: You can scale all dimensions linearly. Just have to remember the
: volume change will be cubic.

: Example:
: Take a sea kayak that is 18' long x 21" wide with a design
: displacement of 250 pounds.
: Now scale it down 20% (80% of full-size).
: The new dimensions are 14.4' long x 16.8" wide.
: The design displacement is about 1/2 though. It drops to128 lbs
: (250 lb*80%*0.80%*0.8).
: Could be a boat for an advanced child paddler.

: =D
That works for a model test, but won't yield a very useful boat. There are a few ways to change the parameters such that the design will still work.