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Design of the Scow 450
The main characteristic of river boats is their flat bottom,
and so for a very light draught allows a large loading capacity. Flat surfaces are not intended for choppy waters,
there tend to slam and loose speed even in a moderate
gale. As I planned an extended cruise, it would need a
cozy cabin was, with space for living aboard , meaning
eating a hot meal, sleeping for the whole crew, and toilet
facilities. So I decided to build a very simple but radical
boat, with a square plan and section, no cockpit, and a
very large cabin for her size.
My first design challenge was to draw a bottom rocker
that comprises of a fine entry, a long waterline, within
the bending limits of plywood. The theory says that for a
good pressure distribution there must be no straight section, the curvature needs to be well distributed.
For the structural aspect, a curved surface has more stiffness
that a flat plane. So as a compromise, I draw an entry curve
that should follows the curve of moderate waves, a very short
strait section in the central section, and a transom high above
the water.
The length of the boat was first set to 5 meters, but
it rapidly seemed that it would end up too heavy boat
and, as I am not a Rambo, I must be able to take it
off the water and haul on the trailer without taking steroids. As a standard plywood sheet is 2.44 m long, I
found it logical to divide this length in two, minus the
butt join part, and end up with a 4.5m boat.
Another crucial point was the trailer cost, in the 4/5
meters range there are a lot of suitable basic trailers
available, beyond you enter the “nautical market” ones
that are much more expensive.
One challenge was to minimise the off-cuts, and use as
much of the plywood as possible from each sheet, as the
project was on a very tight budget.
Building the “Norwegian Wood”
It took me almost a year to draw and precut all the plywood parts in my barn. As the door is narrow, the final assembly was planned outside. For the absolute beginner I was, the most difficult part was to bend the solid wood
stringers, I used both boiling water and kerfing at 1/3 of the thickness on the most curved sections of the roof.