[Public-List] Chainplates

via Public-List public-list at lists.alberg30.org
Wed Jan 27 18:53:55 PST 2016 

Actually the chain plate failure starts with  a bearing failure.  Caused by softened wood which allows the bolts to pull thru the wood.  The bolts shear when they pass thru the slots in the fiberglass deck.  Everyone  that I know that's lost a mast because of chain plates has had soft bulkheads.  

Again, When I re-did my chain plates, I used 5/16" bolts with the correct grip length (no threads in contact with nonmetallic) and an aluminum backing plate that captures all 3 bolts (say 1.5" x .25"x 8 or so inches long).  I used aluminum because you can drill it.  I drilled the first hole thru the backing plate , made the first  bolted connection to hold everything together and aligned, and then transferred drilled the rest of the holes thru the chain plate into the backing plate.  The backing plate greatly increases bearing area compared to washers when it comes to bolt pull out  making the approach a significant improvement....my thoughts 

Jim mennucci

Sent from my iPhone

> On Jan 26, 2016, at 9:37 PM, Wes Gardner via Public-List <public-list at lists.alberg30.org> wrote:
> 
> My reply is this- I won't get into a right-way/wrong-way contest here and so I understand that each person is going to need to evaluate the shear strength of the bolts holding their chainplates in place. I believe the documented failure(s) are in truth, in shear. This is where the chainplate actually "cleaves" the bolt clean off in a guillotine-like fashion (can't think of a better way to explain shear). 
> 
> So here's the logic of placing bolts in the "correct" way - simply there's more "meat" at the shoulder end than at the threaded end. Are we good with that all you structural engineers?
> 
> So it stands to reason that if you let the shoulder end of the bolt bear where the actual chainplate contacts said bolt, you'll have more metal there to withstand that shear force. Remember now, we're talkin' shear force here, not tensile force. Am I good with all my structural guys?
> 
> Obviously, buy bolts that have as much shoulder as possible, without having too much.
> 
> I'll leave it there....
> 
> Wes
> 
>> On Jan 26, 2016, at 12:40 PM, Jim Mennucci via Public-List <public-list at lists.alberg30.org> wrote:
>> 
>> randy
>> 
>> if you have washers the same size under the bolt head and the
>> nut...then they're structurally equivalent and bolt direction doesn't
>> matter.  Aesthetically bolt heads would look better in the main cabin.
>> More importantly, best for you to use 5/16 bolts with the correct grip
>> length i.e., insure that you have only the untlhreaded length of the bolt
>> in bearing--no threads in contact with the wood/glass.  When I did the
>> alberg many years ago, I used aluminum flat stock and transfer drilled the
>> 3 bolt holes.  This makes it more improbable that the bolts can pull thru
>> if the wood becomes soft and better distributes bearing loads from the
>> bolts--it's hitting a finish nail with a sledge hammer but is the best of
>> all.
>> 
>> Jim Mennucci
>> 
>> On Wed, Nov 4, 2015 at 6:05 PM, Randy Katz via Public-List <
>> public-list at lists.alberg30.org> wrote:
>> 
>>> Hi,
>>> Yes, I've heard that 5/16 is the way to go. I also understand that
>>> alternating the directions of the bolts is the way to go--like this: top
>>> bolt, head sticking out; second bolt, nut end sticking out; third bolt,
>>> head sticking out.
>>> 
>>> Who knows?
>>> 
>>> Randy Katz
>>> #249 Simple Gifts
>>> Seattle/Bellingham, WA
>>> 
>>> 
>>> 
>>>> Message: 3
>>>> Date: Tue, 3 Nov 2015 23:02:35 -0500
>>>> From: Wes Gardner via Public-List <public-list at lists.alberg30.org>
>>>> To: Glenn Brooks <brooks.glenn at comcast.net>
>>>> Cc: Alberg 30 Public List -- open to all
>>>>       <public-list at lists.alberg30.org>
>>>> Subject: Re: [Public-List] chainplates
>>>> Message-ID: <C41E5648-59D2-4DE2-AF93-7E968758928C at gmail.com>
>>>> Content-Type: text/plain;       charset=us-ascii
>>>> 
>>>> Hey All,
>>>> 
>>>> Did I also mention that someone did in truth "upgrade" to 1/4" shoulder
>>>> bolts but then proceeded to run the bolt in "backwards" such that the
>>>> chainplate still bore on the nut end and therefore the threaded portion
>>> of
>>>> the shoulder bolt, in effect doing absolutely nothing.
>>>> 
>>>> Make sure your bolts are in the "right" way....
>>>> 
>>>> I assume most folks have upgraded to 5/16"????
>>>> 
>>>> Wes
>>>> 
>>>>>> On Nov 3, 2015, at 9:01 PM, Glenn Brooks <brooks.glenn at comcast.net>
>>>>> wrote:
>>>>> 
>>>>> Wes,  no reason to bond the chain plate.  Far better to reinforce the
>>>> knee for the forward lower chainplates with several additional layers of
>>>> fiberglass mat and roving, then drill, bed and reinstall the chainplates
>>>> with 5/16" bolts.  I actually anchored all my upper chainplates with one
>>>> 3/8" bolt, and then added 5/16" bolts.  The biggest risk after
>>> reinstalling
>>>> the chainplates with larger bolts is that the knee might pull away from
>>> the
>>>> hull. Hence the preventative measure of adding DG reinforcement.
>>>>> 
>>>>> It's perfectly fine, actually necessary, to bed the thru deck area
>>> where
>>>> the chain plates emerge from the deck, with 4200 or 5200. The material
>>>> flexes a bit and keeps out water- preventing rot and delamination in the
>>>> knees and bulkheads.
>>>>> 
>>>>> Glenn B.
>>>>> 
>>>>> Sent from my iPad
>>>>> 
>>>>>> On Nov 3, 2015, at 5:44 PM, Wes Gardner via Public-List <
>>>> public-list at lists.alberg30.org> wrote:
>>>>>> 
>>>>>> Yes, at first I was considering bonding the chain plate to either the
>>>> knee or bulkhead but I think maybe the crevice corrosion factor may
>>> prevent
>>>> that.
>>>>>> 
>>>>>> Sent from my iPhone
>>>>>> 
>>>>>>> On Nov 3, 2015, at 7:10 PM, Randy Katz via Public-List <
>>>> public-list at lists.alberg30.org> wrote:
>>>>>>> 
>>>>>>> Greetings,
>>>>>>> 
>>>>>>> Was it Wes talking about replacing bolts and gooping over with 5200?
>>>> If I
>>>>>>> understand the comment correctly, I'd suggest using something other
>>>> than
>>>>>>> 5200 so access to the bolts could easily be had at a later date.
>>> Also,
>>>>>>> leaving the SS hardware open to the air as much as possible can
>>> reduce
>>>>>>> possibilities of crevice  corrosion.
>>>>>>> 
>>>>>>> My apologies if I misunderstood the post!
>>>>>>> 
>>>>>>> Regards,
>>>>>>> 
>>>>>>> Randy Katz
>>>>>>> #249 Simple Gifts
>>>>>>> Bellingham/Seattle WA
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