Subject: RE: [harryproa] Re: Anyone there ?
From: "Jim Baltaxe" <>
Date: 1/15/2008, 8:47 PM

Hi All, Rob, Mark especially
Thanks for the very useful comments about rudders. With all the discussion and personalities it is sometimes difficult to follow a substantive argument for very long. I was confused about the implications of the different designs that have been tried and was worried that there are significant weaknesses in the side-hung rudders that Bain used on Aroha. I am reassured by the recent comments while at the same time recognising that improvements will always be "just around the corner" especially with the kind of designs we all seem to like so much.
Now, to talk to the lawyer again .... ;^/


Jim Baltaxe

They said, get a life. I looked on TradeMe but I couldn't find one.

From: [] On Behalf Of Mark Stephens
Sent: Tuesday, 15 January 2008 11:20 p.m.
Subject: Re: [harryproa] Re: Anyone there ?

The biggest negative about the hull hung rudders, well the mk 2 version, is they would be difficult to replace once the shear pins broke. At the moment they are designed to 'break away' in the event of a collision. You would then have to retrieve them from the end of the attachment line and refit them with new shear pins. This may seem like a big disadvantage but it will only happen in a catastrophic event which would render any catamaran with a stuck and broken daggerboard at best and a split hull and bent rudder shaft at worst.

We are not in the business of selling boats using boatshows and brochures. We are enthusiasts trying to promote the proa as a viable alternative to people who understand that Harryproas don't have the decades of development other multis have. Some things, rudders in particular, will go through many iterations before the perfect solution is reached and we keep all of our developments transparent. Maybe not commercially sensible but that's not what we are about. I'm sure all those subscribed to this group are here because of this.

Hopefully the beam mounted rudders will prove to be the best option. Rob has experimented with them and they seem to be working well. The biggest concern was the distance from the boats centre but this has proven OK on Elementarry. Blind Date will be trying them as will Solitarry. As they will kick up in both directions and won't be as draggy let's hope they prove successful.


Rob Denney wrote:


The side of hull mounted rudders work well, as did the in hull dagger
rudders before them and the in hull spade rudders before them. They
are far better than the rudders and daggerboards in most multihulls.
However, none were the perfect solution and this is what we are
looking for. The beam mounted rudders are another (quite large) step
in this direction and have been tested by me on my Elementarry, and
now on my solo boat. They will then be included in the plans.
Anyone who is now at the rudder stage of their build should discuss
the options before they proceed.

Because I believe it is in everyone's interest if I am upfront about
what we are doing and give details of experiments that have been tried
(rail mounted riudders etc) there is a lot of discussion. These are
ideas, not "designs" and they may or may not end up on the plans.

Rudders and daggerboards/keels are the "Achilles heel" of almost all
boats. We are trying to reduce the potential for damage, reduce the
cost and improve the performance rather than taking the stance of the
rest of the industry that there is nothing that can be done about it
and that it is normal for daggerboards to break and hulls to split
when they collide with something and that boats should be confined to
deep water because of the depth of their rudders.

The side of hull rudders in dagger cases do hit a fair bit of water
as can be seen in the Rare Bird video. They may or may not be
draggier than the conventional slot for daggerboards. They are not
likely to cause any handling problems and the spray they kick up is
not likely to reach the cockpit. They do have the advantage that in a
collision, they kick up and in storms, shallow water and on the
mooring, they can be lifted. Their biggest advantage is that in the
event of damage, there are no holes below the waterline.

The beam mounted rudders keep all these advantages and solve the spray
problem. They are also considerably easier to build.



On Jan 15, 2008 1:54 PM, Jim Baltaxe <> wrote:
> Hi Robert
> If what you say about the rudders is true then why is there, or has there
> been, so much worrying about the design of the rudders? Rob and others have
> been concerned about the lower brackets being caught by waves, designs have
> been posted for rudders hung from the akas and there was even a proposal to
> hang rudders from stub akas. I'm not even talking about hanging a single
> rudder/daggerboard from a track on the lee hull and hauling it end to end
> during a shunt.
> I am aware that there are other things than simple strength or turning
> moment involved in rudder design but it seems to be received knowledge that
> rudders are the "Achilles heel" of proas.
> Enjoy
> Jim Baltaxe
> They said, get a life. I looked on TradeMe but I couldn't find one.
> ________________________________
> From: [] On
> Behalf Of Robert
> Sent: Monday, 14 January 2008 4:01 p.m.
> To:
> Subject: [harryproa] Re: Anyone there ?
> -Hi Jim,
> I was certainly impressed with the build when I saw 'Aroha' in the
> earlier stages- I even helped with a bit of the fairing on one of the
> rudders so it must be good! I cant see any problems with the rudders
> as far as slowing the boat down and Rare Bird was a good pilot study
> for the robustness. The brackets are strong enough to take the sailing
> loads so the bit of slapping won't worry them. There is not much
> increase in wetted area if the brackets hit a wave and it would damp
> even further the minimal chance of hobby horsing, which could actually
> improve performance. (I reckon they also provides a means of getting
> on board again from in the water)
> Coming over bars is a good test for robustness maneuverability and
> handling.
> Wish you well in the legal wrangles,and I am sure that Bain would be
> happy for Aroha to go to a good home,
> Robert--
> In, "Jim Baltaxe" <jim.baltaxe@...> wrote:
> >
> > Hi Robert
> >
> > I did get out onto him/her on the last day before Bain so kindly took me
> > to the airport, but unfortunately it was pelting down like mad. We rowed
> > out to the boat, moored in a river near Bain's house and had a good look
> > around but never got off the mooring. We had neither the time nor the
> > breeze to prove much.
> >
> > The boat appears to be very well built and very much what I do want.
> > Enough room for one or two people for extended coastal cruising and the
> > pop-up canopy over the upper cockpit was a cozy place for us to shelter
> > in the rain and talk about, as well as look at, the boat.
> >
> > My only real reservation about the design is the ongoing question of
> > rudder attachments. Aroha's appear solid but the lower brackets
> > certainly will certainly be caught in almost anything more than a flat
> > sea. I really don't know whether that would make much difference to
> > overall performance, though.
> >
> > I did see Aroha come across the bar into the river a couple of days
> > earlier and it was an impressive sight.
> >
> > I am still working on the legal and financial issues so I am hoping that
> > I will be able to make a reasonable offer fairly soon. In the meantime,
> > I do wish Bain good luck and if I miss out, so be it. If everything
> > works well, perhaps I'll be able to get across for another look and a
> > ride later this year.
> >
> > Enjoy
> >
> > Jim Baltaxe
> >
> > They said, get a life. I looked on TradeMe but I couldn't find one.
> >
> > ________________________________
> >
> > From: []
> > On Behalf Of Robert
> > Sent: Thursday, 3 January 2008 11:58 p.m.
> > To:
> > Subject: [harryproa] Re: Anyone there ?
> >
> >
> >
> > -G'day Jim,
> > Sorry to hear of your difficulties. Not a nice situation but there can
> > be an afterlife
> > Did you get a chance to sail on Aroha?
> > Robert
> >
> > -- In
> > <> , "Jim Baltaxe"
> > <jim.baltaxe@> wrote:
> > >
> > > Hi Robert &al
> > >
> > > I'm in exactly the same position which is why I've had my head down
> > for
> > > a while, since Derek's workshop and my visit with Bain. I'm still
> > trying
> > > to work out the "disengagement" (what else do you call a "divorce"
> > from
> > > a legally recognised, long-term, relationship?) so that perhaps I can
> > > get the money together. Sorry Bain but I am trying, really hard.
> > >
> > >
> > > Enjoy
> > > Jim Baltaxe
> > > 209 Derwent Street
> > > Island Bay, Wellington
> > > +64 (04) 938 6018
> > > 027 563 5018
> > > They said, get a life. I looked on TradeMe but I couldn't find one.
> > >
> > > ________________________________
> > >
> > > From:
> > <>
> > [
> > <> ]
> > > On Behalf Of Robert
> > > Sent: Thursday, 20 December 2007 4:16 p.m.
> > > To:
> > <>
> > > Subject: [harryproa] Re: Anyone there ?
> > >
> > >
> > >
> > > -waiting with bated breath for the next development of the Harry. Love
> > > to see the promised photos of Sidecar and Solitarry I am still keen to
> > > get a Harry but health and wealth defy me. The concept still makes the
> > > most sense to me and the boats out there look pretty good. If I had
> > > the cash I'd probably just buy Bain's Aroha and get sailing.
> > > Meanwhile I'm investigating doing a KSS system using polyprop and
> > > epoxy with an end bulkhead with foam ends.
> > > Robert
> > >
> > > -- In
> > <>
> > > <> , "vertiges59" <vertiges59@>
> > > wrote:
> > > >
> > > > Nobody more in this group ?????
> > > >
> > >
> >

No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.2/1224 - Release Date: 14/01/2008 5:39 PM

Recent Activity
Visit Your Group
Y!7 Toolbar

Get it Free!

easy 1-click access

to your groups.

Yahoo!7 Groups

Start a group

in 3 easy steps.

Connect with others.