[Rhodes22-list] Why Use Two Support Columns Per Cockpit Seat vs.Only One per Seat?

[kroposki]

Roger,
	O.K!, Now you can do your homework.  All I was saying is that
the previous owner put a support under my seats.  They work ok.  We
usually don't have any big people on the boat.  If I do, I'll get out
your directions and build a proper support. Gee Wiminee...  Why don 
               Ed K

From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Roger Pihlaja
Sent: Saturday, September 20, 2003 7:40 AM
To: The Rhodes 22 mail list
Subject: Re: [Rhodes22-list] Why Use Two Support Columns Per Cockpit
Seat vs.Only One per Seat?

Steve,

I've found that two support columns per cockpit seat don't really get in
the
way of access under the seats.  The aft support columns are actually
rather
nice to have because they provide a place to brace your foot against
when
you are standing at the helm & the boat is heeled over.  This is a great
position to steer from, because the standing helmsman has wonderful
visibility all around.

It would be pretty easy to attach the lazarette bulkhead to the cockpit
seats.  You could just run a bead of something like 3M 5200 polyurethane
adhesive along both sides of the joint & the two pieces would be
permanently
joined.  However, this is such an obvious & easy thing to do; that, one
wonders why it wasn't done at the factory?  My guess is that the two
pieces
are not attached to each other because of thermal expansion
considerations.
But, I really don't know for sure.  I would ask Stan about it before
attaching those two pieces to each other.

The lazarette bulkhead is constructed of 1/4" thick FRP, which would
make it
pretty wimpy as a support column.  However, it would be much better than
nothing, as long as there isn't some overriding reason that would
preclude
joining the lazarette bulkhead & the cockpit seats together.  If Stan
said
it was OK to join them together; then, I would immediately go out &
purchase
a 14 oz tube of 3M 5200, chuck it up in my caulking gun, & have at it,
even
with my four support columns already installed.

As you suggested, one could also design some sort of support column
inside
the lazarette compartment, either right up against or bonded to the
lazarette bulkhead to transfer the loads from the cockpit seats down to
the
hull.  From a solid mechanics design point of view, this strategy could
be
as viable as mine.  I choose to make my support columns look attractive
from
electropolished stainless steel railing pieces/parts & put them in plain
sight.  My strategy utilized mostly off-the-shelf pieces/parts with a
little
cutting, drilling, & fitting.  The only custom pieces/parts I had to
design
& fabricate were the black plastic filler "shims" visible in the picture
at
the top of the support column.  These shims even out the convoluted
underside of the cockpit seats in order to provide a flat spot for the
upper
support column bases to bear against.  I fabricated my four shims from
several pieces of scrap UHMWPE, which I happened to have in my garage at
the
time.  UHMWPE is easy to work with, requiring only wood working tools.
A
structural support inside the lazarette compartment would probably have
to
be all custom made &/or laminated in-situ from FRP or ?.  It's a
question of
esthetics & what materials of construction & fabrication techniques you
are
most comfortable working with.  Hey, I'm just a mechanical engineering
student/nerd.  When it comes to esthetics, you are on your own!

The bottom line is, my cockpit seats haven't creaked in 15+ years, so my
strategy is successful.  There are probably other methods to accomplish
the
same end result, but no one has demonstrated them as yet.

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "Steve Alm" <salm at mn.rr.com>
To: "Rhodes" <rhodes22-list at rhodes22.org>
Sent: Saturday, September 20, 2003 3:00 AM
Subject: Re: [Rhodes22-list] Why Use Two Support Columns Per Cockpit
SeatVs.
Only One per Seat?


> Roger,
>
> Why didn't you just put some kind of support above the lazarette
bulkhead
> where it meets the seat in order to make the bulkhead a support rather
than
> putting in the ss column just inches away?  The disadvantage to having
two
> columns per seat is that it takes away a little access to the area
under
the
> seats.  They get in the way.
>
> Slim
>
> On 9/19/03 8:49 PM, "Roger Pihlaja" <cen09402 at centurytel.net> wrote:
>
> > Ed,
> >
> > The reason why I designed in two support columns per cockpit seat
instead of
> > just one per seat has to do with stiffening the cockpit seat area
around
the
> > lazarette hatch.  As I mentioned in my pervious post, the bulkhead
on
the
> > front of the lazarette compartment is not attached to the cockpit
seats
& is
> > therefore not a structural support for the seats.  Having two
equally
spaced
> > support columns per cockpit seat locates the aft columns right on
the
forward
> > edge of the drain gutter in the rear of the cockpit.  This is a
pretty
good
> > location to provide structural support for the cockpit seat going
across
the
> > boat over the lazarette compartment.  If one were to only use one
support
> > column per cockpit seat; then, these columns would be too far away
from
the
> > lazarette compartment to provide much side-to-side stiffening back
there.
> >
> > Roger Pihlaja
> > S/V Dynamic Equilibrium
> > __________________________________________________
> > Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>
> __________________________________________________
> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>
>


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