First. I hypothesize that chinerunners work as deflectors, not as hydrofoils. Deflectors are concave surfaces that redirect what hits them. According to Newtons third law the more water the chine runner deflects to lee the more the boat gets pushed to windward. When the boat is heeled, the hullside together with the chinerunners creates a lot of lateral area. Unlike the ordinary keel I think the Bernoulli effect plays no significeint role here. This may explain the chinerunners remarkable efficiency and why they are so misunderstood.
Second like bilgekeels they protect the boats bottom at low tide.
Third they let me put the lead ballast a bit lower.
Forth they keep the lateral resistance high up those decreasing the heeling moment. Everyone realizes that a sail center high up heels the boat more than a low one. Not every one realizes that a lateral area high up heels a boat more than a lateral area deeper down.
Fifth the chinerunners reduces rolling.
Sixt It is likely that they prevent that turbulence a nd vortices are created along the chines thus reducing resistance.
Seventh. As the boat heels so much that the windward chinerunner lifts out of water the volyme of the windward chinerummers now mowes to lee and becomes boyancy in the lee side thuse creating extra rightning moment kind of like a submerged trimaran that lifts its windward float. The effect is not big but it helps.
Its the combined advantages of the many small advantages that makes me chose them. If at all time you can increase your efficiency even by a small bit, in the end you be doing good.
To be continued…
Regards Yrvind.