Bureaucrat, staff, administrator
4,335
edits
Changes
m
→References
* Non-cross-linked or "linear" PVC (L PVC) e.g., Airex® R63, is used in the same areas as SAN.
* Polyurethane (PUR) and polyisocyanurate (PIR) foam are used in acoustical and insulation panels, structural insulation panels (SIP) and parts like stringers.<ref>Foam Core Materials in the Marine Industry, Trevor Gundberg, Composite Materials Engineer, DIAB Inc., BoatDesign, http://www.boatdesign.net/articles/foam-core/</ref> These foams are water resistant, meaning they will absorb some water, around 5%, and encourage mildew.
NIDA, an extruded polypropylene honeycomb covered in polyester, is in a class by itself. It is an extremely strong core material. Divinycell (diab core) is an inter-penetrating network (IPN) of PUR and PVC.
A honeycombed core such as over-expanded Nomex can be used in dinghies to reduce weight. Honeycomb is not suited to a displacement hull.
Where cost is not a consideration, aramid and carbon fibres can be used to reinforce fibreglass. Aramid<ref>Fibresource, http://www.fibersource.com/f-tutor/aramid.htm</ref> is a family of manufactured nylon fibres, including Kevlar®, Nomex® and Twaron, based on long-chain synthetic polyamides. Kevlar® has been used in some small-equipment applications like paddles and in high-speed boat hulls for the US Navy SEALS.
<ref>E. I. du Pont de Nemours and Company, http://www.dupont.com/kevlar/</ref> <ref>New boat aims to make SEALs' travels less painful, CNN, http://www.cnn.com/2008/TECH/01/13/seals.new.boat.ap/index.html</ref> In trawlers, the Krogen 58 has Kevlar-reinforced bottoms in the stem and stern areas.
A similar technology is carbon-fibre composites. These are generally too expensive (and too light) for displacement boat hulls but are found widely today in aircraft and automotive parts like wing assemblies, monocoques and body panels where strength and light weight are important,<ref>DPS Composites, http://www.dpscomposites.com/</ref> or in super yachts like the aforementioned Juan K Super Maxi. The Maxi is a high-speed sail boat, not a displacement boat, so light weight is important.
== References ==