Swinging Keel Strut:
Developed for use on a proposed prototype
for a new Olympic Class racing keelboat, this swinging keel strut was designed
to support a 450 lb. keel with a highly stressed bending load induced by the
process of winching the keel to windward on upwind legs, so as to give the boat
more resistance to healing, and thus allowing greater thrust from the sailplan
and higher speeds upwind. The spud at one end with the 2 holes fits into the
streamlined lead keel. The integrally machined keel strut pivots are visible
about 2/3 of the way up the strut, and the clevis fork at the far end accepts
the hardware used to swing the assembly. The strut is about 6 feet tip to tip.
The last 2 pictures show the 6061-T6 plate stock fixtured to the vertical
machining center with the strut in-process. The hydrodynamic surface up to the
pivots is a NACA low drag airfoil section with a tapered planform and variable thickness
distribution, which was hand finished to better than a 32 mico inch finish.