Thanks, Don. Some semantics involved here I am sure. I am more familiar with engineering terms than nautical terms, but we consider COG and balance points to be synonyms. While both are a point in 3d space, I am only concerned about the fore/aft COG location (port/starboard is assumed to be centerline, vertical is not an issue for my use case). For the H40, the hull-keel interface is about 11'-8" long, at each end of this the keel slopes about 45 degrees up and away from the center of the boat. This has the effect of quite accurately locating the slings when lifting the boat on the travelift (they slide up the keel to the keel hull interface). Modern travelifts can report the weight supported by each of the slings. So if you know the precise sling location and the weight on each of the slings, then you can quite simply calculate the fore/aft COG of the boat. Therefore, if anyone here has a H40 that is going to be on a travelift anytime soon, please let me know.
Thanks!