[C38] Stanchions

Anders Finn anders at finn.ws
Wed Feb 2 18:05:47 EST 2011


Steve O,

I agree with you on the wide swing in possible loadings and that testing 
is probably the only way to be sure. . . . Who wants to be our test 
subject?? =)

However, a factor of 10 is probably not realistic on error. A worst case 
could be done assuming that the 200lb person grabs the stanchion alone 
and there are no lifelines to help with support and that, somehow, the 
stanchion does not bend. This would put, as you're saying it a 800ft-lb 
load directly on the toe rail. From what I can see, it LOOKS like the 
profile of the toe rail would make this load acceptable given the shear 
strength of the build material.

Anders

On 02/02/2011 12:27 PM, S Orton wrote:
> Anders,
>   I would attack the load on the stanchions slightly differently.  A 
> 200 lb man falls overboard, grabs the top of a stanchions, exerting a 
> 2g load on the  stanchion  top- and probably bends it.  The toe rail 
> will react a moment of (200lb x 2g) x (2 ft) = 800 ft lbs, which will 
> go into torsion in the toe rail.  Using the top wire to exert the 
> load  will end up sharing the load between stanchions, thus my reason 
> to put all load on one  stanchions.  Now the extrusion must react 800 
> ft lbs of torsion and the difficulty becomes how to calculate the 
> polar moment of inertia and the distance to the extreme fiber for the 
> extrusion to determine the shear stress and this right now I don't 
> know have a clue of how to do with any degree of accuracy- testing 
> would be the best way, as you could be easly off by a factor of 10.  I 
> personally would not want to attach a  stanchions to a toe rail, 
> because the  stanchions are easly damaged (per what Steve S 
> experienced) and a  stanchion is easily replaced vs a toe rail 
> section.  If you want more outboard room, have  stanchions 
> manufactured with a dog leg or bent outboard as Phil Gay suggested.
> Cheers, Steve O
>
> ------------------------------------------------------------------------
> Date: Mon, 31 Jan 2011 21:00:44 -0800
> From: anders at finn.ws
> CC: listserve at catalina38.org
> Subject: Re: [C38] Stanchions
>
> 6063-T5 Aluminum is some strong stuff.
>
> before I could tell anyone if it's going to take the load, I'm going 
> to have to get some input from the community here about what they 
> thing the max load those lines would need to take and in what direction.
>
> BUT, taking some guesses. Stainless aircraft cable can take about 
> 400psi and I THINK that the life lines are 1/4". Assuming we are 
> loading to breaking point of the upper cable 8200lbs and I think the 
> stanchions are about 2" tall (0.6m), that's 16,400 ft-lbs (22,240N-m). 
> I realize that this isn't terribly accurate as I'm just guessing that 
> the stanchions are going to take the same load in all directions.
>
> However, given THAT, in THEORY, you're screwed. My guess is that to 
> shear surface (by look at the cross section) is no more that 1/2" 
> thick. with 6063-T5 having a shear strength of 17,000 psi, you're only 
> going to be able to handle about half of the load in the lateral 
> direction that the cable could take. This is silly though as, the way 
> I calculate, the aluminum is going to take a TON more load than those 
> stainless stanchions could ever stand up to.
>
> I THINK that if you found a secure way to attach the stanchions to the 
> toe rail, you'd be safe.
>
>
> Also, interesting here is it looks like we've now found a manufacturer 
> who can/will sell you new toerails!
>
> Anders
>
> Any other CE's wanna doublecheck my assumptions?
>
> http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6063T5
>
> On 01/31/2011 08:17 PM, Chuck Finn wrote:
>
>     T5 is a lower cost material than T6.  Not as hard or strong, but
>     still some of the strongest aluminum made.  It is a bit more ductile.
>     So, is it strong enough to support those torsional forces?
>     Inquiring minds want to know!
>
>     And Thanks!
>     Chuck Finn
>     Mighty Quinn #114
>     Great Lakes
>
>     On 1/31/2011 8:15 PM, Anders Finn wrote:
>
>         Ask and you shall recieve
>
>         http://tacomarine.com/item--1-9-16-x-1-1-2-Aluminum-Sailboat-Toe-Rail--A62-0009.html
>
>         According to the tech's at Taco Marine, this is our toe rail spec.
>
>         Anders
>
>         On 01/30/2011 12:56 AM, Steve Smolinske wrote:
>
>             I have worm holes on the aft section of the stbd rail far
>             away from the gates.  Good luck fishing that line I did
>             that once took me most of a morning
>
>             Steve Smolinske
>
>             Sent from my iPhone
>
>             On Jan 29, 2011, at 7:55 PM, "Patrick Harpole"
>             <1derful at comcast.net <mailto:1derful at comcast.net>> wrote:
>
>                 *Speaking of stanchions and "worm holes" I got the
>                 pleasure of worming a wire through pulpit (aka
>                 stanchion) because the bow navigation light wiring
>                 failed.*
>
>                     ----- Original Message -----
>                     *From:* Max Soto <mailto:maxsoto at gmail.com>
>                     *To:* Catalina 38 Listserve
>                     <mailto:listserve at catalina38.org>
>                     *Sent:* Saturday, January 29, 2011 5:31 PM
>                     *Subject:* Re: [C38] Stanchions
>
>                     The weirdest thing is that the worm holes on the
>                     rails are not located  near a single fastener. Thy
>                     are located on the sides of the rails... Most of
>                     them on a single side.....
>                     Max
>
>                     Sent from my iPod
>
>                     On Jan 29, 2011, at 6:09 PM, S Orton
>                     <ssorton at hotmail.com <mailto:ssorton at hotmail.com>>
>                     wrote:
>
>                         I should of continued with the "worm hole"
>                         discussion, adding I don't consider it a
>                         structural problem unless a hole develops
>                         at several adjacent fasteners thereby
>                         destroying the clamping force between the hull
>                         and deck.  If it is a hole here and there,
>                         fill it with 5200 and forget it.
>                         Cheers, Steve O
>
>                         ------------------------------------------------------------------------
>                         Date: Sat, 29 Jan 2011 13:26:43 -0500
>                         From: steve.ribble at gmail.com
>                         <mailto:steve.ribble at gmail.com>
>                         To: listserve at catalina38.org
>                         <mailto:listserve at catalina38.org>
>                         Subject: Re: [C38] Stanchions
>
>                         Don't know who made the toerail, but the same
>                         cross section is used by several different
>                         boat builders of the era so it must be an
>                         established extruder...I had the same thing on
>                         a 1980 Mirage.
>
>                         On Sat, Jan 29, 2011 at 1:11 PM, Chuck Finn
>                         <charles at finn.ws <mailto:charles at finn.ws>> wrote:
>
>                             Steve,
>                             I called Garhauer yesterday about
>                             stanchions and the toerail.  Mike told me
>                             they never made the toerail as that is not
>                             something they are set up for.  He was
>                             interested in my idea of a toerail
>                             stanchion, but would make no comment until
>                             he had seen what our toerail looks like. 
>                             He offered to work with me on this after I
>                             got him some specs/pictures of our rail. 
>                             Does anyone have a cross-sectional view
>                             and/or measurements?
>
>                             If I were to guess, I would say our
>                             toerails were made of T6 aluminum as it
>                             extrudes and anodizes well and is one of
>                             the hardest and strongest types.  I have
>                             cut this stuff on a lathe and it does not
>                             remotely behave like ordinary aluminum! 
>                             You need ear protection.   I agree with
>                             Steve O. that low bidder could be our
>                             problem here, which of course would vary
>                             by batches and years.  All aluminum I am
>                             aware of can contain some small levels of
>                             iron, but I recall Grumman successfully
>                             figured out how to reduce this back when
>                             they were the aircraft frame folks.  By
>                             the way, don't try to weld on this stuff
>                             as it requires TIG and a lot of practice! 
>                             One more thing, aluminum can corrode when
>                             exposed.  The neat thing about this stuff
>                             is it almost immediately begins to form an
>                             impermeable skin as part of the corrosion
>                             process that essentially stops further
>                             corrosion and it is able to do this across
>                             a wide PH range.  Now you know pretty much
>                             all I know about this stuff!
>
>                             Regards,
>
>                             Chuck Finn
>                             Mighty Quinn #114
>                             Great Lakes
>
>                             On 1/29/2011 12:19 PM, S Orton wrote:
>
>                                 Phil,  I don't think a backing plate
>                                 is worth the effort- the underside
>                                 clearance/access is very tough.  Use
>                                 oversize washers if possible.  If the
>                                 holes are rotted out, fill with epoxie
>                                 and redrill.  My toe rail also has
>                                 worm holes, near the gates.  I assumed
>                                 the reason was low bidder on the
>                                 extrusions with much more impurities
>                                 included.  The aircraft specs would
>                                 preclude what we a seeing.  Has
>                                 anybody contacted Garhauer about this
>                                 problem?  I can understand corrosion
>                                 at the SS fasteners, but these worm
>                                 holes appear unrelated.
>                                 Cheers, Steve O
>
>                                 ------------------------------------------------------------------------
>                                 Date: Sat, 29 Jan 2011 10:09:44 -0500
>                                 From: steve.ribble at gmail.com
>                                 <mailto:steve.ribble at gmail.com>
>                                 To: listserve at catalina38.org
>                                 <mailto:listserve at catalina38.org>
>                                 Subject: Re: [C38] Stanchions
>
>                                 Great thought about the backing plate,
>                                 Phil.  I've always considered
>                                 stanchions and lifelines to be
>                                 expendable in the event of
>                                 emergencies...that they were basically
>                                 to break your fall, not necessarily
>                                 there to support the weight of the
>                                 world.  That said, obviously I/we
>                                 don't want to replace these things
>                                 every month or two so they need to be
>                                 stout enough.  It seems like one of
>                                 the first things to go, when looking
>                                 at the entire stanchion "system" is
>                                 the through-bolt hole (as Phil
>                                 indicated) and that a backing plate
>                                 would disperse the loads/forces among
>                                 the 4 bolts/holes rather than the two
>                                 that experience expansion when torque
>                                 is applied the the stanchion. Long
>                                 story short, assuming we're all not
>                                 going to run out and replace our
>                                 stanchions for another design, that
>                                 Garhauer already has the the backing
>                                 plate (the base prior to welding to
>                                 the stanchion tube) so it should be an
>                                 easy and relatively inexpensive
>                                 process to upgrade the holding power
>                                 of our existing equipment.
>
>                                 On Fri, Jan 28, 2011 at 8:07 PM, Phil
>                                 Gay <eyriepg at comcast.net
>                                 <mailto:eyriepg at comcast.net>> wrote:
>
>                                     I thought I would explain what I
>                                     think I know about metals from my
>                                     aircraft engineering background. 
>                                     I agree that the toe rail on our
>                                     C38s is an aluminum alloy.  Pure
>                                     aluminum does create its own oxide
>                                     coating which retards corrosion. 
>                                     But, when it is alloyed to
>                                     increase its hardness and
>                                     strength, it loses the ability to
>                                     protect itself unless it has a
>                                     pure aluminum cladding on the
>                                     surface.  Typically these alloys
>                                     have an anodic coating (the dark
>                                     surface on our toe rails) or a
>                                     chemical conversion coating which
>                                     created this protective oxide on
>                                     the exterior surface.
>
>                                     Near the bow of my C38 the toe
>                                     rail has started to pit.  I don’t
>                                     think it has progressed much
>                                     lately with all the rain water
>                                     that we get here in the NW.  I
>                                     doubt that it has weakened the
>                                     extrusion much at all.  I agree
>                                     with the statements about the
>                                     loads on the stanchions.  Later
>                                     model Catalinas have the
>                                     stanchions that fit into sockets
>                                     molded into the toe rail as well
>                                     as being bolted through base
>                                     plates to the deck.  BTW I am
>                                     pretty sure that the deck area
>                                     where the toe rails are attached
>                                     on our C38s is solid un-cored
>                                     fiberglass.  A lot of the
>                                     looseness of the bases is caused
>                                     by the rocking of the bolts, and
>                                     subsequent elongation of the
>                                     holes, because they don’t have
>                                     backing plates to hold them
>                                     vertical.  I think that there are
>                                     ways to securely attach our
>                                     stanchions to the toe rail if they
>                                     are also bolted inboard to the
>                                     deck.  I have also thought about
>                                     having the existing stanchions
>                                     modified so that they angle
>                                     outboard to allow more room to
>                                     pass around the shrouds.
>
>                                     Phil Gay
>                                     C38 049 Que Linda
>                                     Everett WA
>
>
>                                     *From:*listserve-bounces at catalina38.org
>                                     <mailto:listserve-bounces at catalina38.org>
>                                     [mailto:listserve-bounces at catalina38.org
>                                     <mailto:listserve-bounces at catalina38.org>]
>                                     *On Behalf Of *Anders Finn
>                                     *Sent:* Friday, January 28, 2011
>                                     4:25 PM
>
>                                     *To:* listserve at catalina38.org
>                                     <mailto:listserve at catalina38.org>
>                                     *Subject:* Re: [C38] Stanchions
>
>
>
>                                     Really? I thought that toe rail
>                                     was aluminum. Should be pretty
>                                     resistant to salt corrosion. I
>                                     think what my old man is trying to
>                                     say is that the toe rail is at
>                                     least as strong, if not stronger
>                                     than the plywood under the deck to
>                                     which the stanchions are currently
>                                     screwed into. It would be
>                                     interesting to know the dimensions
>                                     of the toe rail if anyone has them
>                                     (I think my dad is going up to
>                                     measure in a few weeks) and I can
>                                     figure out what kind of moment
>                                     could be applied safely to the toe
>                                     rail if one could find a way to
>                                     apply the load evenly.
>
>                                     Anders
>
>                                     On 01/28/2011 04:06 PM, Don Strong
>                                     wrote:
>                                     The toe rail really is not that
>                                     tough.  As well, in salty boats as
>                                     old as mine (1980), the toe rail
>                                     has some indication of chemical
>                                     decomposition along the bottom
>                                     side. I treat my toe rail with
>                                     care. Like the rest of this
>                                     wonderful 30 year old device, I
>                                     hope it lasts longer than I last.
>                                     Don
>
>                                     On 1/28/11 2:15 PM, Anders Finn
>                                     wrote:
>                                     Think about pivot point. If there
>                                     is indeed only two bolts, the only
>                                     thing keeping it from pivoting is
>                                     compression between the plate and
>                                     the toe rail. The bolts are there
>                                     simply to provide a leverage
>                                     point. That's what concerns me.
>
>                                     Anders
>
>                                     On 01/28/2011 02:13 PM, Chuck Finn
>                                     wrote:
>                                     This type of fitting is used by: 
>                                     C&C, Hunter, PDQ, Bayfield, and
>                                     Freedom yachts.  I think the
>                                     footprint is the entire toerail,
>                                     which is significantly stronger
>                                     than our pad fastened to a plywood
>                                     deck....   If I was to worry about
>                                     strength, it would be the shear
>                                     force exerted on the bolts if the
>                                     toerail stanchion base is not a
>                                     good fit with our toerail...  I
>                                     would weld the stanchion to the
>                                     base rather than rely on the
>                                     throughbolt.  I can also comment
>                                     on the strength of at least the
>                                     C&C toerail as I have raced these
>                                     boats and that means bounced a
>                                     time or two off the lines and
>                                     stanchions!  Have crewed Hunters
>                                     as well, but don't remember the
>                                     stanchion design.
>
>                                     I think my next step will be to
>                                     contact Garhauer as they are
>                                     reputed to have first made our
>                                     toerail.  I also could easily
>                                     fabricate my own bases that would
>                                     incorporate Ander's ideas.
>
>                                     But, will it look pretty?
>
>                                     Chuck Finn
>                                     Mighty Quinn #114
>                                     Great Lakes
>
>
>                                     On 1/28/2011 4:16 PM, Anders Finn
>                                     wrote:
>                                     Yeah, I just got a chance to look
>                                     at this. I think Steve is right
>                                     here about a large drop in
>                                     torsional resistance. However,
>                                     that being said, those stanchions
>                                     forward of the cockpit are not
>                                     really THAT strong. I would like
>                                     to see at least a three bolt
>                                     design with a larger outer plate
>                                     to provide some surface to
>                                     disperse the torque to the hull.
>
>                                     Anders
>
>                                     PS. They say they're used on
>                                     Freedom 32's however, from
>                                     pictures, I can't see anything
>                                     resembling a toe rail that would
>                                     support load on them.
>
>
>                                     On 01/28/2011 12:42 PM, S Orton
>                                     wrote:
>                                     Chuck,  If I understand the
>                                     concept correctly, it is a very
>                                     poor structural design.  There is
>                                     no foot print to react the outward
>                                     cantilever force on the stantion-
>                                     you need a four bolt pattern to
>                                     react this force in all
>                                     directions and I only saw two
>                                     fasteners parallel to the toe rail.
>                                     Cheers, Steve O
>
>                                     ------------------------------------------------------------------------
>                                     Date: Fri, 28 Jan 2011 08:27:31 -0500
>                                     From: charles at finn.ws
>                                     <mailto:charles at finn.ws>
>                                     To: listserve at catalina38.org
>                                     <mailto:listserve at catalina38.org>
>                                     Subject: Re: [C38] Stanchions
>
>                                     Max,
>                                     Here is the rigrite url:
>                                     http://www.rigrite.com/Hardware/Stanchions_&_Bases/Stanchion_Bases_SS.html#SS%20Stanchion%20Bases%20that%20Attach%20to%20Toerail
>                                     <http://www.rigrite.com/Hardware/Stanchions_&_Bases/Stanchion_Bases_SS.html#SS%20Stanchion%20Bases%20that%20Attach%20to%20Toerail>
>
>                                     As you can see, this would put the
>                                     stanchion on the outside edge of
>                                     our toerail and would eliminate
>                                     the base.  This would result in a
>                                     lot of room on the deck.  I am
>                                     thinking of using two of the bases
>                                     for the gate and then moving
>                                     forward.  My issue about this
>                                     would look is that I will have to
>                                     connect to the stern rails and bow
>                                     pulpit, which would remain as they
>                                     are.
>                                     I would also have to fill all the
>                                     holes in the deck from where the
>                                     plates were and re-route the
>                                     holding tank vent, but that would
>                                     be worth it for the extra room on
>                                     deck and the elimination of
>                                     possible leaks.
>
>                                     What to our C38 folks think?
>
>                                     Chuck Finn
>                                     Mighty Quinn #114
>                                     Great Lakes
>
>
>                                     On 1/27/2011 11:21 AM, Max Soto
>                                     wrote:
>                                     Chuck, Did you send a link for the
>                                     rigrite stanchions?
>                                      Regards,
>
>                                     Max
>
>                                     2011/1/26 Chuck Finn
>                                     <charles at finn.ws
>                                     <mailto:charles at finn.ws>>
>                                     One way I know it is sailing
>                                     season is the scrape on my shin
>                                     obtained as I climb from the cabin
>                                     to the cockpit.  The other wound
>                                     is the bruises on the side of both
>                                     legs as I bang into the
>                                     stanchions.  I love the look of
>                                     our boats, but the design idea
>                                     that the stanchions should follow
>                                     the inward bend of the tumblehome
>                                     really does not work for me. 
>                                     There just is not enough deck for
>                                     a guy my size.  I am still
>                                     considering bending and re-welding
>                                     the current stanchions into a
>                                     vertical position, but perhaps
>                                     even a better solution would be to
>                                     remove the current stanchions
>                                     altogether and going with a toe
>                                     rail stanchion like you see on C&C
>                                     yachts. Rigrite.com
>                                     <http://rigrite.com/> has these.  
>                                     Attaching stanchions directly to
>                                     our toerail seems to be a viable
>                                     option as the rail is really heavy
>                                     duty.  Additionally, you can buy
>                                     the bases and use the current
>                                     tubing assuming it is not the
>                                     light weight stuff Tom has
>                                     commented on.   This would give us
>                                     a lot more deck space for size 11
>                                     feet.
>                                     Just thinking aloud at this point,
>                                     but I really am tired of the bruising!
>
>                                     Chuck Finn
>                                     Mighty Quinn #114
>                                     Great Lakes
>
>
>                                     On 1/25/2011 3:25 PM, Max Soto wrote:
>                                     Good to know that they share the
>                                     same foot print... If the
>                                     removable stanchion's base also
>                                     fits, I'll go for that one next
>                                     time..... A little heavier, but if
>                                     they bend, it will be so much
>                                     easier to replace.......
>                                     Thanks, Max
>
>                                     2011/1/25 Steven Ribble
>                                     <steve.ribble at gmail.com
>                                     <mailto:steve.ribble at gmail.com>>
>                                     Max, yes...same foot print.
>                                      Garhauer has a square-ish base
>                                     that I think are for removable
>                                     stanchions and a one
>                                     that's trapezoidal for the
>                                     solid/fixed type, which is what
>                                     mine are (also characterized by
>                                     the "flat top").  I can't speak to
>                                     the quality comment that Tom
>                                     refers to, I just know mine have
>                                     been on the boat for 30 years and
>                                     only needed to be replaced because
>                                     the over-wintering force exerted
>                                     by the shrinkwrap caused them to
>                                     bend.  I thought I saw
>                                     reinforced/gate style stanchions
>                                     on their website, but don't know
>                                     about the footprint.
>
>                                     On Tue, Jan 25, 2011 at 12:13 PM,
>                                     Tom T. <tdtron at earthlink.net
>                                     <mailto:tdtron at earthlink.net>> wrote:
>
>                                     After hurricane Dennis (the
>                                     Menace) skirted Tampa Bay a few
>                                     years ago with a near miss, we got
>                                     tangled up with a piling with the
>                                     surge and had our starboard
>                                     lifelines damaged along with the
>                                     stanchions on that side.
>
>                                     I replaced the stanchions near the
>                                     rail at the aft end of the cabin
>                                     with Catalina Direct stanchions. I
>                                     replaced both sides so they would
>                                     match.  My boat had standard
>                                     stanchions and those stanchions
>                                     should have been the reinforced
>                                     gate entry types which are heavier
>                                     and more expensive.
>
>                                     I didn't shop Garhauer and I
>                                     probably should have but the
>                                     original stanchions were JUNK so
>                                     anything was an upgrade!  The
>                                     metal in the replacement
>                                     stanchions was much heavier gage
>                                     and with the reinforced foot
>                                     design of the gate type stanchion
>                                     there was no comparison between
>                                     quality or strength of the two types.
>
>                                     The reason I bring this up is some
>                                     of our members may have stanchions
>                                     like the ones I replaced which may
>                                     be a disaster waiting to happen. 
>                                     If the stanchions at the front of
>                                     the gate are like the thin, weak
>                                     ones like I had they could fail. 
>                                     The thin tube original stanchions
>                                     may be OK for middle of the
>                                     lifeline mounts but where the
>                                     gates terminate they are inadequate
>
>                                     Tom Troncalli
>
>                                         ----- Original Message -----
>                                         *From:*Max Soto
>                                         <mailto:maxsoto at gmail.com>
>                                         *To: *Catalina 38 Listserve
>                                         <mailto:listserve at catalina38.org>
>                                         *Sent:*1/25/2011 12:00:20 PM
>                                         *Subject:*Re: [C38] Stanchions
>
>                                         Steve, do they have the same
>                                         footprint???
>                                         Regards, max
>
>                                         Sent from my iPod
>
>
>                                         On Jan 25, 2011, at 9:30 AM,
>                                         Steven Ribble
>                                         <steve.ribble at gmail.com
>                                         <mailto:steve.ribble at gmail.com>>
>                                         wrote:
>
>                                             Our stanchions are
>                                             Garhauer...I replaced a
>                                             couple last season...about
>                                             $50 each.
>
>                                             On Mon, Jan 24, 2011 at
>                                             7:06 PM, Max Soto
>                                             <maxsoto at gmail.com
>                                             <mailto:maxsoto at gmail.com>> wrote:
>                                             Hey Steve,
>
>                                             I'm not surprised if they
>                                             were made by Garhauer......
>
>                                             Regards,
>
>                                             Max
>
>
>
>
>
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