Question By: Tom Lipovits
I would like to hear opinions on which bulb shape would be best to use on a model boat. I've seen round (cross-sections),
squarish, ones like older 12-meter boats use with the heavy wings, and exaggerated bulbs, like the stars and stripes
from Victor models. I even read about the keel bulb with the plastic wings as in Radio Control Boat and Modeler.
I like one with a round forward section, and a flatter aft section.
Answer By: Anthony B. Payne
A round cross-section with a length/diameter ration of 4-7 is good. The shorter one has less wetted area, the
longer one less form drag, as to the best cross-sectional area? Theoretically, elliptical with the major axis at
right angles to the keel gives best lift/drag ration to keel, and gets the weight lowest (when it's restricted)
but … it has more wetted area than a circular section. All these differences are probably very small at model
Reynold's numbers. It is very doubtful if winged keels would work, but I can give you lot's of details about
it if you wish.