A word about the keels and skegs on sailboat hull moulds.   You should attach the keel frames to the hull frames by screwing - do this in a way that allows you to unscrew the keel section before removing the mould.  Sometimes the keel will be reluctant to part from the mould so by making provision to allow the hull mould to be removed without the keel section, you will overcome this potential problem.   Skegs can also be built separately and attached to the mould with a screwed gusset as the same problem may arise.