the resistence to movement of a displacement hull goes up with the square or
speed, and the horsepower needed goes up with the cube of speed.

so, in more or less correct terms, doubling the speed of a displacement hull
requires about 8x the power.

Does anybody know what relation there is between fuel consumption of a
displacement hull and its speed?
Is this linear, quadratic or something else? To make it more concrete,
say you have a consumption of 60l/h at cruising speed. Would you then
e.g. see 30l/h at half the cruising speed and 15l/h at 1/4th the
cruising speed or would it be more, or less?

TIA, if you prefer (also) email amulder(AT)rootshell.be