Here's another calculator from the discussion
over at rec.boats.building. It makes a simple hull
drawing you can view by moving your mouse.
<a href= target=new></a><br><br>It gives the force in pounds required to drive your
inputted hull to the speed shown on the chart. It
calculated the fore & after bodies separately then adds
them. It also calculates the skin friction and wave
friction separtely then adds them. Dividing this force by
70 will get you the approx Hp required.
<br><br>There are six inputs, the first three are obvious:
Length (waterline), Beam (waterline) and Displacement.
CP is the Prismatic Coefficient for the entire boat,
CP1 is for the forebody only. (the calculator then
figures out what the afterbody is from the ratio between
CP and CP1) Maximum speed is really just "how far
out do you want the calculator to show the results."
For an easier to read chart, keep this just a tad
greater than your anticipated top speed. Results are good
only for hulls with fine fore and after bodies. Making
the boat look like a planing hull will give you false
readings, it assumes you are making a displacement boat
only. It looks like it might work correctly as you go
towards semi-displacements.<br><br>For a canoe begin with
these six inputs:<br>16'-2.5'-400#-0.5-0.5-7<br><br>For
a 5:1 hull you might see on an electric cruiser
try: 30'-6'-3000#-0.65-0.60--12 Watch the results as
you vary CP1 from 0.65(symmetrical displacement) to
0.60(assymetrical displacement) to
0.5(semi-displacement)<br><br>Lots of hydrostatics given below the chart. Comments?
