[Public-List] Mast beam almost finished!

[Gordon Laco]

Hi guys

Side forces on the heel of the mast are zero.   The geometry of the rigging turns it all into compression.  And if the rigging let go, for whatever reason, there'd still be zero side force at the mast step because the mast would fall to leeward, pivoting on its heel.  (Unless that cross-wise bolt is in place, in which circumstance the mast would tear up the step plate and what cabin top it managed to keep hold of) 

With that cheery image placed in everyone's minds, I'll say good morning to all of you!

Gord #426 Surprise


On 2013-10-26, at 9:11 AM, Jeffrey <fongemie at gmail.com> wrote:

> Thanks Glen.
> 
> You are probably right about using the through bolts.  I'm still
> trying to get my head around the forces on the last plate. Obviously
> down. But then I'm sure there's some pushing to the side, depending on
> the tack.  What I'm thinking is that the bolts holding down the mast
> plate only need to resist force in sheer, so that depth wouldn't
> matter after a certain point.  Shorter lag bolts that are thicker
> might be stronger than thinner through - bolts?
> 
> 
> jeff
> 
> Jeffrey Fongemie
> 
> Seagrass
> Alberg 30 #116
> Boothbay Harbor Maine
> 
> 
> 
> 
> 
> 
> On Sat, Oct 26, 2013 at 2:19 AM, Glenn <brooks.glenn at comcast.net> wrote:
>> Hi Jeff,  i had the same concern when I replaced my beam.  Eventually I drilled the bolt holes and thru bolted.  My reasoning is that all the boats have these bolts with no failures in 45 years so it is a proven method.   Also I didnt think I would gain anything by using lag bolts.  They wont give you the structural integrity of thru bolts and will likely pull out if the mast ever did go over.  At worst lag bolts have a high risk for  creating pockets for water penetration and early dry rot.
>> 
>> On that cheerful note....
>> 
>> Glenn
>> dolce 318
>> 
>> Sent from my iPad
>> 
>> On Oct 26, 2013, at 12:13 AM, Dominic Amann <dominic.amann at gmail.com> wrote:
>> 
>>> I suspect that bolting through will not introduce much more weakness than
>>> drilled in lag bolts. Bear in mind that the failure you were observing was
>>> a delamination of the beam, and I think through bolts would actually help
>>> prevent that.
>>> 
>>> 
>>> On Fri, Oct 25, 2013 at 4:10 PM, George Dinwiddie
>>> <gdinwiddie at alberg30.org>wrote:
>>> 
>>>> Jeff,
>>>> 
>>>> On 10/24/13 7:17 AM, Jeffrey wrote:
>>>> 
>>>>> Hi everyone,
>>>>> 
>>>>> I'm nearly done replacing my mast beam. I've got the beam in, the
>>>>> tabbing finished and the posts reinforced.
>>>>> 
>>>>> http://216.172.166.167/~**seagrass/ <http://216.172.166.167/~seagrass/>
>>>> 
>>>> Nice work, and a very nice description.
>>>> 
>>>> I still need to decide on how to deal with the bolts, that on the
>>>>> original beam, went through the mast step and right through the beam.
>>>>> I don't think bolts going all the way through the beam are necessary
>>>>> and will weaken the beam. I'm thinking of using some lag bolts that
>>>>> will go an inch or so into the beam.
>>>> 
>>>> - George
>>>> 
>>>> --
>>>> ------------------------------**------------------------------**
>>>> ----------
>>>> When I remember bygone days                         George Dinwiddie
>>>> I think how evening follows morn;            gdinwiddie at alberg30.org
>>>> So many I loved were not yet dead,           http://www.Alberg30.org
>>>> So many I love were not yet born.                          also see:
>>>>              'The Middle' by Ogden Nash     http://idiacomputing.com
>>>> ------------------------------**------------------------------**
>>>> ----------
>>>> 
>>>> 
>>>> 
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>>> 
>>> 
>>> 
>>> --
>>> 
>>> 
>>> Dominic Amann
>>> M 416-270-4587
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> 
> 
> -- 
> ______________
> 
> Jeffrey Fongemie
> _______________________________________________
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