[Rhodes22-list] keels difference and CR?
Roger Pihlaja
cen09402 at centurytel.net
Sat Jul 17 09:36:07 EDT 2004
Ed,
I don't know about the mast tabernacle on newer Rhodes 22's. On Dynamic
Equilibrium, moving the mast aft would interfere with the pop top. The pop
top slider on my boat runs in the mast groove & bolts directly to the pop
top hatch with a hinge to accomdate pop top operation. Without a fairly
major redesign of the pop top hatch cover, slider/hinge, & the pop top
opening in the cabin roof, there isn't room to move the mast aft even one
inch. I know the pop tops on the newer boats are different than on my 1976
model. But, I am not familiar with the design differences.
The mast does not have to be centered directly over the compression post.
Of course, direct vertical alignment provides the strongest design & most
direct transmission of the mast compression loads to the keel. However, if
the cabin roof is sufficiently strong; then, the mast can be safely moved
from directly over the mast compression post. It's just a matter of
designing in the mechanical strength to handle the off-center compression
loads.
Without doing some computer modeling, it's hard to say how much the mast
would need to be moved aft to balance the helm. However, I would think the
answer would be in the range of a couple of inches. One might be able to
accomplish the same result by increasing the static tilt on the mast by
lengthening the forestay. All else being equal, increasing the amount of
static tilt on the mast (i.e. leaning it more aft), moves the CE of the sail
plan aft & increases the amount of weather helm (or decreases lee helm). It
may very be that the lee helm increasing effects of the 175% genoa, IMF
mainsail, & diamond board are all sufficiently small that their net effect
can be adjusted out by tilting the mast. Do the newer boats come from GBI
with a more pronounced aft tilt on the mast?
Roger Pihlaja
S/V Dynamic Equilibrium
----- Original Message -----
From: "ed kroposki" <ekroposki at charter.net>
To: "'The Rhodes 22 mail list'" <rhodes22-list at rhodes22.org>
Sent: Friday, July 16, 2004 9:54 AM
Subject: RE: [Rhodes22-list] keels difference and CR?
> Michael:
>
> Mast location - is the compression post supposed to be under the
> mast - to distribute loads - prevent cracking of fiberglass and gel coat?
> Yet I know that this is not always the case, because I have looked at
other
> boats, and I know that the do not always match perfectly. Is this a
> question for a Navel Architect?
> Are you talking about an inch or two? If someone took an older hull
> and put in the new diamond board, then he would have to move the mast
> tabernacle aft or forward? What about the boats that Stan routinely
changes
> from standard to IMF? Are the sail measurement changes sufficient to keep
> the center of resistance in the same location?
>
> ED K
>
>
> -----Original Message-----
> From: rhodes22-list-bounces at rhodes22.org
> [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Michael Meltzer
> Sent: Thursday, July 15, 2004 10:23 PM
> To: The Rhodes 22 mail list
> Subject: Re: [Rhodes22-list] keels- is there a difference?
>
> I think he moved the mast, IIRC it was under the compression post at one
> point now it has moved backwards.
>
> MJM
>
> ----- Original Message -----
> From: "Roger Pihlaja" <cen09402 at centurytel.net>
> To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
> Sent: Thursday, July 15, 2004 10:32 PM
> Subject: [Rhodes22-list] keels- is there a difference?
>
>
> > Todd,
> >
> > After writing my response to Roger Brown in the UK & studying the
diamond
> > board pictures on the GBI website, I have my own question for Stan & the
> > list. The design of the diamond board looks to me like it would move
the
> > Center of Resistance (CR) of the keel aft relative to the position of
the
> CR
> > with the early centerboard. All else being equal, moving the CR aft
tends
> > to cause lee helm. The diamond boards are being installed on the newer
> > boats that tend to come equipped with the 175% genoa and the IMF
mainsail.
> > The IMF mainsail has about 10 square feet less area than the standard
> > mainsail. It is my understanding that the missing sail area was all
taken
> > from the roach at the back of the IMF mainsail. Big headsails and
smaller
> > mainsails with less roach both tend to move the Center of Effort (CE) of
> the
> > sail plan forward. Again, all else being equal, moving the CE forward
> tends
> > to cause lee helm. So, the newest Rhodes 22's seem to have 3 features
> that
> > should each cause lee helm.
> >
> > So my question for Stan & the list is: Do the newer boats with the
diamond
> > board, 175% genoas, & IMF mainsails have a lot of lee helm? If not, was
> > some other change like moving the mast aft or the shoal draft keel
forward
> > also made at the same time as the diamond board was adopted?
> >
> > Roger Pihlaja
> > S/V Dynamic Equilibrium
> >
> > ----- Original Message -----
> > From: "Todd Tavares" <sprocket80 at mail.com>
> > To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
> > Sent: Thursday, July 15, 2004 3:06 PM
> > Subject: Re: [Rhodes22-list] Bob Skinner -keels- is there a difference?
> >
> >
> > >
> > > I monitor other lists as well as boat lists. One list for is
> > > elevator people to exchange technical information, etc. Very often
> we
> > > get questions posted by engineering students that are given
> > > assignments to build theoretical elevators in a building 5280 ft
tall
> > > and need to know beam loads and building codes. Or to explain
relay
> > > logic for elevator operation or breakdown of the microprocessor
> > > algorythms for traffic management. Most of these questions are too
> > > complex to explain in an e-mail. Some are impossible.
> > >
> > > What Rhodes 22 owner knows the information that Mr Brown is
> asking
> > > for? or even cares? We would like to know which board points
> better
> > > or goes faster.
> > >
> > > Maybe Mr. Brown is trying to manufacture Rhodes 22 knock-offs in
> > > Great Britian and doesn't have a marine architect or engineer
running
> > > his CAD. I am sure that Stan did not just pull these dimensions
and
> > > specs out of his rear-end, but spent some time and money
researching.
> > > Lordy Lordy remember the stink I caused over getting a copy of an
> > > owners manual posted? Mr Brown is asking for very precise
> > > information, so I am confident that he is intelligent enough to
have
> > > figured out sooner how to unsubscribe himself....but as I only know
> > > too well...for a would-be blogger, it is like the moth to the
flame.
> :
> > > )
> > >
> > > The least we could do for him is to plug his name into a complaint
> > > generator and wait for him to look up all of the "polysyllabic
> > > neologisms" right Michael? :^{D lmao
> > >
> > > Todd
> > >
> > >
> > > ----- Original Message -----
> > > From: "ed kroposki"
> > > Date: Thu, 15 Jul 2004 11:25:14 -0400
> > > To: "'The Rhodes 22 mail list'"
> > > Subject: [Rhodes22-list] Bob Skinner -keels- is there a difference?
> > > >
> > > > Bob,
> > > > Several of us replied to him off list. His replies were .... as
MJM
> > > > mentioned. I doubt that any of us know the cord and centers that
he
> > > wanted,
> > > > not that he would have understood them. We were just curious as
to
> > > why he
> > > > wanted such technical information. If you have the information
that
> > > he
> > > > wanted in the first place, send it to him and see what happens.
> > > > Now that he brought up the subject, I would be interested in tank
> > > > test results of the two systems. If you recall earlier this year
we
> > > has a
> > > > discussion on the pointing ability of the R 22. Is there a
> > > difference
> > > > between the two keels?
> > > > In magazines and other on-line discussions, there recently has
been
> > > > discussion of putting canting keels on very small boats. Do you
> > > supposes
> > > > that Stan will put one on a Rhodes 22? In time for the October
Boat
> > > Show?
> > > >
> > > > Ed K
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: rhodes22-list-bounces at rhodes22.org
> > > > [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Robert
> > > Skinner
> > > > Sent: Thursday, July 15, 2004 10:44 AM
> > > > To: Rhodes 22 mail list
> > > > Subject: [Rhodes22-list] Browned off - Why not?
> > > >
> > > > Thought "Roger Brown" wanted out on the 12th.
> > > > Now he's posting a nasty on the 14th.
> > > > Why not just give him what he asked for in the
> > > > first place?
> > > >
> > > > BTW - I can't find the 7/14 Brown message that MJM
> > > > includes in his (on target) comments about manners.
> > > > Was it killed before it got thru to the membership,
> > > > or did I delete it somehow?
> > > >
> > > & gt; /Bob Skinner
> > > >
> > > > -------- Original Message --------
> > > > Subject: [Rhodes22-list] Please Unsubscribe me!!!
> > > > Date: Mon, 12 Jul 2004 03:14:17 +0100 (BST)
> > > > From: roger brown
> > > > Reply-To: The Rhodes 22 mail list
> > > > To: Rhodes22-list at rhodes22.org
> > > >
> > > > Could you please unsubscribe me! I am tired of
> > > > receiving the gossiping of everybody..
> > > > Roger brown
> > > >
> > > > __________________________________________________
> > > > Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
> > > >
> > > >
> > > > __________________________________________________
> > > > Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
> > > --
> > >
> > > ___________________________________________________________
> > > Sign-up for Ads Free at Mail.com
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> > > References
> > >
> > > 1.
> >
>
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> > 01
> > > __________________________________________________
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> > >
> >
> >
> > __________________________________________________
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> >
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