[Public-List] foredeck compression
Roger L. Kingsland
r.kingsland at ksba.com
Tue Jan 18 12:06:02 PST 2011
I have read recommendations that, for high load deck hardware like cleats,
one should remove the inner part of the deck around the bolt holes and fill
with epoxy to improve the compressive strength of the deck. I was curious
if this approach was appropriate for an A30.
I asked a materials testing guy I work with to test a 4" round section of
good old 148's foredeck (3 layers of FG and 2 of Masonite, no moisture) and
it failed at 20,000 pounds per square inch. It actually slipped in the
press causing failure at the edge. I suspect, had it been centered in the
press and failed uniformly, the pressure would have been much higher. The
Masonite failed, not the fiberglass. He also tested a piece of 1/2" plywood
which compressed to about half its thickness under the same load (with lots
of water squirting out in the process).
I looked up the clamp load (75% of yield strength) of a 3/8", 316, fine
thread, SS bolt; it is 5,700 pounds (18-8 grade and course threads are
less). Assuming a big bow cleat needing 2-3/8" bolts at each end and a 50%
safety factor, the area of each base of the cleat (less bolt hole areas)
would need to be 0.85 square inches or greater to prevent the bolt from
collapsing the deck.
My conclusion (I am not an engineer but I sure like hanging out with them,
see Sidebar below to learn how to understand them better); it probably isn't
necessary to chop out a cavity in the deck and reinforce the bolt holes with
PS - Wife Jeanne and I drove from Pittsburgh on Jan 8 to attend the
Chesapeake Bay Alberg 30 Association annual dinner. What a great time we
had. We have only been to a few Alberg events but felt at ease and at home
with this lovely group of people. We hope to attend again next year to
discuss the river sailing characteristics of an A30 (seven years of on the
hard is probably long enough). Thanks everyone for your hospitality.
Sidebar - Understanding Engineers
Two engineering students were talking on a university campus when one said,
'Where did you get such a great bike?'
The first engineer replied, 'Well, I was walking along yesterday, minding my
own business, when a beautiful woman rode up on this bike, threw it to the
ground, took off all her clothes and said, 'Take what you want.'
The second engineer nodded approvingly and said, 'Good choice; the clothes
probably wouldn't have fit you anyway.'
Understanding Engineers - Take Two
To the optimist, the glass is half full. To the pessimist, the glass is half
empty. To the engineer, the glass is twice as big as it needs to be.
Understanding Engineers - Take Three
A priest, a doctor, and an engineer were waiting one morning for a
particularly slow group of golfers.
The engineer fumed, 'What' s with those guys? We must have been waiting for
The doctor chimed in, 'I don't know, but I've never seen such inept golf!'
The priest said, 'Here comes the greens keeper. Let's have a word with him.'
He said, 'Hello, George! what's wrong with that group ahead of us? They're
rather slow, aren't they?'
The greens keeper replied, 'Oh, yes. That's a group of blind fire fighters.
They lost their sight saving our clubhouse from a fire last year, so we
always let them play for free anytime.'
The group fell silent.
The priest said, 'That's so sad I think I will say a special prayer for them
The doctor said, 'Good idea. I'm going to contact my ophthalmologist
colleague and see if there's anything he can do for them.'
The engineer said, 'Why can't they play at night?'
Understanding Engineers - Take Four
What is the difference between mechanical engineers and civil engineers?
Mechanical engineers build weapons and civil engineers build targets.
Understanding Engineers - Take Five
The graduate with a science degree asks, 'Why does it work?' The graduate
with an engineering degree asks, 'How does it work?' The graduate with an
accounting degree asks, 'How much will it cost?' The graduate with an arts
degree asks, 'Do you want fries with that?'
Understanding Engineers - Take Six
Three engineering students were gathered together discussing the possible
designers of the human body. One said, 'It was a mechanical engineer. Just
look at all the joints.' Another said, 'No, it was an electrical engineer.
The nervous system has many thousands of electrical connections. ' The last
one said, 'No, actually it had to have been a civil engineer. Who else would
run a toxic waste pipeline through a recreational area?'
Understanding Engineers - Take Seven
Normal people (particularly Albergers) believe that if it ain't broke, don't
fix it. Engineers believe that if it ain't broke, it doesn't have enough
Understanding Engineers - Take Eight
An engineer was crossing a road one day, when a frog called out to him and
said, 'If you kiss me, I'll turn into a beautiful princess.'
He bent over, picked up the frog and put it in his pocket.
The frog spoke up again and said, 'If you kiss me and turn me back into a
beautiful princess, I will stay with you for one week.'
The engineer took the frog out of his pocket, smiled at it and returned it
to the pocket.
The frog then cried out, 'If you kiss me and turn me back into a Princess,
I'll stay with you for one week and do ANYTHING you want.'
Again, the engineer took the frog out, smiled at it and put it back into his
Finally, the frog asked, 'What is the matter? I've told you I'm a beautiful
princess and that I'll stay with you for one week and do anything you want.
Why won't you kiss me?'
The engineer said, 'Look, I'm an engineer. I don't have time for a
girlfriend, but a talking frog, now that's cool.
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