[Public-List] Mast beam

[Mike Lehman]

The dents appear on the forward lower knees. It is because the shelf if the forward cabin is supposed to provide secondary structural support. Mine was pop riveted to the flange and was loose and provided no support at all. I loosened the forward lowers and jacked out the hull and then glassed the shelf in place...problem solved.

--- Original Message ---

From: "Stephen Gwyn" <stephen.gwyn at nrc-cnrc.gc.ca>
Sent: June 4, 2013 1:49 PM
To: public-list at lists.alberg30.org
Subject: Re: [Public-List] Mast beam


Hi,

To me it looks like the load of the mast (weight plus rigging tension)
is transfered to the beam, which transfers it to the bulkhead.
The bulkhead in turn spreads the load to the hull all along the
edges of the bulkhead where it meets the hull not just at the bottom.
Because the load is spread out over a long line, the join can
weaker per foot then the at the mast-to-beam connection where
all the load is concentrated in an area of less than a square foot.

My head door doesn't close well, but only when I'm hard over
on starboard tack. There is also a small depression around the
mast foot. However, I think it's just the 40 year old fiberglass
creeping. Certainly several A30s (including mine) also have 1/4"
dents around the chainplate knees which are visible you sight
along the sides of the boat.

I had a professional rigger and laminate guy look at it. Despite
the fact they could have made thousands fixing it, they said it
was nothing to worry about.

SG



--
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Stephen Gwyn                       | Tel: 1-250-363-3136
Canadian Astronomical Data Centre  | Fax: 1-250-363-0045
Herzberg Institute of Astrophysics | Cell: 1-250-885-6969
5071 West Saanich Road             | E-mail: Stephen.Gwyn at nrc-cnrc.gc.ca
Victoria, BC, V9E 2E7, Canada      | http://astrowww.phys.uvic.ca/~gwyn/
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