[Rhodes22-list] A fix for the short furler

Mon Oct 11 10:33:00 EDT 2004

Forestay replaced, Furling tube extended, Boat rigged and in the water,
Life is good.

My new (used) 170 Genoa from Stan works great. I was out yesterday in
approx. 10-12 knots of wind. Sheeted in tight the boat felt good at
15-20 deg of heel. I will get some g.p.s. numbers as soon as I fine tune
the rig.

My major comment is there is nothing as good as replacing the old blown
out sails with decent sails.

When I first replaced my old main with a new (used) main from Stan I
saw a noticeable improvement. Now with the new (used) Genoa I have seen
additional improvement. Less heel, more drive, more defined sweet spot
going to wind.

My Thanks to Stan for sail selection.

My plan is to completely furl the 170 when the wind gets over 15 knots
and fly a 110 jib that hoists on its own wire luff behind the roller
furler.

the 110 jib and Reefing the main works well in 20+ knots. As the wind
exceeds 25 Knots I drop the canvas and motor home...

Bob
Knot Necessary

OK I accept your engineering evaluation.

I have 1 inch OD aluminum tubing that fits tightly inside the 1 .04 ID
Furler tube.

I would put a 4 inch section of the 1.0 inch OD tubing inside the
furling tube and secure it with six 1/8 pop rivets. three each side of
joint equally spaced around the diameter.

Comments?
Bob

>>> cen09402 at centurytel.net 09/28/04 09:21AM >>>
Bob,

Unfortunately, torque does not work that way.  Think about the drive
shaft
on your car.  The entire torque of the engine goes in at the front of
the
driveshaft & it comes out at the rear when it enters the differential. 
I'm
concerned your design will not stand up to the load for very long.

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "Robert Dilk" <Robert.Dilk at TRW.COM>
To: <cen09402 at centurytel.net>; <rhodes22-list at rhodes22.org>
Sent: Tuesday, September 28, 2004 8:32 AM
Subject: Re: [Rhodes22-list] A fix for the short furler

> Thank you for the great comments as always Roger.
>
> You are correct the center bushing will connect the top 16 inches to
> the main furler section. I have tapped and threaded for a # 10 screw
in
> the top and bottom sections to transmit the torque to the upper
> section.
>
> It was my thought that since only the top 16 inches have to driven,
> this modest material will suffice. Please note the lower screw also
> secures the luff through a reinforcing patch.
>
> I do not want to epoxy the center section as this will not allow the
> Forestay to be removed.
>
> Bob
>
> >>> cen09402 at centurytel.net 09/28/04 08:16AM >>>
> Bob,
>
> I'm not quite certain what I'm looking at in those pictures.  I
> understand
> you had to make new plastic end bushings because the old ones were
> probably
> old & brittle & disintegrated when you tried to remove them.  But,
what
> are
> you going to do with the center bushing?  Are you planning to join
the
> two
> pieces of the furling tube with the center bushing vs. welding them
> together?  If so, how do you plan to immobilize the top & bottom
pieces
> of
> the furling tube so they can't rotate relative to each other?
> Remember, the
> head of your genoa is bolted to the top of the furling tube.  During
> furling, the required torque to turn the furling tube is applied at
> the
> furling drum at deck level.  The tack of the genoa is tied to the
> furling
> drum, so it must rotate with the furling drum.  But, the furling
tube
> design
> assumes the furling tube will also transmit the torque up to the
head
> of the
> genoa & cause the entire headsail to wrap around the furling tube in
> sync.
> If your extension is not somehow locked to original lower part of
the
> furling tube; then, the torque will have to be at least partially
> transmitted by the luff tube on the genoa.  This load will take the
> form of
> a distributed shear load all down the length of the luff tube.
> Sailcloth is
> intrinsically at its weakest against this sort of shear loading &
this
> twisting action will shorten the life of the sail, although I can't
say
> by
> how much.  In addition, I would think the sail shape will look
pretty
> odd
> with the leading edge of the sail all twisted out of shape.
>
> Assuming I've analyzed your plan correctly; then, plastic is a poor
> choice
> for the material of construction of the center bushing.  Consider
> refashioning that center bushing out of Al 7075-T6 aluminum alloy &
> using at
> least three
> 10-32 UNF oval head stainless steel set screws on the top & bottom
> sections
> to immobilize them relative to each other.  I would also epoxy these
> set
> screws in place during assembly.  It won't be as strong as welding &
it
> will
> be also be heavier; but, it should lock the upper & lower sections
> together
> and hold them in proper alignment for a long time.
>
> Roger Pihlaja
> S/V Dynamic Equilibrium
>
> ----- Original Message -----
> From: "Robert Dilk" <Robert.Dilk at TRW.COM>
> To: <rhodes22-list at rhodes22.org>
> Sent: Monday, September 27, 2004 9:28 AM
> Subject: [Rhodes22-list] A fix for the short furler
>
>
> > Here is my solution.
> > I was unable to remove the  original split bushings intact, so I
> > measured and designed these from scratch.
> >
> > Note the two end bushing and the center bushing . I will use the
> center
> > bushing to connect the of furling tube to the new extension.
> >
> > The new Forestay is due in Friday. I will tell you how it works
out.
> >
> > Bob
> > S/V Knot Necessary
> >
>
>
>
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>
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