Todd,
I just think that Rob is saying that being able to point each rudder independently gives more options. The only one that I can see which might be useful would be to have them both rotate the same direction, for crabbing sideways, but that really just seems like a stunt, and you could always just unhook your linkage if you really needed to do that.
I really like what you have done with the rudders. I have made a mod in my drawings, so that the rudders will tilt based on your direction of travel. I am not sure that the automatic switch in direction when you shunt will work reliably enough, so mine may just be a complication. I have not had a chance to build it yet, but I am planning on trying it. As a side effect, they kick up when hitting something in the water and can also be raised and lowered for shallow water sailing.
The main reason I am interested in tilting the rudders is because of the theoretical prediction of instability in the vertical asymmetric rudder. I have not, however, noticed any indications of that instability in your videos. I am wondering if it only shows up at high speeds. What is the fastest you have ever sailed with those asymmetric rudders and did they ever feel "funny" at the highest speeds?
- Gardner
On Sun, Oct 23, 2011 at 1:00 PM, tsstproa <bitme1234@yahoo.com> wrote:
My boards stay linked I can lift one or the other if necessary , never is necessary.
> On Sun, Oct 23, 2011 at 12:56 PM, tsstproa <bitme1234@...> wrote:
Two smaller boards vs two longer/larger boards each used individually, why bother. When I have one smaller board down I have less wetted surface area down just by way of design so the range is broader than single larger board or double boards down. Linked or not linked, my linked boards still operate just fine with one board up or both down and the pivot up in either direction if hit or while beaching. There's No need to unlink them to use one board.
I have many examples on both my youtube channels. Models and full size craft as proof.
If you haven't at least tried it then you'll have no clue how good it really is!
I'm now thinking of tacking craft having dagger board linked to rudder and counter rotating dagger board pivoting at 50% of its chord. Or the whole board!
Todd
>
> > **
> >
> >
> > Proof I've said to much already . Its up to those who dare to take the leap
> > of faith.
> >
> > To me with the linked set up and sail configuration . There is absolutely
> > no need to unlink for more range . Definitely not to achieve more more
> > control at any speed.
> >
> > Care to expand on what you refer to as more control and range?
> >
> > Sure. Using both rudders to crab sideways and lifting one downwind (and
> upwind in some conditions on some boats) to reduce wetted surface are the
> two that spring to mind.
>
> It is definitely a leap of faith if there is nothing real to back it up. I
> can understand linked rudders in some situations, but cannot see how they
> are going to improve pointing angles to anywhere near as high as 25 degrees.
>
>
> rob
>
> >
> >> > --- In harryproa@yahoogroups.com.au, Rob Denney <harryproa@> wrote:
> > >
> > > Unlinked can be used together or seperately, hence more control and more
> > > options.
> > >
> > > 20-25 of true wind angle at any speed the boat can sail at would be a
> > major
> > > breakthrough (state of the art is about 35). Have you any proof that it
> > can
> > > be done? By proof, I mean gps tracks or sailing alongside another boat.
> > >
> > > regards,
> > >
> > > rob
> > >> > > On Sat, Oct 22, 2011 at 11:49 AM, tsstproa <bitme1234@> wrote:
> > >
> > > > **
> >
> > > >
> > > >
> > > > How does dual unlinked boards give you more control while sailing?
> > Kinda
> > > > sounds like your ranking my chain on this one.
> > > >
> > > > So basically until someones else tells you or shows you what I'm
> > talking
> > > > about in there own words your still in disbelief.
> > > >
> > > > Hey man I gave you an answer on how to sail higher to windward you can
> > keep
> > > > chasing your tail and or follow the herd good luck to you.
> > > >
> > > > With in line linked rudders Like I have shown. You can sail as close as
> > > > 20-25 degrees to true wind at almost any speed the boat is capable of
> > > > sailing .
> > > >
> > > > Its not a matter of ridding and relying on a single aft foil its a
> > matter
> > > > of being able to hold the boat at that heading at any speed and making
> > the
> > > > sail work. Not speed of flow over a single fin/ foil/ or board. Thats
> > the
> > > > benefit of dual linked counter rotating boards. It doesn't require high
> > flow
> > > > rate over boards or a highly crafted foil shape to achieve descent
> > > > performance to windward.
> > > >
> > > > Todd
> > > >
> > > > --- In harryproa@yahoogroups.com.au, "Herb" <squirebug@> wrote:
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Hi Todd,
> > > > >
> > > > > It sounds interesting and I may give it a try next year. I asked the
> > > > group about this a while ago and Rob's view was that dual rudders
> > unlinked
> > > > gives you even more control.
> > > > >
> > > > > At this point I just want to sail closer than 80 degrees to the wind.
> > > > >
> > > > > Best regards
> > > > > Herb
> > > > > --- In harryproa@yahoogroups.com.au, "tsstproa" <bitme1234@> wrote:
> > > > > >
> > > > > > Anyone beside my self ever try?
> > > > > >
> > > > > > If you want absolute control over where your proa heads, you need
> > to
> > > > try it... Or if you want to keep sailing like every other boat for the
> > past
> > > > millennium, don't!!!
> > > > > >
> > > > > > Todd
> > > > > >
> > > > >
> > > >
> > > >
> > > >
> > >
> >
> >
> >
>
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