estimating displacement

[dionysis]

hi all,

I am looking for a quick (default) way to estimate displacement using prismatic coefficient, waterline length, beam and canoe draught, without having to apply Simpson's Rule.

As a first approximation : ~0.7*beam*draught*lwl*Cp?

dionysis

[nico]

Cp= Disp/(Lwl*Am) Am is max section area
Cm=Am/(B*T)

Disp=Cp*Lwl*Cm*B*T

For a sailing boat 0.65 = Cm should be good

It is probably easier for you to caculate Cm from your design

Cm=Max section area / (Draught*Beam)

This only an approximation ( says that beam and depth are max at the same section )

Nico

[dionysis]

The idea is to develop a program which can take default values for waterplane area, displacement etc from initial measures of length, beam, draught, ballast ratio, sail area etc and then go on to calculate comparative vpp's.

I will be able to compare narrow boats against wide boats, heavy boats against light ones, without needing to generate detailed drawings.

I suppose this is what most designers do when exploring different configurations before settling down to a detailed study of their chosen design.

Next step is to work out what the influence of heel has on drag, then settle down to working out stablity algorithms...

I wish I had more time for this...it's great fun!

thanks again nico

dionysis