainplate covers? They are the
oval
> > > > > > SS
> > > > > > > plates 2-2.5 inches long, slot in the middle, that fit over
the
> > > > > > > chainplate straps where they stick out of the deck. They get
> > > > > > caulked and
> > > > > > > sit over the deck opening, with the chain plate strap coming
up
> > > > > > through
> > > > > > > their middle, and serve to help seal that deck opening.
> > > > > > > I've checked West Marine and a few other stores-- they seem
hard
> > to
> > > > > > find
> > > > > > > at all but ones the size we need I never did come across.
> > > > > > > Anyone know where to get them?
> > > > > > >
> > > > > > > Many Thanks,
> > > > > > > Randy Katz
> > > > > > > #249
> > > > > > > Seattle, WA.
> > > > > > >
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