[Paddlewise] Carving and experiments for that purpose.

Hi Peter,

The concepts I expressed about how carving takes place are based on some 
experiments that I thought I could share with you, and listen to your comments.

If we had planned these as experiments for carving purposes we would not 
have done better. We are working on a water vessel that is absolutely 
unstable. It is a rounded hull with no sharp bow or stern like in a kayak, 
the rounded cross section diminishes as the hull goes to the ends. This 
hull stays balanced using a propeller placed way up front. When in motion 
as you lean and turn the propeller, you restore balance moving in a new 
direction just like in a ground bicycle. You don´t fall as long as you are 
pedalling. This device has been patented.

The point is that in order to keep balance while you rest or while you 
start moving we placed some side wings. So the thing looks like a round 
tube with pencil sharpened edges and a dish on top placed about the mid 
section.  The rider on top of the dish. When in motion, as you lean, one 
side of the floating dish enters the water and gives you few seconds to 
restore your balance  by turning.

WE THOUGHT THAT the wing would place resistance in the water and the boat 
would turn in that direction. We set up the experiment and we found out 
that the turning, very slight, is in the opposite direction just like a 
kayak when you lean. That is if I lean to the right side and the right wing 
touches the water, the boat turns to the left. Just the same as if I was 
raising my left knee in a kayak.

There is no hull asymmetry this time, since the hull cross section  is 
totally round and therefore if you lean, it sees the same shape in the 
water. There is no bow, There is no stern. The only difference from the 
balanced position is that the center of mass is moved to the right and the 
wing, like half a disk, is  in the water on the right side. The wing does 
not have hard surface against the water it grows soflty, and dies soflty.

ANY model that explains carving should be able to explain the behavior of 
this device.

In this device water must move under or around the wing and later on  fill 
the space as the boat passes by. To me the explanation of the turning to 
the left has to do with the fact that water resists to the passage of the wing:

1.- In front of the wing water accumulates and must be displaced and it 
pushes in all directions, including pushing the front hull to the left.
2.- Behind the wing, water must come in to fill the space left by the wing 
and therefore pressure there is lower. The pressure on the left of the hull 
is larger than on the right of the hull behind the wing, and therefore the 
stern is pushed  to the right.

The final motion is a turn to the left.

We did that time after time with different geometries, because we wanted to 
achieve the opposite effect.

We pulled the hull with a string from a long distance to make sure to have 
an even pull and then  the rider leaned to the right. Always the effect was 
that the boat moved to the left or in the worst cases to continue straight 
(one out of 20).

SO MY CONCLUSION IS that  when you lean on a kayak the widening of the mid 
kayak on the right side and shortening on the left has more effect in the 
carving than other matters. If you add a stern that moves to the left of 
the line of motion the effect may be enhanced, and finally if the bow sees 
water coming on the side once it started to turn, then you get the most of it.

Having this device at hand I can repeat any test or modify it to suit any 
request and report the results.

Best Regards,

Rafael
www.mayanseas.com





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