This produces a near-perfect surface finish, but is more expensive and difficult to make. A mold-release agent is typically used to ensure the product can be removed easily.
Northstar was built from a custom, professionally made mold. A male plug was milled from MDF, prepared by the team, and sent to a company who constructed the female mold. At least two hulls were taken from these molds, and as off 2011 they are still in perfect shape, ready for use again.
The 2010/2011 hull will be built from a CNC milled female mold. No male plug is involved. By building the mold billet and hand-cutting out profiles every 2", machining time can be reduced to that of a male plug, saving the step of pulling a female mold off a male plug. The mold will be prepared using West-System Epoxy , to ensure good surface finish.
This process is simple, but results in asymmetry and poor surface finish, especially with complicated layups.
The 4m was constructed over hand-shaped profiles. The hull is symmetrical and well shaped, but the outer surface is poor, and will need considerable fairing. As well, the layup was not vaccuum-bagged, so there is considerable extra weight.
In 2010, Gaelforce was built over a CNC milled male plug. The hull was vaccuum bagged, but the complicated layup (involving laminating and fairing expoxy, as well as three kinds of fabric and a foam core) led to slippage and poor outside surface shape.