Re: Why superships cost more per mass

On Fri, 29 June 2001, David Griffin wrote:

> I don't know much about the Canadian navy, but if
> they were working on a class of ship they're used
> to working on, and they weren't trying to do anything
> they hadn't done before, then I don't think size
> would have that much to do with their overruns.

Even if you have a robotic ship building facility, complexity still
increases with size, and as Tom pointed out it isn't linear.

As the ship gets bigger, you have more "connectors" (whether it be
points where load bearing members connect and have to be welded, or
points where wires/fibres connect, or weapon mounts, what have you). You
have more of them, because your ship is bigger. Each one of these is a
potential point of failure. If you have 10 connectors in a destroyer and
100 connectors, you have 10 times the number of failure points in the
larger ship. The larger ship will likely have 10 times the failures of
these parts.

However, there is a cascade relationship happening. One part breaks
down, resulting in stresses on other parts. This cascading effect is
worse in the big ship, and is the reason the complexity isn't linear.

Anyone in engineering, or in programming, knows this. A 500,000 line
program is more than 10 times more prone to failure than a 50,000 line
program.

Now, throw into the mix the fact that other people are TRYING to make
these things break. They are warships, after all.

Even if building them is automated, a bigger ship will be more complex
than a smaller ship, and more than just in proportion to the size
difference.

Allan Goodall - agoodall@canada.com
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