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

[Steve Alm]

Roger,  hate to take up your time with this--we know you're pretty busy
these days.  Just one more little question about you supports.  You made the
upper shims out of--UHMWPE.  What's that?

Slim

On 9/20/03 6:40 AM, "Roger Pihlaja" <cen09402 at centurytel.net> wrote:

> 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
>>> __________________________________________________
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>> 
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> 
> 
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