[Rhodes22-list] seat supports

[Kroposki]

Richard,
	My recycled '84 came with a support in the middle of each seat,
probably a PO's attempt to copy Roger with over the counter ss fittings
similar to rail fittings.
                         Ed K

-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Roger Pihlaja
Sent: Friday, September 19, 2003 5:24 AM
To: The Rhodes 22 mail list
Subject: Re: [Rhodes22-list] custom parts?

Richard,

When we first purchased Dynamic Equilibrium, the cockpit seats "creaked"
when they were sat or walked upon.  The noise annoyed me & made the
boat sound like it was cheaply made.  It turns out the bulkhead in front
of
the lazarette compartment is not a structural support for the cockpit
seats.
If you don't believe me; then, check it out & you will find the cockpit
seats are not attached to that bulkhead.  Instead, the cockpit seats
are, in
effect, one long unsupported "beam" from the transom to the cabin
bulkhead.
This simplistic model is especially valid along the inboard edges of the
cockpit seats, which is where the creaking seemed to be coming from.
Let's
model the seats as a simple beam supported at both ends & point loaded
in
the middle as a worst case. The deflection under load, which is what
causes the creaking, is proportional to the unsupported (Length)^3.  To
stiffen the structure, I added two equally spaced support columns on
each
side, port & starboard (Total = 4).  These support columns transfer the
load
from the cockpit seats to the cabin sole.  This reduces the unsupported
beam (Length) by a factor of (1/3)X & stiffens the seats by a factor of
3^3 = 27X.  Viola, no more creaking!  So, that stainless steel support
column in the picture is one of the four.

Can you tell I've done way too many homework problems in Solid
Mechanics this week?  Aren't you sorry you asked?

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "Christine Allison" <sailnut at asan.com>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Thursday, September 18, 2003 9:39 AM
Subject: Re: [Rhodes22-list] custom parts?


> What's the purpose of the stainless support inboard of the propane
tank?
>
> Richard Smith
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> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>
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