----- Original Message -----
Sent: Friday, February 24, 2006 2:52
PM
Subject: [harryproa] Re: one rudder proa,
first sail
I was thinking of an over size track in the back of the
wing mast
supporting a gunter This allows a skinnier top section and
flexibility for the gusts and the junction would be almost
seamless.
Robert
--- In harryproa@yahoogroups.com.au,
"Rob Denney" <proa@i...>
wrote:
>
> Could extend them, but easier to use the beams.
Also fun to push
past the limits to see what happens. Not yet sure
what will happen
on the bigger boats with one rudder. A
system like you suggest
would work and be pretty easy to build. I
don't like the idea of
extra headsails as there is nowhere easy to sheet
them and they
involve going on the foredeck. Could be done,
though. For light
air, I like a telescoping mast, but won't know
about this until I
build one.
>
> No rush with the
spreadsheet. I agree about the una rig. Should
get some
sailing photos on Sunday or Monday.
>
> regards,
>
>
rob
> ----- Original Message -----
>
From: David Howie
> To: harryproa@yahoogroups.com.au
> Sent: Friday, February 24, 2006 4:42
AM
> Subject: Re: [harryproa] one rudder proa, first
sail
>
>
> Just some idle thoughts. Could you
extend the rails past the
beams to get the
> rudders
further aft,maybe some support off the hull? What about
a
simple
> system utilizing bungee cord for the two rudder set
up? My idea
would be
> uncleat a line and the rudder
pops up, pull the same line and
cleat it and the
>
rudder is locked down. Sounds harder than the reality.
> So
now, what about harry with a una rig (with a wishbone?) and
rudders
that
> raise and lower easily, then staysail/assymmetic for
light airs
downwind in
> the light
stuff?
> I haven't got around to cleaning up the
materials/price sheet
yet, got busy,
> will try to do it
this weekend.
> BTW I think the una rig looks slick.
>
>
>
> ------ Original Message
------
> Received: Thu, 23 Feb 2006 07:48:34 AM
MST
> From: "Rob Denney"
<proa@i...>
> To:
<harryproa@yahoogroups.com.au>,
<proa_file@yahoogroups.com>
> Subject: [harryproa]
one rudder proa, first sail
>
> g'day,
>
> Sorry I have been off air for the last couple of
weeks. Got a
bit obsessed
> with the single rudder
proa. Anyone with any unanswered
questions or
emails,
> please ask/send them again.
>
> Following on from the successful "una from a schooner"
rig and
success using
> the aft rudder only, I have
tried to build a single rudder that
was moved from
> end
to end. To minimise the work involved, I used the beams as
supports. One
> of our clients was keen on drum
rudders so I thought I would
give these a go.
> Mk 1
was a 300mm dia 300 deep drum. Heavy and draggy so it was
chainsawed
and
> I made a T section with the ball races in the
top. Building it
was possible
> without a lathe,
but would have been much easier with one.
>
>
First plan was to have it running on a couple of strings between
the
beams.
> Looked ok, but did not work. Next was a
couple of 20x 50 strips
of glassed
> timber between the
brackets. This works well, except the rudder
unexpectedly
> floated, a nuisance as I had the runners
on the top of the
strips instead of
> under
them.
>
> Despite the rudder being 33% of the loa
from the end (was 25%
with the fixed
> rudders), it
steered ok. Interestingly, it luffed better than
it bore
away,
> whereas previously any difference has not been
noticable.
Bearing away,
> particularly at slow
speeds was novel. The whole boat would
climb to
windward
> while the bows slowly turned downwind. Had
to stop and reverse
the first time
> I tried to get
around a moored boat. The faster the boat
sailed, the
less
> obvious this effect was. Helm balance was
excellent, could
leave it alone
> from broad to tight
reach (didn't sail ddw) and the boat tracked
straight.
>
> A first for me was that nothing on the prototype
broke! Sailing
tentatively
> reached 13.1 knots on
the gps (not much breeze as you can see in
the
>
pictures), and everything felt really good.
>
> The drum and tracks weigh about the same as the old
daggercase
boxes, but
> could be lighter. The
difference between the 2 rudder schooner
and the
single
> rudder una is about 30 kgs and less drag, which is
a big deal
off a 130 kg
> boat. Must weigh it next
time it is off the trailer.
>
> The system
works, but needs the following changes. A solid stop
instead
of
> rope to keep the rudder vertical, lower the tiller, put
a kink
in the tiller
> extension to get it under the
rails, and runners under the rails
to stop the
> rudder
floating up when shunting. The drum works really well
(thanks Col)
and
> definitely has a place in future proas. The end
to ending is
good for a
> little boat, maybe for a race
boat, probably not worth the
hassles on the
> bigger
cruising ones.
>
> Should have the
fixes done and sailing again on Sunday.
>
> There are
some pictures in the photos section of the harryproa
chat group.
>
> regards,
>
> rob
>
>
>
>
>
>
>
>
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