The P26 keel is external cast iron and weighs about 2,200 pounds. The keel is swept back approximately 50 degrees from vertical and has a chord length (leading edge to trailing edge) of about 66" at the top and 51" at the bottom. The maximum chord thickness varies from about 4.2" at the top to 5.1" at the bottom. This is probably to concentrate ballast. The bottom of the keel is V shaped. The keel is swept back about 50 degrees from vertical and has an area of about 13.2sf(one side). The top flange of the keel is about 5/8" thick and fits up into a socket in the bottom of the hull.
The P26 keel is attached to the hull with eight 5/8 x 3-1/2" 11-TPI ( Threads Per Inch) flat head bolts. The bolts fit from holes in the top flange of the cast iron keel up through the bottom of the hull. The holes in the keel are filled over after the keel is installed. In a letter to the Pearson Current (newsletter of the NPYOA) Bill Shaw gave a torque spec of 70 lb-ft for the 5/8" keel bolts.McMaster-Carr has what look to be suitable replacement bolts, washers and nuts. The part numbers are:91253A808 5/8-11 3-1/2" flat head bolts
95479A125 or 93827A253 5/8-11 nuts
98099A035 or 98025A035 washers (thick and large)
McMaster-Carr web site - Plug these part numbers into the search window.
The hull is cored with plywood in the keel mounting area. Pearson cut 2-1/2" holes through the glass/plywood layup and filled these holes with a mix of glass and resin. Through this they drilled the holes that receive the keel bolts. The keel bolts are backed with washers and fastened with nuts.