[Public-List] Mast Support Beam

JS via Public-List public-list at lists.alberg30.org
Mon Feb 8 17:35:35 PST 2016 

    
Mike,
Because this compression happens with both liner and non-liner boats I feel that Bruce's repair actually does not address the deck compression issue. His design helps the wooden beam and it seems to work very well. However, the sagging of the cabin top seams to happening on all Alberg 30s regardless of vintage or design( liner vs non-liner). And is obviously a design flaw.
  If you are comfortable with leaving it compressed and as designed...that is just fine no argument here. I feel that it will continue to sag, however slowly, until something fails. It would seem hard to maintain rig tension with a deck that is constantly, however slight, in on itself. I would never suggest that it just be left alone. These boats are getting old. 
Because my boat is approaching 45+ yrs old and I am finding many items of poor build quality, especially in beam area, the further I did into my boat, I am choosing to go ahead and repair the compression. I recommend other repair there compression as well. I am adding some support in the way of an additional beam just aft of the main beam with knees that will extend down to the bulkhead. Then my mast step will be completely supported. I believe if its worth doing it is worth doing right. I, and many, have a deck that is deformed/compressed from factory design. This is a critical area that supports my rig, for me to feel comfortable for years to come I will repair it properly and give the mast step complete support. Then I will have a deck that will not flex or sag under tension. 
Jason #457 


Sent from my Verizon Wireless 4G LTE smartphone

-------- Original message --------
From: Mike Lehman via Public-List <public-list at lists.alberg30.org> 
Date: 02/08/2016  7:47 PM  (GMT-05:00) 
To: Wes Gardner <wesgardner1952 at gmail.com>, Alberg 30 Public List -- open to all <public-list at lists.alberg30.org> 
Subject: Re: [Public-List] Mast Support Beam 

The mast does not sit directly over the beam. This is because the original 
Carl Alberg design for the Alberg 30 was a 7/8 rig.  But Whitby (and the 
original owners) wanted a mast head rig. So Carl cut several feet of the 
mast and moved it aft to get the center of effort properly aligned with the 
center of resistance. Rather than redesign the entire deck and cabin layout, 
this was a compromise that worked well and produced a fine sailing boat. 
Over the years of sailing the mast compressed the aft part of the deck 
causing a deflection of the deck behind the mast. When the beam fails (on 
the older boats with a wooden beam) the fix is to jack the beam/deck back 
into place, epoxy the beam and add structural support with aluminum plates 
on the fore and aft sides of the beam and through bolt the entire structure 
with 5/16 shoulder bolts. Then add wooden supports under the beam on the aft 
side of the main bulkhead that attach to the bulkhead stiffeners to 
eliminate the twist. This 'repair' was designed by Bruce Rankin who was a 
professor of marine engineering at the US Naval Academy. This has proven to 
be a permanent long-term fix and many of the boats are sailing/racing, 
sometimes in very heavy weather, on the Chesapeake without any further 
deflection of the beam or deck.

-----Original Message----- 
From: Wes Gardner via Public-List
Sent: Monday, February 08, 2016 5:07 PM
To: George Dinwiddie ; Alberg 30 Public List -- open to all
Subject: Re: [Public-List] Mast Support Beam

Hi All,

From what I can tell, the entire deck deflected...there MAY be some
compression of the core, but it doesn't seem so...that ole Masonite may
still be OK.  Everything around it is DRY.  In fact, my entire boat is dry
(except for the cockpit sole).  Around my chainplates, I dug out some sort
of cotton-like material...totally dry!!!

I'm not Irish so I can't really claim their luck :-) but somehow things
have remained dry...my boat has never been raced - no pole gear, no
pole...maybe non-spin at some point boat the wear and tear just isn't
there...

Wes

On Mon, Feb 8, 2016 at 4:47 PM, George Dinwiddie via Public-List <
public-list at lists.alberg30.org> wrote:

> Jason,
>
> You have a balsa core and Wes' boat has a masonite core. The masonite is
> heavier, but doesn't seem to rot the same way that the balsa does.
>
>  - George
>    Calypso, #543
>
>
> On 2/8/16 3:35 PM, Jason S via Public-List wrote:
>
>> Wes,
>>
>> I believe Mike is correct, guy who installed plates didn't fix it
>> properly.
>> That does not mean that it is sound now. You cannot just change the shape
>> of the orginal deck shape and lamination and assume it ok. In order for
>> the
>> deck to deform like that some integrity had to be lost, something had to
>> give or else it would have maintained it's shape.
>>
>> When I removed my mast step and top layer and all the rotten core I could
>> see where the bottom of the core had delaminated when it had become
>> distorted. Probably well before core turned completely rotten. You'd be
>> surprised at how well the fiberglass is adhered to wet core...that balsa
>> is
>> some strong stuff.
>>
>> Will it ever be an issue....I am not sure anyone can say 100%. These 
>> boats
>> get older each year....things that haven't been a problem may start
>> showing
>> their age and will eventually need to be addressed.
>>
>> I still believe that some of the issue has to do with the fact that the
>> mast and mast step is not sitting centered on the beam.
>>
>> Jason
>> #457
>> On Feb 8, 2016 3:15 PM, "Wes Gardner via Public-List" <
>> public-list at lists.alberg30.org> wrote:
>>
>> Hi Mike,
>>>
>>> That my friend is EXACTLY the answer I wanted to hear!!  I could tell by
>>> the caulk that things hadn't moved much (if at all) since that repair 
>>> had
>>> been done.
>>>
>>> Thank you for verifying my observations.  I do intend to clean up some 
>>> of
>>> those on-deck fittings - one isn't even used anymore...
>>>
>>> Wes
>>>
>>> On Mon, Feb 8, 2016 at 3:08 PM, Mike Lehman <sail_505 at hotmail.com>
>>> wrote:
>>>
>>> Wes,
>>>>
>>>> You beam looks fine. The compression you are seeing is from before the
>>>> beam was reinforced. Whoever did the aluminum reinforcement plates,
>>>>
>>> didn't
>>>
>>>> crank the beam all the way up to take out the deflection. But it won't
>>>>
>>> move
>>>
>>>> with those plates in place.
>>>>
>>>> -----Original Message----- From: Wes Gardner via Public-List
>>>> Sent: Monday, February 08, 2016 12:53 PM
>>>> To: public-list at lists.alberg30.org
>>>> Subject: [Public-List] Mast Support Beam
>>>>
>>>> Hi All,
>>>>
>>>> My boat is a non-liner boat #196.  The mast support beam has been
>>>> reinforced with aluminum plate on both sides of the beam.  Looking at
>>>> the
>>>> photo that looks forward, there IS a flat spot in the cabin top.  I’m
>>>> not
>>>> sure whether I’m concerned about it or not.  In that same photo, there
>>>>
>>> are
>>>
>>>> four nuts that hold a fairly substantial pad-eye plate near the base of
>>>>
>>> the
>>>
>>>> mast.  You can see the pad eye with a single Harken block in the photo
>>>> of
>>>> the mast base.  If I eye-ball one against the other, it tells me my 
>>>> mast
>>>>
>>> is
>>>
>>>> resting fairly square on the beam (meaning it’s not too far forward or
>>>> aft.)  Also when I “sound” with my plastic hammer, everything is rock
>>>>
>>> solid
>>>
>>>> as far as the core is concerned.  The other photo of the reinforcing
>>>>
>>> plate
>>>
>>>> looking aft, although it’s not pretty, there are no leaks.
>>>>
>>>> I think I’m content to leave things alone.  Any comments and/or
>>>>
>>> suggestions
>>>
>>>> are always welcome.
>>>>
>>>> https://www.dropbox.com/s/1nbw95vyxmuxify/Mast%20Support%20Beam.jpg?dl=0
>>>> https://www.dropbox.com/s/7nat262in0euf3w/Mast%20Base.jpg?dl=0
>>>>
>>>>
>>>>
>>> https://www.dropbox.com/s/q8hsrt2m5603vy6/Mast%20Support%20Fwd%20Side.jpg?dl=0
>>>
>>>>
>>>>
>>>> Wes #196 Griffin’s Faith
>>>>
>>>
> --
>  ----------------------------------------------------------------------
>   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:
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>  ----------------------------------------------------------------------
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