With several decades of experience aluminium is now regarded in the marine industry as the choice material for high seas vessel hull construction. Its exceptional lightness, rigidity, resistance to puncture, and durability translate for the owner sailor in performance, lower cost of ownership, and above all higher security. An aluminium hull does give the investment in a high seas pleasure vessel a lot of sense.
Why aluminum for boat building?
Strength to weight ratio – Aluminum has superior strength to weight ratio which allows for building stronger and stiffer boats while keeping them light for performance. Aluminum sail yacht construction exhibits 50-60% weight savings for equivalent strength and stiffness compared with steel vessel. Aluminum lends stiff and fast hulls.
Resistance to puncture in sudden impact – It has been shown that a strength-equivalent aluminum hull boasts about 29 percent greater dent resistance and 12.5 percent greater resistance to rupture than a steel one, due to the ductile nature of aluminum. The comparison to plastic or fiberglass is not even discussed. Resistance to puncture due to sudden impacts with containers is crucial for safety at sea, and a metal hull is often the only reasonable safety choice for ocean going vessels.
Stories of aluminum boats stranded on rocks or coral for days, absorbing blow after blow against their hull, denting —but not rupturing— and being towed to a yard where their damaged sections are cut away and replaced are not uncommon. In such instances, a fiberglass or plastic boat would be totally damaged and lost in a matter of couple hours.
Durability – Marine aluminum is low maintenance and extremely durable. It will not rot, soften, loose its strength properties, suffer delaminating, blistering, leaks, and problems associated with structural fatigue or decay with time. It can be painted or left bare at the owner’s choice. If unpainted, it will build a protective “patine”, and can be polished once in a while anywhere in the world at low cost. High end paint finish will last and keep its looks for many years, and should it be redone, it can be at reasonable cost. The repair of an aluminum vessel does not pose any specific problems can be done in many places of the world.
Fire protection – In case of fire, aluminum does not burn in air nor will it support combustion. In several tests, aluminum received the highest ratings for resisting flame spread, not being ignitable under atmospheric conditions, and not supporting flame spread. Fire resistance is the second element of safety at sea after resistance to puncture.
What about corrosion? Aluminum has been used in the marine industry for decades has shown very good corrosion and fatigue resistance. There have been many aluminum sailboats built in the French and other parts of the world’s marine industry, and none of them have been retired due to corrosion alone. We have never heard of Garcia’s, Ovni’s or Cigale’s, Alliage’s, Alu Marine’s, Meta’s, and other aluminums sailboats whose life ended due to corrosion. In fact experts remain unable to estimate the final lifetime of aluminum structures in a marine environment, and they consider that an aluminum structure will last forever.
We have seen boats with galvanic corrosion problems due to electrolysis, or stainless steel direct contact with the aluminum. One instance was at the engine exhaust stainless steel pipe which was not properly insulated from the hull. Our boats are built with extra care in keeping all stainless steel parts isolated from the aluminum. Our designs keep stainless steel or non-neutral materials and parts to the very minimum required. Our electrical DC and AC installations are done according to the state of the art and rules of the classifications bureaus, which dictate that no current will ever flow in the structure. That includes full bi-polar wiring with high marine quality H07 RN-F electric wires of extreme insulation resistance, and all precautions such as isolation transformers, accurate and reliable leak testers, and properly placed anode protections. Even at an advanced state of corrosion due to careless isolation or electrical faults, once the problem has been identified, full aluminum repair with proper isolation can be done easily and at very reasonable costs.
Resale value – Aluminum hull boats are extremely durable and they keep their resale value due to the fact that if the hull/structure is known to be good when the boat is brand new, it will not deteriorate with time. We have several instances where owners sold their used boat for the same amount they had paid brand new.
Environment – Aluminum is highly recyclable as it is estimated to require only 5% of the original energy needed to produce the metal. Still, because of its low maintenance and very long durability, and aluminum sailboat is unlikely to be scrapped. The low maintenance of aluminum will actually greatly mitigate the environmental impact, as there is no sandblasting or discharge of volatile organic compounds (VOC).