[Public-List] Mast beam almost finished!

[Michael Connolly]

Jeffery, 
Well you beat me to it.  I plan to re-laminate my mast beam this coming summer season. My take on the two center bolts which go all the way through the mast step, cabin top, and beam is that they are unnecessary and were used to make original factory installation and assembly easier, nothing more. Think about it...... for production assembly those two bolts would make holding the beam in place much easier while the bulkheads were drilled for their bolts and the cabin ceiling tabbing was finished. If you examine from a structural point of view, I believe that those bolts are not required.  Since you have fabricated an entirely new beam I would not weaken the beam by drilling through at such a critical location.  I believe that the mast step will stay in place just fine with the four other bolts used which just go into the fiberglass/Masonite core of the coach roof. 
  
Another advantage of not drilling out the two center bolts is that one eliminates two more locations where water can enter the cabin core/mast beam and cause damage. 
  
BTW, your presentation and craftsmanship is first rate, Bravo! 
  
Michael #133 

----- Original Message -----

From: "Jeffrey" <fongemie at gmail.com> 
To: "Mike Lehman" <sail_505 at hotmail.com> 
Cc: "Alberg 30 Public List -- open to all" <public-list at lists.alberg30.org> 
Sent: Saturday, October 26, 2013 9:02:04 AM 
Subject: Re: [Public-List] Mast beam almost finished! 

Yes, I can confirm that my beam had large (~1 inch) holes drilled 
about half way though. Two of them, 5 inches apart right in the 
center. 

-jeff 

On Sat, Oct 26, 2013 at 8:57 AM, Mike Lehman <sail_505 at hotmail.com> wrote: 
> I believe that one of the problems with the original bolts was that Whitby 
> drilled VERY deep countersinks for the nuts on the bottom of the beam. The 
> ones I have seen were drilled about 1/2 way thru the beam and the holes are 
> on the worst possible location where the main downward force is applied. The 
> main contributing factor to beam failure was the glue failed. 
> 
> 
> ~~~_/)_/)~~ Mike Lehman ~~_/)~~~ 
> 
> 
> -----Original Message----- From: Jeffrey 
> Sent: Saturday, October 26, 2013 8:11 AM 
> To: Alberg 30 Public List -- open to all 
> Subject: Re: [Public-List] Mast beam almost finished! 
> 
> 
> 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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______________ 

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