Friction has not been a problem at all on our boat. I think some
friction is a benefit. Maybe in future the upper ring might need a
replacement because of wear. There is some black plastic powder visible
under upper collar isinde the hull.
My friend has a boat similar to this:http://dobrakusa.blogspot.com/
The balls are fromm forties and it still works.
Regards,
Arttu
>
> Has anyone tried some ball bearings under the mast to reduce friction?
>
> Best regards,
> Herb
>
> --- In harryproa@yahoogroups.com.au, Doug Haines <doha720@...> wrote:
> >
> > Hi Nol, Could you explain a little bit more about your position in
the BD team.I know Rudolph is the builder. Who is usually out on the
boat most of the times?Does someone get to choose the destination and
really - who is the captain onboard? I am the only one who really has
ever sailed on SIdecar and I don't have much conversation on the
sailing. Mostly with Rob. I think we agreed that the jib is not a
"tight" shape and goes saggy. I didn't like to use that jib and it
didn't seem as safe as the previous rig. Also I would like to add that
I also found that I wanted the extra saftey factor of releasing the
sheets and allowing it to luff. This is easy with main only but not
responsive enough when the jib is up too.I though that maybe I had too
much friction in the mast bearings, but perhaps that is more common on
other aerorigs too. DougPerth
> >
> > --- On Thu, 18/8/11, Nol Twigt <noltwigt@...> wrote:
> >
> > From: Nol Twigt <noltwigt@...>
> > Subject: [harryproa] My problems with the aero rig on the Blind Date
> > To: harryproa@yahoogroups.com.au
> > Date: Thursday, 18 August, 2011, 6:04
> >
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> > Let's start with advantages:
> > There is not much power on the sheet. That makes the rig very simple
and very easy to handle.
> > It is a self tacking system. Not much work when tacking. Shunting
requires more power, however it is also kind of easy.
> >
> >
> > I have whole list of disadvantages from all sort of angles.
> > The main thing is simply a matter of control. We have lots of
shallow waters int the Netherlands. If you want to sail on the Waddenzee
for example, you need to be able to sail with the rudders (almost)
pulled up. This is impossible with an easy rig that is positioned in the
middle of the leeward hull. End of story.
> >
> >
> > Now let's look at the aero rig from other angles.
> > Let me start with a matter of taste, so my cards are open on the table.
> >
> >
> > Subjective arguments:
> > - I do not like the way an easy rig looks. It does not look
'aerodynamically right'. Usually if things do not look fast they are not
fast.
> > - It looks kind of unnatural because it seems to be lifted from the
ship. It is not one with the ship.
> > - The look and feel is kind of lazy. Not interested, taking things
too easy. Statical, almost dead.
> >
> >
> > Mechanical arguments:
> > - The strongest forces are the vertical forces on the forestay and
the leech of the mainsail. These enormous forces are countered by a boom
that must be very strong and will be very heavy. This is not an elegant
solution. It is brute force.
> >
> >
> > Sailors arguments
> > - On the Blind Date the boom connected to the mast with a hinge. The
result is that you can not trim the mainsail and the jib independently.
You want much tension on the luff of the jib and little tension on the
leech of the main. The topping lift could solve that problem, but that
does not work on both bows. Two topping lifts would be better, but that
would mean an extra line to take care of after every shunt. It would
make it an a little less easy rig.
> > - You can not sheet the mainsail and the jib independently. You can
not steer the ship with the sails. You can not play with the waves and
the sails.
> > - There are situations where you want to let go the mainsail without
changing the jib. For instance when you are overpowered in a gust. In
strong winds the mast has so much friction that it does not turn when
the sheet is released. Not safe.
> >
> >
> > Applied on a proa (controlling and steering the ship with the sails)
> > The COE (Center of Effort) is behind the mast. This is necessary to
get some power on the sheet and to make the rig turn when the sheet is
released. The result is momentum 1 that makes the ship want to turn its
nose into the wind.
> > The mast is placed on the leeward hull. The COE is on the leeward
side of the ship. The result is momentum 2 that makes the ship want to
turn its nose into the wind.
> > Momentum 1 + momentum 2 make the ship by definition out of balance.
> > The balance can only be restored by using big strong rudders. The
back rudder is used as a daggerboard.
> > This is again countering enormous forces with other brute forces:
not elegant.
> > In shallow waters, when you need to pull the rudders up, the ship
will be out of control. Momentum 1 + 2 are not countered anymore. The
ship will turn it's nose into the wind.
> >
> >
> > Applied on the Visionarry proa's
> > Visionarry looks modern, light, fast, like a flying saucer or a
fighter plane, hi-tech.
> > The aero rig looks old fashioned, slow, low-tech.
> > On a light ship that is built for speed, control is a crucial
factor. The aero rig is static and does not contribute to the control of
the ship. It needs extra control for it self.
> >
>
>