[Public-List] Mast Support Beam

[George Dinwiddie via Public-List]

Hi, Jason,

On 2/8/16 8:35 PM, JS via Public-List wrote:
>
>
> Mike,
> Because this compression happens with both liner and non-liner boats

The problem manifests itself very differently on the new boats from the 
old. Some new boats have had trouble with the deck compressing due to 
rotten balsa. The more pernicious problem seems to be that the 
fiberglass pan on which the bulkheads rest can sag, as it's only 
supported at the outboard edges.

> 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.

I'm not a marine architect, but it's my opinion that all boats are 
compromises.

> 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.

If your cabin top is deforming aft of the aluminum beam, then it's 
likely you have rotten core. Replacing that core will likely solve your 
problem more easily than sistering the beam, and with less weight. I 
believe there's an article in the maintenance manual about such a repair.

> 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.

Good luck on that. Everything flexes to some degree. Engineering is the 
art of making the best compromise. Of course, sometimes Whitby was 
building the later boats faster than they could maintain quality 
control. That's not a design issue, though.

  - 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
  ----------------------------------------------------------------------