One of the worst things about GRP are the very nasty splinters that you can pick up in your hands if the mould isn't cleaned up properly...they hurt, they get infectec quickly and they are a real nuisance, so before anything else is done, the whole mould must be trimmed up......I tend to use a power file to trim down toa smooth edge once I have trimmed the edges of the flanges with a jig saw using a diamond tipped blade.
The Flanges then need to be marked for drilling, and drilled with a 6mm hole to take 6mm roofing bolts 30mm in length. Spaced at intervals of around 4" apart, and about half way between the edge of the mould flange and the inner plug the holes are drilled and cleaned up.
Finally the mould is ready for splitting. I start with the Protective belting flanges first, and, using either wooden or nylon V shaped wedges ( NEVER EVER USE CHISELS, SCREWDRIVERS OR ANY STEEL WEDGES)you can generally, with a few taps from a wooden mallet, find a starting point to drive in your first wedge.Just use a little brute force and some physics to drive in wedges along the length of the flange, and as you get towards the middle of the flange, you should hear a lovely satisfying "crack" as the release agent does it's job and the mould parts company from the plug, and you let out a sigh of relief that all the preparation that you have done to the plug has worked it's charm. It really is a great feeling, as the unknown becomes the reality and you find that you have a great mould. Just repeating the process with the second belting flange, progress is now made to split the main parts of the hull. All goes well, and an inspection of the new mould shows that a good moulding can now be taken from the mould.....approximate time to lay up a four piece mould including preparation of the flanges and lay up time .........about 40 hours.