Scaling up a structure or everthing I know is wrong

I just got back from hoisting my 1800 lb daggerboard to add another block so that I might get more mechanical advantage so that I don't have a heart attack every time I want to hoist it. Thus inspired I thought I would pursue, some more, the idea of replacing it with an 1100 lb bulb on a fin that would give me the same righting moment. Now the simple way would be to hire someone with the expertise to design said fin. Never being one to do it simple, I was thinking about making a sixth scale model with a 200lb load on the end and scaling it up. So I went to the shop and ripped two pieces of cedar, one exactly half the dimensions in all directions of the other. I had them span their length and measured the deflection when the shorter one had a load and the doubled one had twice the load. To my surprise they both deflected the same amount +/- a tiny little bit. I expected the longer one to deflect more but instead the longer one had half the deflection as a percentage of length. Obviously I am no engineer, though I do look like one. Actually I teach high school physics, I am no physicist either, but what little my textbook says about scaling, my experiment contadicts.
So I have two questions; first is it possible to use a scale model to design the layup schedule for my keel and second what am I not getting about my simple experiment. Thanks Todd Miller

The picture is of my boat I designed and built.

 

Todd,
Don't forget that the larger one, if exactly twice the dimensions, will have 8 times the inertia of the smaller one. On a simply supported beam, half the distance should (IIRC) give 1/4 the load, and half the weight should make it 1/8th, so the same deflection is right
Steve "or something like that...."