Chine development

[MikeJohns]

Originally Posted by Wayne Grabow

Considering the drag associated with chines parallel to the waterplane versus sweeping upward toward the sheer; if the hull experiences pitch, such as in waves, the parallel chine may have greater drag due to vertical motion of plunging into then withdrawing from the water surface........

Design for least drag at the chosen operational speed. You'll find that studies on chines don't support what you've suggested above. For example vessels with completely flat sections forward can have an advantage over a V'd foresection because of their high pitch damping, providing the flat is deep enough not to slam.

Sweeping the chines up forward is nearly always detrimental to smooth water flow and trips the flow and produces a visible wave pattern at the chine waterplane intersect. The continuous longitudinal flow has far more effect on drag than periodic transient vertical turbulence.

Experiments have clearly shown that carefully placed chines reduce the total resistance over even round bilge forms, but the rules are that you sweep the chines with the flow field at the design speed and keep the exit waterplane intersect chine angle shallow. Sweeping the chines up forward was always detrimental.

A sailboat designer has to consider the heeled windward condition as well.

But the usual proviso is that if you are designing a heavy boat that will operate at low Froude numbers then it's not going to make much noticeable difference in a seaway whatever you do