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Somewhere 1500 and above is a good score. 1st place usually takes somewhere above 2500 in our state, but our last invitational 1st place bridge was above 3200.
At regionals, our bridge won at 3600.

How much weight are your bridges holding?

3600 That's impressive!!!
I had state 2 weeks ago and I won with a 1655 efficiency but I just got 2409 today. I expect someone at nationals to get in the 3000's for Division C.

In CA a bridge with 2400 would be lucky to be in the top 10 at state for division C.

Be careful comparing across divisions. Often the competitive efficiencies are quite a bit different in B and C.

This is my schools first year in the SO and my bridges keep maxin out at about 1000 efficiency in the division B 2015 rules. Could somebody please give me some tips to raise the efficiency. Your help is greatly appreciated thanks

1. Is there any way you can reduce the weight of your structure without compromising the structural integrity? There are several ways to explore this:
a. Last year and this year, teams used 1/4 in by 1/4 in balsa sticks excessively for their structures. Can you use pieces with smaller (and lighter) dimensions?
b. As a followup, can you use pieces with smaller densities? Even if pieces have the same dimensions, they will have different weight possibly.
c. Consider also sanding a structure carefully or air drying the structure to knock off weight due to moisture.
d. Bracing. Will a Z-bracing work over an X-bracing? (you can possibly remove some pieces from the design and thus weight)
e. Glue. This is one of the biggest source of unnecessary weight. You don't need to apply a lot.

2. The way you load.
a. Some teams have the sand hit their hands first to reduce the force of the sand upon impact with the bucket. They usually increase their score by a couple ten's of a point.
b. It doesn't matter if the sand is level within the bucket. But do not load in such a way as to make the bucket sway. This introduces different directional forces to the bridge.
c. Consider placing the loading block in different locations.

3. Design Changes
a. Have you tried using gussets? Don't underestimate the value of them in certain locations.


If I think of something more, I'll tell you. This all said, the biggest help you can do for yourself is research. That's how the best teams did it. That's how we did it.

9Fire wrote:This is my schools first year in the SO and my bridges keep maxin out at about 1000 efficiency in the division B 2015 rules. Could somebody please give me some tips to raise the efficiency. Your help is greatly appreciated thanks

If you could give some specific information about your bridges, we could help out more. What basic design and wood dimensions are you using? What mass is the bridge and what weight does it hold? I think selecting good light wood could help. Measure the masses of each stick before you use them and make sure they are approximately the same.

The wood is usually 1/8" or 1/16", usually the bridges are arch bridges with a warren truss and x bracing on top, which we migh change to z bracing to help save weight. We also load on the top usually.

I never thought of weighing each piece, good idea thanks