Subject: Re: [harryproa] Re: harryproa rudder fastening stiffness issue?
From: "Rob Denney" <>
Date: 1/12/2006, 10:15 AM

Robert has answered this p[ost better than I can, but my comments follow.

Hi all,
About horizontal brackets, couldn't they be stiffened by diagonal
ones:  one from the top rudder pintle to bottom bracket base, the
other diagonal from bottom pintle to top base?
A diagonal brace from the lower bracket is going in.  It has already been done on the 12m Harry in the shed.  This, and moving the sheer pins so that they only see sheer loads and not twisting loads will solve the problems we have met with so far. 

To which part of the LW hull structure are the brackets attached? A
bulkhead? And if for some reason they get teared off, is there some
provision that the hull remains structurally relatively sound,
allowing to reach a harbour half an ocean away? Even if there is a
hole in the hull, this could be catered for with two watertight
bulkheads in the LW hull for each rudder. 
There are bulkheads and positive buoyancy in the lee hull.  The brackets are bonded to bulkheads, and as they are above the water,  if they were torn off, the boat would still float, and could still be sailed.   

The rudders are definitely the most difficult problem on a harryproa,
and it would be unfortunate that the HP had repeated reliability
problems when the boat comes out of the "aficionado" circle.
Racing proas had repeated problems 10-20 years ago, which led to
discrediting them in he general sailing public (well I do not speak
about the current 60' tris ;-). The HPs have to avoid that fate!
Absolutely, and I am confident that we will.  In the overall scheme of things, the problems we have had with the rudders are pretty minimal.
So all issues must be solved and the big single issue is rudder
reliability, in the corresponding nav conditions as defined by
european design categories: Bluewater "A" for Visionarry (more than 8
beaufort, more than 4m waves), and probably Coastal "C" for
Elementarry (up to Bf6, 2m waves). And "B" for harry and harrigami
So I am looking forward for a real test: Rob, what about Visionarry
doing Sydney-Hobart ;-)
Hobart is not my decision, unfortunately, but if it was, I would happily do it.  Blind Date may be doing some racing next year, and it is not beyond the realms of possibility that a racing version or 2 will be competing in Europe next year.

--- In, "Rob Denney" <proa@i...> wrote:
> G'day,
> I assume by braces, you mean the horizontal rudder supports?  If so,
I would keep them horizontal.  a) they have now been moved clear of
the water, b) the aft one would act as a scoop and c) they put the
rudder pintles in bending rather than shear, which is much easier to
> regards,
> rob ----- Original Message -----
>   From: Robert
>   To:
>   Sent: Tuesday, January 10, 2006 10:20 AM
>   Subject: [harryproa] Re: harryproa rudder fastening stiffness issue?
>   Thanks Mark and Rob for detailed replies.
>   I was considering making the braces in a foil cross section set about
>   15-20 degrees attack for the forward facing rudder. This would
>   provide stiffenning as well as a bit of lift. Possibly vetilate them
>   in case of severeely depressing the bows. makes sense to put the big
>   quadrant under the floor. When I look at just about any other foil
>   arrangement in other boats they are all vulnerable. Breking waves
>   from behind can put enormous strains on the rudders of most boats.
>   overall your present design looks pretty good and they obvoiously
>   work.
>   Robert
>   --- In, "Mark Stephens" <stephens@o...>
>   wrote:
>   >
>   > I really wouldn't be concerned about the rudder brackets and
>   quadrants from a vulnerability to waves point of view. However the
>   loads they see from leeway prevention are huge. For the last few
>   months, prior to the first sail, I had been concerned about their
>   ability to withstand these loads and was tempted to take them off and
>   beef them up. I decided to leave them for a number of reasons: Better
>   to test them gently and see where the cracks develop, we may need to
>   adjust the rake angle which would also requires a rebuild, there was
>   plenty of other things to get on with. As it happened a shear pin
>   broke which put enormous twisting loads into the case causing
>   breakage. I fixed this quickly to get us sailing again. You can see
>   the repairs in the photos and video.
>   >
>   > On return from the second sail we noticed some hairline cracks on
>   the unrepaired rudder case which I have since repaired, again just
>   strengthening it enough to go sailing again. Rather than completely
>   rebuilding the rudder cases I am interested in keeping the variables
>   to a minimum.
>   >
>   > The triangular brackets that attach the rudders to the hulls are
>   remarkably strong. They may look a bit flimsy but there are 4 per
>   rudder with plenty of carbon and glass and are well triangulated.
>   There are more upwards loads than expected so a 45 deg brace will be
>   put in from the bottom pivot bearing to the hull. When the first
>   rudder broke from the shear pin shearing it caused the top bracket to
>   bend up about 120 degs. When I detached the broken case and quadrant
>   it sprang back into position without damage. I just had to replace
>   the composite pivot bearings.
>   >
>   > The rudders were always going to be the major challenge for us.
>   Consider that they have to rotate 240 degs., raise up and down 2
>   metres, break away if hit (but not under enormous sailing loads) and
>   be balanced under all points of sail. Also keep in mind they are
>   dagger boards, resisting all the sail loads, as well as rudders which
>   have to operate in two directions. The bottom bracket probably is too
>   close to the water. I have raised this by 100mm for Blind Date and
>   subsequent boats.
>   >
>   > Considering the above I think we have a pretty good rudder design
>   once it has been strengthened. We are considering other approaches,
>   such as beam hung rudders, but so far this is the most workable. I am
>   considering replacing the large quadrant wheel with a small one and
>   getting the 'gearing' from a large quadrant under the cockpit floor.
>   >
>   > The slow progress must be frustrating for all of you who are
>   watching this from afar. Now the boat is sailing, repairs or
>   improvements and indeed sailing have to be done in 'play time' of
>   which there is little at this time of year. Harryproa has just landed
>   a very nice contract for 100 carbon fibre masts for GPS aerials on
>   container terminal forklifts. These have to be completed by the end
>   of January so we will be very busy next month.
>   >
>   > A big thank you to Luke for the pictures, video and report.
>   >
>   > Merry Christmas to everyone,
>   > Mark
>   >
>   >
>   > Mark Stephens
>   >
>   > 0431 486814
>   >   ----- Original Message -----
>   >   From: Robert
>   >   To:
>   >   Sent: Saturday, December 24, 2005 10:03 AM
>   >   Subject: [harryproa] Re: harryproa rudder fastening stiffness
>   issue?
>   >
>   >
>   >   Must admit those forward rudders seemed vulnerable. Don't know
>   >   exactly how vulnerable as strong composites can be deceiving.
>   >   Probably the loads on the rudder blades under sailing are greater
>   >   than the loads exerted by waves hitting the supports. Don't see
>   mast
>   >   stiffness as an especial issues. The boat was travelling pretty
>   well
>   >   for the wind strength. Make it too stiff and the shock loads on
>   the
>   >   bearings would be greater. Running stays would need a reddesign
>   of
>   >   the rig in terms of loading and sail shape. Possibly the flex
>   allows
>   >   the boat a little movement without effecting the velocity of the
>   top
>   >   section of the mastas much?
>   >
>   >     Certainly impressive the motion and the speed and lots of nooks
>   and
>   >   crannies for the kids to explore.
>   >
>   >   Loved it
>   >   Robert
>   >
>   >   --- In, "dominiquebovey"
>   >   <dominiquebovey@y...> wrote:
>   >   >
>   >   > Hi all,
>   >   > after seeing the video I have the feeling of two potential
>   stiffness
>   >   > issues on the visionarry and HP in general, the second is
>   rudder
>   >   fixture:
>   >   > I sailed in the irish sea lay May on a 28' monohull, we got got
>   >   pretty
>   >   > rough sees and wether, like Bf 8, wind against current, 15-
>   20'waves
>   >   (I
>   >   > am translating from metric for you anglo-saxon people ;-) where
>   the
>   >   > boat  fell hardly because the front of the waves was almost
>   >   vertical.
>   >   > I wonder how the rudders would bear such shocks, especially the
>   >   front
>   >   > one which takes the brint of the hit.
>   >   > I am especially worried about the horizontal wheel which could
>   be
>   >   > bent/broken by waves? Visionarry is a light boat which will be
>   >   > probably very fast with bare mast in 40-50kn of wind and
>   >   correspnding
>   >   > sea (european category A), so it'd better be TOUGH!
>   >   > And sorry, also the fastening to the hull looks fragile to me,
>   maybe
>   >   > it isn't but it looks so.
>   >   > I would think of an arrangement similar to the catamarans: two
>   >   tillers
>   >   > with a rod joining them, and sticks. But I agree that with this
>   >   you'd
>   >   > have problems fitting an autopilot... HAAA compromise, the
>   basis of
>   >   > engineering!
>   >   > But maybe this is a solution for an emergency steering system,
>   when
>   >   > the cable-based system breaks.
>   >   >
>   >
>   >
>   >
>   >
>   >
>   >
>   >   
>   >   Yahoo! Groups Links
>   >
>   >
>   >
>   >   
>   >
>   >
>   >
>   >
>   >
>   >   --
>   >   Internal Virus Database is out-of-date.
>   >   Checked by AVG Anti-Virus.
>   >   Version: 7.0.344 / Virus Database: 267.14.1/206 - Release Date:
>   16/12/2005
>   >
>   Yahoo! Groups Links
>     a.. To visit your group on the web, go to:
>     b.. To unsubscribe from this group, send an email to:
>     c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of

Yahoo! Groups Links