The drag coefficient is a function of several parameters like shape of the body, Reynolds Number for the flow, Froude number, Mach Number and Roughness of the Surface. Skin friction is based on the friction between the water and the shell. Those things are very hard to express mathematically, so the usual approach is empirical.

The drag critically depends on the shape and the surface roughness. The drag coefficient of any object comprises the effects of the two basic contributors to fluid dynamic drag: skin friction and form drag.

There is a frictional drag that is given by the shear due to the viscosity. Objects drag coefficients are mostly results of experiments. The drag coefficient of a lifting airfoil or hydrofoil also includes the effects of lift-induced drag. When paddling in water less than maybe 6 feet in depth, there is a very noticeable increase in drag, which increases as the depth decreases.

This can result in 50% of the total resistance in fast ship designs and 80% of the total resistance in slower ship designs. This formula can be written as Cp = Ï /Am x L

The characteristic frontal area - A - depends on the body.

A thin film of water is accelerated to the …

This is true for all the types of boats I paddle, from a large 6-person Hawaiian outrigger canoe (L=40', width=2', draft=0.67') to a … I'll try some searches to see if they have any standard data.

The timber industry has a long history of pulling logs in the water. The prismatic coefficient (Cp) is the underwater area, divided by the area of a midship section, times the length of the ship. Form drag is a force proportional to the square of the boat speed that depends on a drag coefficient which incorporates area of the shell and density of water.

It is an indication of hull fineness, and may be broken down into fore & aft components. The tug boat industry has a long history of pulling barges. The drag coefficient is always associated with a particular surface area.