Fixing the position of the Blind Date rudders is one of those details that are not working as they should. The steering lines run through clamcleats. Sometimes they slip. When the helmsman forgets that a rudder is fixed and uses force, the lines are very hard to release from the clamcleats.
I am thinking of a way to fix the rudder in only one position: the exact correct angle for the back rudder for sailing up wind.
I see no need for fixation in any other angle at any time.
The most logical place to fix the rudder position is on the disk of the rudders, not somewhere on the lines.
When the helmsman tries to steer, (tension on the steering lines) the rudder should be unfixed automatically (like cruise control on a car).
In the YouTube movie (http://www.youtube.com/watch?v=bu50OUfz63o) the Blind Date helmsman holds both rudders because that is a good way to learn to feel the ship. It feels right when the hulls go straight through the water and the rudders prevent drifting.
You can feel the rudders doing some work when they are in the optimal angle.
You can even hear that the sound of the water is different when the rudders are in their best position.
It takes some time and a lot of practice before your reflexes work well for both rudders.
Theoretically it is probably best to steer with the front rudder.
Using the back rudder as a daggerboard means that the COE (sail force) is straight above the lateral point.
Steering with the back rudder works like the way a Hobie 16 catamaran works. The hulls of the Hobie 16 were designed to prevent drifting, making a daggerboard superfluous. These hulls can be described as a compromise between a hull and a daggerboard. In races we noticed that trimming the mast as far backward as possible gives the best upwind performance. This way of trimming brings the COE to the back, so the rudders work like daggerboards. Their aspect ratio makes them much more efficient (lift/drag) than the hulls. As long as you sail a Hobie 16 in a straight line as much as you can, there is nothing wrong with using the rudders as daggerboards. 'No unnecessary steering' is the key for speed. The best way to steer is using the sails or moving the weight of the crew.
On recumbent bikes (and other bikes) many inventors have tried steering with the back wheel. It was never successful because of lack of control. The same goes for cars. Steering with the back wheels makes a car very unstable, especially at high speed.
Birds and fish on the other hand use their tail for steering. In the air and in the water stability works the other way.
On the Blind Date we noticed that it does not make much difference what rudder we use. Steering with the front rudder feels more delicate when sailing into the wind. On down wind courses steering with the back rudder seems to give the helmsman a little more control.
It is fun to play, steering with both rudders. You can make the boat go sideways or make it (almost) stop within 10 seconds. Pulling the hand brake like that is also a good way of testing the strength of the rudder blades and the rudder lines....
Nol
--- In harryproa@yahoogroups.com.au, "LucD" <lucjdekeyser@...> wrote:
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> This is a very interesting discussion. Keeping the original vessel's mission straight in the mind keeps misunderstandings to a minimum.
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> There is (at least) one point that I am still confused about. Was the standard operating procedure to steer with the front rudder or is this the result of on the water trial and error? (like kangaroo hopping became the preferred mode of biped locomotion on the moon) It looks a bit funny to see in the last BD video the steerman grab the front steering wheel to steer with his arms reaching over the back steering wheel that remains fixed. Was this by design?
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