[sailingdog]

Cold molded wood composites like western red cedar/glass/epoxy or strip plank cedar are pretty low maintenance, as are cored composite fiberglass boats like divinylcell/kevlar/vinylester resin... There isn't any one material that is going to stand out.

However, cold-molded wood composites probably have much greater fatigue resistance than do the cored-composite fiberglass materials. A lot of people confuse the two fabrication techniques, since many cored-composite fiberglass laminates use end-grain balsa wood as a core material. From another post on multihulls, I wrote this:

Cold Molded Wood Composite

The first is what Chris White and the Gougeon brothers have done. That is cold-molded laminated wood composite construction. This generally consists of laying up multiple, very thin layers of wood and laminating them together using epoxy. The wood is often finished off by a covering of fiberglass to give it some added durability, but the bulk of the strength is in the cold molded lamination of the wood, not the fiberglass skin, which is effectively just a surface treatment.

Cold-molded wood composite boats tend to be very rigid and fairly light. One major advantage of cold-molded wood composite is the very high fatigue resistance that the wood construction provides. Properly built, these hulls are almost as low maintenance as a fiberglass hull.

Cored Fiberglass Laminate

The second is cored laminate construction. The most common core materials are PVC foams like Divinylcell and Airex, and end-grain balsa, like Contourcore. In this construction, the strength of the material is the fiberglass or composite skins, and the core adds to the strength and lightness of the laminate.

This is not the same thing as the cold-molded wood composite that I mentioned previously—the main difference being the thin veneers of wood used in the previous method are essentially encapsulated and thoroughly saturated in epoxy, which is not the case with cored fiberglass construction—where the resin is only used to bind the skin to the core material, but does not generally saturate the core material.

Highly loaded areas are often given additional strength via the use of carbon fiber or kevlar. The hulls are often given an inner layer of kevlar to increase the puncture resistance.

Many boats can be beached, if you're careful about it...but IMHO, the design of the boat is more important than the materials it is made of with regards to whether it is beachable. Most multihulls can be beached to some degree and many have very shallow drafts that beaching isn't actually necessary. Fin keel or strut and bulb keel type monohulls are probably the worst designs to beach.

Certain things can be done during construction to make a boat more impact resistant. If you're talking about cored-fiberglass composites, using a ductile foam in the hull rather than a rigid one and using layers of kevlar in the laminate both make the hull far more resistant to impacts. Kevlar greatly increases the puncture and abrasion resistance of a fiberglass laminate. It is also, often used to protect vulnerable areas on cold-molded wood composite construction in much the same way.