Interference Factor

[navarch_hish]

I am designing a high speed catamran ferry. 35knots speed..

I am doing the resistance part of the project and i need data regarding the intereference factors..

Viscous interference factor
Wave intereference factor


Can anyone tell me on what factors these depends on and can somone provide me some graphs from which i can interpolate to find the intereference factors suitbale for my vessel

My vessel Details
LOA = 49.4
Bship= 13.2
bhull = 3.17
D = 4.32
T = 1.72
CB = .625
LCB = 6.2% aft of midship

Give ur comments on my ship

[marshmat]

Hi navarch,
It sounds like this is a school assignment. Do you have any textbooks handy?
I'm curious as to what you mean by "interference factor". Are you trying to figure out how much drag is due to the interference of the wakes of the two hulls? That's virtually all due to waves... the (viscous) boundary layers of a cat's two hulls don't usually meet each other.

[Tim B]

Have a look at the work by A.F. Molland (et al.) from Southampton University (UK). A lot of tank testing was done and the findings are well presented. This should answer your question.

Tim B.

[tspeer]

If the hulls are symmetric and carrying no side force, you can compute the wave interference using Michlet.

For some experimental data on asymmetrical hulls, see
Papanikolaou, et al, "Hydrodynamic Optimization of Fast-Displacement Catamarans", Twenty-First Symposium on Naval Hydrodynamics (1997), The National Academies Press, http://darwin.nap.edu/books/0309058791/html/697.html.