At my third engineering co-op job, I was presented the opportunity to design a new lifting point for our autonomous underwater glider. The original lift point now had a scientific instrument strapped to the top of it, meaning a new lift point was required.

The lift point would primarily be used during deployment and recovery from the ocean, while on a ship. Having a large ring to make hooking it easier from the ship would be an asset. The attachment point to be used are two screws that extrude from the rounded surface, and a square connector is between them and needs to be avoided. Some initial design sketches can be seen below.

It was requested to be made from 316 stainless steel, which would be corrode sufficiently slowly during the glider’s relatively short missions.

The final design had a top ring, purchased from a commercial seller, then the bottom edge was ground down so that it would have a flat connection with the base part. The bottom piece was waterjet from a block of solid stainless steel, then the two pieces were welded together. To ensure a good connection along the glider profile, the bottom contour of this design was fly-cut. One of the screw holes was also made into a slot so that only one of the holes was locating, and the other floating. These operations were conducted by a local machine shop, and turned out beautifully. See photos of the completed part below.