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----- Forwarded Message ----
From: Steve Nichols <aussieswift@xxxxxxxxxxxx>
To: Dave Lindsey <lindsey@xxxxxxxxxxx>
Sent: Monday, 10 September, 2007 9:34:42 PM
Subject: Re: Rudder rip-off
Dave,
Looking at the photos it looks to me like the bottom gudgeon attachment has
sheared off before the top attachment on the bar.
That would appear to me to be the only explanation for the bend in the pin. How
was the lower gudgeon attached? Bolted through or screwed?
Steve
----- Original Message ----
From: Dave Lindsey <lindsey@xxxxxxxxxxx>
To: Swiftsolo <swiftsolo@xxxxxxxxxxxx>
Sent: Monday, 10 September, 2007 3:14:42 PM
Subject: Rudder rip-off
**Just a little info I thought I would pass onto other builders.**
My rudder pulled off my boat today. Mike offered to sail the Red Violin as a
sort of sea trial. It was a beautiful day with winds at about 12-15 kts.
Mike pushed off with no problem. I watched him as he sailed her close hauled
west of the pier. Later I watched as he very skilfully doused the main and
struggled to come in on the jib alone. Eventually it became obvious he
required some assistance.
The rudder had completely ripped off the boat. See the attached pictures.
I think it is fairly obvious what happened. A strong bending moment bent the
pin which lead to the upper gudgeon block pulling away from the bar. I think
this lead to the lower end of the pin bending and the whole works falling
off.
If my assumption is correct, the lesson is that we need to eliminate all
bending moments on the pin. Do not use a spacer as I did. Keep the rudder
box attachment point as close to the gudgeons as possible. Shear is
acceptable, but try to eliminate any and all bending moments.
Now I have to figure out how to fix this mess. Any suggestions. No smart ass
remarks please?
Oh, one final point; I used screw (4) to attach the gudgeon to the bar. I'm
glad I did. I very purposely wanted this to be a failure point vs. breaking
the bar. Now I question if the rudder box should be designed to pivot with
a shear pin. Comments?
David Lindsey
CAN 046
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