Boat: GRP VS Aluminum. Which is better and why


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Boat: fiberglass VS aluminum. Here are the merits and demerits

First mistake? Making it a religious war. Both construction techniques obviously have merits and demerits. A very popular approach is to try to compare two materials; in fact, fiberglass is a composite (precisely of fiberglass and resin) that can have a wide variety of different characteristics and, more importantly, can be processed and laminated using very different techniques.

GRP or aluminum: to each his own

Second mistake? Apply absolute values to the two different construction methodologies regardless of the specific boat being discussed. It varies greatly, for example, between small and large vessels, and in turn, within the same size range, much varies depending on the type of use. Example? A 10-meter competition boat will easily be aluminum, a 10-meter cruising or charter boat will be fiberglass.

vtr or aluminum
Baglietto T 52 is a hybrid-powered superyacht with a steel hull and aluminum superstructure

Fiberglass or aluminum: many or few?

Fiberglass is the realm of seriality. It is the obvious choice for producing boats in large numbers. This is because it is based on construction on molds, which can be depreciated over time. So if the starting cost is higher (I have to precisely make the molds) in the course of mass production I am going to recoup it and (if the boat is successful, of course) make a profit.

Importantly, modern production boats are born from a boundless number of molds. It comes to mind only those in the hull and deck, but in fact almost everything (lockers, cabinets, closets, hatches, bathrooms..) is born with this technique. In addition, multiple models often share the same molds. Economy of scale dictates this.

vtr or aluminum
The laying of gel-coat on the mold, the “first stone” in the making of a new vtr boat

In composites, molds command

Designers and project managers working on large construction sites spend much of their time optimizing this interlocking game. Their creativity also manifests itself in this (sometimes especially in this): goal to contain costs.

GRP Thanks to machining on molds (especially the latest ones made in 3D or with hyper-technology milling cutters) allows great creativity in inventing shapes. For aluminum, the design limitations are much more sensitive from this point of view (at least as long as we are talking about boats of a certain size…).

GRP and environmental impact

GRP requires construction techniques with a much heavier environmental impact than aluminum. On the one hand during production due to the production of gases harmful to the health of operators during processing (although the now widespread infusion technique has definitely improved the situation), and on the other hand during disposal. Being a composite, it is virtually impossible to dispose of by separating the fiberglass from the resin. Here, too, great strides are being made in research and early serial applications, but we are still in our infancy.

Aluminum = recycling

Aluminum on the other hand is 100 percent recyclable, and in addition, boats made of this material are much easier to “disassemble,” break down, and scrap once they reach the end of their life. The other big advantage is then, since they do not need molds, they are the realm of custom

Creating matter…

Entering a shipyard that builds boats out of this material feels like arriving in magical places, in caves where men deform, and “create” matter. They cut and weld. Not surprisingly, for this reason, large megayachts are made, for decks and superstructures, of this material. Customization is absolute; the owner asks, the shipyard fulfills.

Similarly, even on small boats, crafts and inflatable boats, it allows for absolute customization. Even DIY. Obviously, work hours and thus final costs increase.

Highfield inflatable boats
Highfield is a shipyard that specializes in building high-quality aluminum-hulled Ribs. Haedquarter in Europe, production in China

Aluminum = lightness

Last, but certainly not in terms of importance, we mention another “heavy trump” that aluminum has to play: lightness. That is why racing boats are made of aluminum, and the same, as we said before, is true for the highest parts of mega and giga yachts; likewise are the american bass-boats or in general small fishing boats that need to be easily hauled and launched, and perhaps loaded onto carts or even onto the roofs of cars and vans.

All this, as is evident, in a nutshell and from the perspective of construction techniques. From the point of view of the end user, the yachtsman, the issue is completely different and will be the subject of another BAM article, Motor Boats.


Why aluminum Why the GRP
Lightness Low cost (in mass production)
Recyclability Modelability
Robustness Robustness
Resilience There are different techniques and different materials as needed
Low cost (in small series or one-offs) Lower costs in operator training



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