[C38] Stanchions

Tue Feb 1 02:40:01 EST 2011

Regarding loads on the stanchions I dont have any numbers but some experience of late.  The reason for my querry into the manufacturer was due to some recent damage in a wind storm.  At the end of my dock I use to store a fiberglass sailing canoe its probably 15-18 feet  in length.  About a month ago we had a douzy of a storm, during the night the wind picked up the canoe lifted it about 3 feet and slammed it into the the port stern rail, gate stanchion and the one just forward of the gate.   The two forward stanchions were bent in at safe to say 45 degrees and one heck of a dent in the stern rail about 1/2 the diameter of the tube.  The two forward stanchions both buckled at the base plates as well.   The canoe only travelled about 4 feet from where it was resting until it hit the boat.   This weekend Im pulling the stanchions and the rail, plan to cut the stern rail and have a sleeve welded over it and if the stanchions bases can be flattened Ill reuse them if not new ones.   

Steve
#312 Peregrine
Seattle

________________________________

From: listserve-bounces at catalina38.org on behalf of Anders Finn
Sent: Mon 1/31/2011 9:00 PM
Cc: Catalina 38 Listserve
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> 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> 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
					To: 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> 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
					To: 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> 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] On Behalf Of Anders Finn
					Sent: Friday, January 28, 2011 4:25 PM

					To: 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
					To: 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

					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>

					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>
					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> 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> 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> wrote:
					Hey Steve, 

					I'm not surprised if they were made by Garhauer...... 

					Regards,

					Max

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