----- Original Message -----

From: Robert

To: harryproa@...

Sent: Thursday, February 09, 2006 1:55 PM

Subject: [harryproa] Re: Sunday sail

I'm intrigued. Trying to thnk of all the parameters and can't really
think of any that make sense.
Weight. Easy to check by adjusting weight but doesn't seem to be
sufficient for such a large contrast. Easy to test.

CoE. Should be pretty similar with the una compared with the
schooner, unless the combination of the two sails brings it forward.

Efficiency of rig.Possibly the single rig is so much more eficient
that it pushes forward so much more than sideways and so reduces drag
on the hull ( and I have to eat my words on the UNA/schooner rig
question)

Hull drag characteristics. There is a hump in the speed drag
characteristics of the hull.

Something in the conditions such as currents or chop that was
sufficiently different

Or something else I am not imaginative enough to thnk of.

Curious,
Robert

--- In harryproa@..., "Rob Denney" <proa@i...> wrote:
>
> G'day,
>
> I sailed with both rigs and one rudder, still felt like it was
pushing a lot more water than with the single rig.  Not sure about
the rake.  The new rudder is raked aft, so may be able to compare.
>
> regards,
>
> Rob
>   ----- Original Message -----
>   From: Robert
>   To: harryproa@...
>   Sent: Wednesday, February 08, 2006 7:58 AM
>   Subject: [harryproa] Re: Sunday sail
>
>
>   Rob,
>   Is it possible that the decreased resistance by lifting the
forward
>   blade and the raking forward of the rear could contribute to this?
>   regards,
>   Robert
>
>
>   --- In harryproa@..., "Rob Denney" <proa@i...>
wrote:
>   >
>   > G'day,
>   >   Hi Rob
>   >
>   >   Did you just use one of the schooner's rigs in a new central
hole?
>   >   Yes
>   >
>   >
>   >   Did you have to restrain the forward rudder or just ignore it?
>   >
>   >   Initially I kept it aligned with the flow (ie restrained it),
but
>   it was easier to keep the rear one aligned so I steered with the
>   front one.   Both took a lot of concentration, so I pulled the
front
>   one up altogether, which was far easier than either.
>   >
>   >   Did you move aft to keep the bow up?
>   >
>   >   I sat just forward of the aft beam and the angle between bow
and
>   hull bottom popped into view regularly.  Sitting in the middle
>   depressed it, but not by much, probably no more than level.  This
is
>   illogical,  I will check it next time as it is relevant for the
>   bigger boats where the weight cannot be moved.
>   >   regards,
>   >
>   >   Rob
>   >
>   >
>   >   Regards,
>   >
>   >   Col C
>   >
>   >
>   >   --- In harryproa@..., "Rob Denney" <proa@i...>
>   wrote:
>   >   >
>   >   > G'day,
>   >   > Went sailing on Sunday in Elementarry to assess una rigs vs
>   >   schooners.  15 knots of breeze, solo, with 11 sqm/118 sq' of
>   sail. 
>   >   This is half a Tornado sail area but the sail itself probably
>   less
>   >   than 75% as effective due to the mast and the set up.
>   >   >
>   >   > Simply amazing.  It is a different boat. Flies over the
water
>   >   rather than trying to force it's way through it.    Steered
>   itself,
>   >   the bows were up upwind and top speed was not a lot different
to
>   the
>   >   schooner rig (16.4 knots max, vs 16.8 with the schooner in
>   similar
>   >   conditions).  Followed a Tornado upwind, was pointing as
high,
>   but
>   >   going slower.  Quicker than a racing Hobie 16 reaching.   Not
>   many
>   >   other boats were sailing.  Not much sea, but occasional large
>   wakes
>   >   from powerboats.  Handled with aplomb, although wet if the
beam
>   hits
>   >   the wave top.
>   >   >
>   >   > I steered using only the aft rudder which was similar to
>   steering
>   >   a conventional boat, the forward location making up for no
>   >   daggerboard, the oversize rudder making up for the lack of
lever
>   >   arm.   Shunting was very easy (a nuisance going to leeward to
>   lift
>   >   and lower the rudders), never got close to getting into irons
or
>   >   caught aback.   Downwind, it just got up and went. 
Occasionally
>   >   buried the bow, but did not slow it down.    It is now
definitely
>   a
>   >   boat anyone could sail solo and one which I look forward to
>   teaching
>   >   my 4 year old daughter how to sail on.  Should also be able
to
>   look
>   >   at the gps while sailing, rather than only the max speed at
the
>   end
>   >   of the day. 
>   >   >
>   >   > Interestingly, I only flew a hull once or twice the whole
time
>   >   (too lazy to get off the windward hull, too amazed by how
>   >   comparatively easy it all was to bother with pushing the
limits),
>   >   which suggests that the rig is under utilised, something
>   supported
>   >   by looking at it.  A new wing mast will help this.  I was
going
>   to
>   >   increase the una rig sail area, but think I will go with the
same
>   >   area, but with a wing mast, maybe forward raked to reduce
sheet
>   >   loads.  Also building a single rudder setup so I don't have
to
>   raise
>   >   and lower them each shunt.
>   >   >
>   >   > The single rig is quicker to rig and derig; An hour and a
half
>   >   from arriving at the ramp to sailing, but at least half of
this
>   was
>   >   one off jobs that needed doing.  Also easier to right after a
>   >   capsize and 4 grand cheaper.
>   >   >
>   >   > I am not a lot wiser about how long boats should be for a
given
>   >   sail area, but am pretty certain that it is much longer than
they
>   >   currently are. 
>   >   >
>   >   > I think this was not so much a comparison between schooner
and
>   >   una, more between lots of sail and less, although 2 is
definitely
>   >   twice the effort of one. 
>   >   >
>   >   > Apologies for cross posting.
>   >   >
>   >   > regards,
>   >   >
>   >   > rob
>   >   >
>   >
>   >
>   >
>   >
>   >
>   >
>   >
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