Most boats have cast iron or lead keels attached to the reinforced plastic hulls with stainless steel studs that protrude through the hull and are exposed on the inside. On assembly of the new boat the load is transferred to the hull with thick square or rectangular stainless steel plate washers clamped down with stainless steel nuts. Every few years it is good maintenance practice to check the connection and re-torque the fasteners.
On a CS33 the keel can weight up tp 4500 lbs. and the attachment is two 3/4 diameter studs, one forward and one aft and and eight 7/8 diameter studs spaced over the remaining area. One of the forward studs may be double nutted with the top nut to secure the grounding strap from the mast/mast step.
Most boats with suspended keels will have a somewhat similar arrangement that is scaled up or down depending on boat size and weight.
First Checking: A good cleaning is in order and the stainless parts checked for rust stains. Under ideal conditions where the bilge is dry and clean most of the time the stainless steel that is exposed should be shining. If a rust film is evident and the rust film can be removed easily there is little concern. The rust film is a product of stainless steel corrosion when Oxygen (air) is excluded from the surface of the Stainless steel. A dry clean bilge is important. Next check under every washer for any sign of compression of the hull material. If the stainless parts have deep set corrosion, or the hull material has compressed in any way, or if the hull structure shows any sign of structural failure a marine survey is required to properly assess corrective action.
Now Retorquing: The tools required are a bit larger than normal but a well equipped heavy equipment mechanic is your best source. Again the larger the boat the larger the tools and the harder to source. For the CS33 deep wall 12 point sockets sizes 1 1/8 and 1 5/16, a short extension, a powerbar (to remove double nut), torque wrench to 300 foot lbs. and strong arms are a must.The top photo is the setup for retorquing the 7/8 diameter nuts to 200 foot lbs and all nuts (8) turned 45 to 90 degrees. The right photo is retorquing the most forward 3/4 diameter nut to 175 foot lbs. and this nut turned approximately 180 degrees. The aft 3/4 nut turned 60 degrees. The final result was a clean bilge and confidence that the hull-keel join is secure and all studs/nuts are evenly torqued.