It is suggested for ease of handling that while you can prepare the ballast at anytime, installing the primary ballast permanently should be after operations that require upsetting the hull.
There are one primary ballast and two removable. The primary is glued into the hull and can either be supplied with the hull or poured by yourself. The one shown below was poured in the #1 sacrificial hull. The other two were made from sand castings from the first boat built. The numbers below could be of some help for pouring in your hull. (2011: Hulls and casted ballast from molds are available now at CPM in Maryland.
Primary: Installed at station 38.75 and glued in. This is 8-1/4" long at the top and 3-1/2" deep at the aft end. The one shown above is not trimmed. Weight is 13.24 pounds.
Center: This piece is trimmed to snug up to the primary at about station 44. This is 8-5/8" long at the top and 3" x 5-1/4" tall. Weight is 25.6 pounds with the handle.
Aft: This is snug to the center piece at about station 53. This is 7-3/8" long at the top and 4-7/8" x 4" tall. Weight is 19 pounds with the handle.
While this weight is almost 58 pounds, there will no doubt be some trimming weight added when the boat is completed and in the water. When the work surrounding the compression strut tower is complete and the radio gear fitted, glue in the primary ballast.